DOCSLIB.ORG

Dry Process Fluorination of Uranium Dioxide Using Ammonium Bifluoride LIBRARIES SCIENCE

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Dry Process Fluorination of Uranium Dioxide Using Ammonium Bifluoride LIBRARIES SCIENCE Dry Process Fluorination of Uranium Dioxide Using Ammonium Bifluoride by Charles Burnett Yeamans B.S., Chemical Engineering and Nuclear Engineering (2001) University of California, Berkeley Submitted to the Department of Nuclear Engineering as One Element of Fulfillment of the Requirements for the Degree of Master of Science in Nuclear Engineering at the MASSACHUSETTS INSTIl UTE Massachusetts Institute of Technology OF TECHNOLOGY 0 5 200 September 2003 DEC 3 LIBRARIES © 2003 Massachusetts Institute of Technology all rights reserved Signature of Author: W Department of Nuclear Engineering June 30, 2003 Certified by: Kenneth R. Czerwinski Associate Professor of Nuclear Engineering Thesis Supervisor Certified by: . John R. FitzPatrick Techn1 '' ' ;al Laboratory Fhesis Reader Accepted by: Jeffery Coderre Chair, Department Committee on Graduate Studies SCIENCE THIS PAGE INTENTIONALLY LEFT BLANK Dry Process Fluorination of Uranium Oxides using Ammonium Bifluoride by Charles Burnett Yeamans Submitted to the Department of Nuclear Engineering as Partial Fulfillment of the Requirements for the Degree of Master of Science in Nuclear Engineering ABSTRACT An experimental study was conducted to determine the practicality of various unit operations for fluorination of uranium dioxide. The objective was to prepare ammonium uranium fluoride double salts from uranium dioxide and ammonium bifluoride, then decompose these salts to uranium tetrafluoride through heating to temperatures near 425 'C in either a fluidized bed or a stirred bed. Fluorination in the stirred bed was attempted without pretreatment of the reagents. For the fluidized bed experiments, reagents were ball-milled prior to being heated in the bed. Experiments were conducted in either argon or 4% hydrogen in argon. The ball mill appeared to be an effective technique for fluorinating uranium dioxide with ammonium bifluoride. Samples changed color from brown to bright green, and no oxides could be detected in the x-ray diffraction pattern of the product. It was found that stainless steel is a suitable material of construction for reaction vessels, whereas mild steel parts corroded quickly. Only a small degree of fluidization provided adequate mixing in fluidized beds, but a paddle mixing the stirred beds left an unmixed region around the bed perimeter. Results from the stirred beds showed the initial fluorination reaction completed only when the reagents were heated to 110 'C for at least three hours under argon. Decomposition took place under argon with a temperature ramp up to 425 'C. The product UF 4 contained less than 1%oxide as an impurity, and the decomposition appeared to be complete. Fluidized beds were run with both argon and 4% hydrogen in argon as carrier gases. Experiments with 4% hydrogen in argon produced uranium tetrafluoride, with ammonium uranium pentafluoride and uranium dioxide as impurties. Experiments in argon produced uranium tetrafluoride, with uranyl difluoride, ammonium diuranyl pentafluoride and triuranium octoxide as impurities. Minimum temperatures and times needed to decompose the double salt in the fluidized beds were 200 minutes at 115 'C, a 500-minute ramp to 425 *C, and 200 minutes at 425 'C. The intermediate double salt produced at 110 'C appeared to be triammonium uranium septafluoride. Thesis Supervisor: Kenneth R. Czerwinski Associate Professor, Department of Nuclear Engineering Thesis Reader: John R. FitzPatrick Technical Staff Member, Los Alamos National Laboratory THIS PAGE INTENTIONALLY LEFT BLANK Dedicated to Steve Yeamans, Bill Burnett, and David Pierce In Los Alamos: Michael Martinez was absolutely indispensable, and without him I'm sure I never would have completed this project. Bobby Gonzalez, Gene Zimmerman, and Toby Romero got me the stuff to keep my equipment running, whether it had to be bought, made, borrowed, or "borrowed." Lorraine Vigil shoveled through the snowstorm of paperwork, and Louis Rivera kept me company, as was required by security regulations. Brad Shake made sure I had the tools and safety glasses I needed. Amy Canstefneda did most of the preliminary work without being able to take much credit. The library staff humored my requests for obscure articles from long-defunct journals and found most of them among dusty storage room shelves. In Cambridge: Karen Noyes, Gini Curran, and Jon Plaue know all the secret doors, cabinets, handshakes, signs, rooms, and forms it takes to navigate through MIT, as well as answering all of my stupid questions about where to find things. Mathieu Salanne translated all of my French and Belgian references, and for that I owe him a hamburger and French fries (which he informs me are actually Belgian). In addition to that, his work on the project I was supposed to be doing was nothing short of phenomenal, thus diverting enough attention from me to work on this one without harassment. Andy Gallant suggested enough changes to my experimental equipment such that it would actually be possible to construct, and then streamlined it through the machine shop ahead of all the undergraduate thesis projects. The University of California, Berkeley Department of Nuclear Engineering will allow me to pursue my dream of cleaning up other people's radioactive garbage now that MIT has given up on it. Per Peterson talked me into being a nuclear engineer because it's important. My advisor Ken Czerwinski, a.k.a. Flipper and a member of the LFHCfS, continues to be the grooviest cat ever to grace the sciences. He has given me the freedom to do this project for no better reason than I wanted to pursue it. As always, he sends his love. John FitzPatrick came up with this whole idea, and then let me take it with me. I'd like to thank any deities and/or godlike entities who may have assisted me in this project, although no such help was solicited nor knowingly accepted. Apologies: Susan KcKinney, I'm sorry I argued so much that you had to kick me out of high school chemistry. All molecular motion does cease at 0 *C and I was wrong to insist that it didn't. To the sociology department at Berkeley, sociology is not a "pseudoscience," nor is its research methodology "systematically and pathologically unscientific." I was wrong to say those things, among others, and I'm sorry I made your Sociology 3 professor cry. Louie Cernicek, sorry about your back yard, man. Next time I'll do a more thorough job of gluing the fins on the rocket. Mrs. Fox, I never should have flipped you off. That was very rude of me, even though you deserved it. Mrs. Dorin, it was petty of me to repeatedly suggest that it was both trivial and pointless to complete ream after ream of long-division practice sheets. I can't imagine where my life would be without long division... oh the long division I have done since then. You were right to give me even more reams of long-division practice sheets to teach me how to be a better human being. Oh, and I'm sorry I flipped you off, even though you deserved it. Principal Paluzcek, elementary school was not "a big fat waste of my time" and you and your teachers were not "glorified babysitters" and I'm sorry about attempting to tamper with your brakes. In addition, I apologize for making you spend so much time talking to me about my behavior. I can't help but think that if I had just been quiet, paid attention, walked on the sidewalk, followed the rules, and done as I was told I could have done something with my life... maybe even gone to college. Oh, and I'm sorry I flipped you off, even though you deserved it. Contents page Abstract 3 Acknowledgements Contents List of Figures List of Tables Chapter 1: Introduction 11 1.1 Motivation 11 1.2 Experimental Overview 12 Chapter 2: Background 13 2.1 Physical and Chemical Properties of Uranium Compounds 13 2.1.1 Oxides 13 2.1.2 Fluorides and Ammonium Fluorides 14 2.2 Chemical Behavior of the Ammonium-Uranium-Fluoride System 14 2.3 Common Methods for Preparation of Uranium Tetrafluoride 17 2.4 Fluidized Bed Technology in Uranium Processing 17 2.5 Fluidized Bed Behavior 17 Chapter 3: Experimental Equipment and Procedure 21 3.1 General Considerations 21 3.2 Experimental Descriptions 21 3.2.1 Ambient Temperature Fluorination 21 3.2.1.1 Unagitated Reactants 21 3.2.1.2 Manually Agitated Reactants 22 3.2.1.3 Mechanically Agitated Reactants 22 3.2.2 Stirred Bed 22 3.2.3 Fluidized Beds 24 3.2.3.1 Small Glass Column 24 3.2.3.2 Large Glass Column 24 3.2.3.3 Full-Scale Stainless Steel Column 26 3.2.3.3.1 Experimental Apparatus 26 3.2.3.3.2 Temperature Monitoring and Control 27 3.2.3.3.3 Temperature Cycles 27 3.2.3.3.4 Feedstock 28 Chapter 4: Analytical Methods 4.1 General Comments 4.2 Uranium Mass Fraction 4.3 Soluble Uranyl Fluoride Content 4.4 Oxygen Content 4.5 Nitrogen Content 4.6 Thermogravametric Analysis 4.7 X-Ray Diffraction page Chapter 5: Results and Discussion 33 5.1 Fluorination of Uranium Dioxide 33 5.1.1 Unagitated Reactants 33 5.1.2 Mechanically Mixed Reactants 33 5.1.2.1 Stirred Bed 33 5.1.2.2 Ball Mill 34 5.1.2.3 Small Fluidized Bed 37 5.2 Decomposition of the Double Salt 39 5.2.1 Stirred Bed Reactor 39 5.2.2 Fluidized Bed 40 5.2.2.1 Intermediate Product 40 5.2.2.2 Final Product: UF4 43 5.3 Materials Durability and Structural Integrity 50 5.4 Bed Fluidization 50 Chapter 6: Conclusion 6.1 Effectiveness of Ball Mill Technique for Fluorination 6.2 Effects of Plateau Temperatures 6.2.1 Lower Plateau Temperature 6.2.2 Upper Plateau Temperature 6.3 Effects of Hold Times 6.3.1 Lower Hold Time 6.3.2 Upper Hold Time 6.4 Effects of carrier gas 6.5 Suitability of Construction
Load more

Recommended publications
  • Extensive Interest in Nuclear Fuel Cycle Technologies
    Institute for Science and International Security ISIS REPORT March 19, 2012 Department 70 and the Physics Research Center: Extensive Interest in Nuclear Fuel Cycle Technologies By David Albright, Paul Brannan, Mark Gorwitz, and Andrew Ortendahl On February 23, 2012, ISIS released the report, The Physics Research Center and Iran’s Parallel Military Nuclear Program, in which ISIS evaluated a set of 1,600 telexes outlining a set of departments or buying centers of the former Physics Research Center (PHRC). These departments appeared to be purchasing a variety of goods for specific nuclear technologies, including gas centrifuges, uranium conversion, uranium exploration and perhaps mining, and heavy water production. Figure 1 is a list of the purposes of these departments. The telexes are evaluated in more depth in the February 23, 2012 ISIS report and support that, contrary to Iran’s statements to the International Atomic Energy Agency (IAEA), the PHRC ran a parallel military nuclear program in the 1990s. In the telexes, ISIS identified a department called Department 70 that is linked to the PHRC. This department tried to procure or obtained technical publications and reports from a document center, relevant know-how from suppliers, catalogues from suppliers about particular goods, and a mini- computer from the Digital Equipment Corporation. Department 70 appears to have had personnel highly knowledgeable about the existing literature on a variety of fuel cycle technologies, particularly gas centrifuges. Orders to a British document center reveal many technical publications about gas centrifuges, atomic laser isotope enrichment, the production of uranium compounds including uranium tetrafluoride and uranium hexafluoride (and precursors such as hydrofluoric acid), nuclear grade graphite, and the production of heavy water.
    [Show full text]
  • A Guide to Export Controls
    Foreign Affairs, Trade and Affaires étrangères, Commerce et Development Canada Développment Canada A Guide To CANADA’S EXPORT CONTROLS December 2012 Introduction The issuance of export permits is administered by the Export Controls Division (TIE) of Foreign Affairs, Trade and Development Canada (DFATD). TIE provides assistance to exporters in determining if export permits are required. It also publishes brochures and Notices to Exporters that are freely available on request and on our website www.exportcontrols.gc.ca. How to contact us: Export Controls Division (TIE) Foreign Affairs, Trade and Development Canada 111 Sussex Drive Ottawa, Ontario K1A 0G2 Telephone: (613) 996-2387 Facsimile: (613) 996-9933 Email: [email protected] For information on how to apply for an export permit and additional information on export controls please refer to our website. To enquire on the status of an export permit application: Recognized EXCOL users can check the status of an export permit application on-line. Non-recognized users can call (613) 996-2387 or email [email protected] and quote your export permit application identification (ref ID) number. Export Controls Division website: www.exportcontrols.gc.ca This Guide, at time of publication, encompasses the list of items enumerated on the Export Control List (ECL) that are controlled for export in accordance with Canadian foreign policy, including Canada’s participation in multilateral export control regimes and bilateral agreements. Unless otherwise specified, the export controls contained in this Guide apply to all destinations except the United States. Canada’s Export Control List can be found at the Department of Justice website at http://canada.justice.gc.ca/.
    [Show full text]
  • Key Official US and IAEA Statements About Iran's Nuclear Programs
    Key Official US and IAEA Statements About Iran’s Nuclear Programs Anthony H. Cordesman There is a great deal of speculation about Iran’s nuclear programs that do not list sources or reflect the views of the US intelligence community. It is worth examining what top US intelligence official have said during the last few years, and the details of the IAEA report published in November 2011 – one that clearly reflected official inputs from the US and a number of European intelligence services. U.S. Official Statements on the Iranian Nuclear and Missile Threat The annual unclassified reports to Congress by the Office of the Director of National Intelligence are a key source of US official view. Although the 2010 report by James R. Clapper has already been partly overtaken by the pace of Iran’s rapidly developing program, it still represents the most detailed unclassified estimate of Iran’s capabilities by a senior US official:1 Nuclear We continue to assess Iran is keeping open the option to develop nuclear weapons though we do not know whether Tehran eventually will decide to produce nuclear weapons. Iran continues to develop a range of capabilities that could be applied to producing nuclear weapons, if a decision is made to do so. During the reporting period, Iran continued to expand its nuclear infrastructure and continued uranium enrichment and activities related to its heavy water research reactor, despite multiple United Nations Security Council Resolutions since late 2006 calling for the suspension of those activities. Although Iran made progress in expanding its nuclear infrastructure during 2001, some obstacles slowed progress during this period.
    [Show full text]
  • The Role of Pe, Ph, and Carbonate on the Solubility of UO2 and Uraninite Under Nominally Reducing Conditions
    Geochimica et Cosmochimica Acta, Vol. 62, No. 13, pp. 2223–2231, 1998 Copyright © 1998 Elsevier Science Ltd Pergamon Printed in the USA. All rights reserved 0016-7037/98 $19.00 1 .00 PII S0016-7037(98)00140-9 The role of pe, pH, and carbonate on the solubility of UO2 and uraninite under nominally reducing conditions 1 1 1 1 2 2 3, IGNASI CASAS, JOAN DE PABLO, JAVIER GIMENEZ´ , M. ELENA TORRERO, JORDI BRUNO, ESTHER CERA, ROBERT J. FINCH, * and 3,† RODNEY C. EWING 1Department of Chemical Engineering, Polytechnic University of Catalunya, Barcelona 08028, Spain 2QuantiSci SL, Parc Tecnolo`gic del Valle`s, Cerdanyola 08290, Spain 3Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, New Mexico 87131, USA (Received August 14, 1997; accepted in revised form March 26, 1998) Abstract—Experimental data obtained from uranium dioxide solubility studies as a function of pH and under nominally reducing conditions in a 0.008 mol dm23 perchlorate medium and in a 1 mol dm23 chloride solution are presented. The solubility of extensively characterized uraninite samples from Cigar Lake (Canada), Jachymov (Czech Republic), and Oklo (Gabon) was determined in a solution matching the composition of a groundwater associated with granitic terrain. The redox potential of the test solution was monitored throughout the experimental period. The results obtained were modeled using aqueous formation constants compiled by the NEA, using stability constants corrected to appropriate ionic strengths. The solubility curves have been adjusted by calculating the 1 N value of Ks4 (UO2(s) 2H2O U(OH)4(aq)) that gave the best fit with the experimental data.
    [Show full text]
  • Depleted Uranium Hexafluoride: Waste Or Resource?
    UCRGJC-120397 PREPRINT Depleted Uranium Hexafluoride: Waste or Resource? N. Schwertz J. Zoller R Rosen S. Patton C. Bradley A. Murray This paper was prepared for submittal to the Global ‘95 International Conference on Evaluation of Emerging Nuclear Fuel Cycle Systems Versailles, France September 11-14,1995 July 1995 This isa preprint of apaper intended for publication in a jaurnal orproceedings. Since changes may be made before publication, this preprint is made available with the understanding that it will not be cited or reproduced without the permiasion of the anthor. DISCLAIMER This document was prepared as an account of work sponsored by an agency of the United Stat= Government. Neither theunited States Governmentmor theuniversity of California nor any oftheir employees, makes any warranty, express or implied, or assumesanylegalliabilityorrespomibility forthe accuracy,completeness,orusefuin~ of any information, apparatus, pduct, or process disdosed, or represents that its use wouldnotinfringe privatelyowned rights. Referencehemin to anyspe&c commercial prodocis, proms, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constituteor imply its endorsement, reconunendation, or favoring by the United States Government or the University of California. The views and opinions of authors expressed herein do not necessady state or reflect those of the United States Government or the University of California, and shall not be used for adveltising or product endorsement purposes. DISCLAIMER Portions of this document may be illegible in electronic image products. Images are produced from the best available original document . DEPLETED URANIUM HEXAFLUORIDE: WASTE OR RESOURCE? N. Schwertz, J. Zoller, R. Rosen, S. Patton LAWRENCE LIVERMORE NATIONAL LABORATORY P.
    [Show full text]
  • Measurement of Uranium Dioxide Thermophysical Properties by the Laser Flash Method
    2009 International Nuclear Atlantic Conference - INAC 2009 Rio de Janeiro,RJ, Brazil, September27 to October 2, 2009 ASSOCIAÇÃO BRASILEIRA DE ENERGIA NUCLEAR - ABEN ISBN: 978-85-99141-03-8 MEASUREMENT OF URANIUM DIOXIDE THERMOPHYSICAL PROPERTIES BY THE LASER FLASH METHOD Pablo Andrade Grossi 1, Ricardo Alberto Neto Ferreira 2, Denise das Mercês Camarano 3, Roberto Márcio de Andrade 4 1,2,3 Centro de Desenvolvimento da Tecnologia Nuclear-CDTN Comissão Nacional de Energia Nuclear-CNEN Av. Presidente Antônio Carlos 6627 Cidade Universitária-Pampulha-Caixa Postal 941 CEP: 31.161-970 Belo Horizonte, MG 1 [email protected] 2 [email protected] 3 [email protected] 4 Departamento de Engenharia Mecânica Escola de Engenharia da Universidade Federal de Minas Gerais Av. Presidente Antônio Carlos 6627-Cidade Universitária-Pampulha CEP: 31.270-901 - Belo Horizonte – MG - Brasil 4 [email protected] ABSTRACT The evaluation of the thermophysical properties of uranium dioxide (UO 2), including a reliable uncertainty assessment, are required by the nuclear reactor design. These important informations are used by thermohydraulic codes to define operational aspects and to assure the safety, when analyzing various potential situations of accident. The Laser Flash Method had become the most popular method to measure the thermophysical properties of materials. Despite its several advantages, some experimental obstacles have been found due to the difficulty to obtain experimentally the ideals initial and boundary conditions required by the original method. An experimental apparatus and a methodology for estimating uncertainties of thermal diffusivity, thermal conductivity and specific heat measurements based on the Laser Flash Method are presented. A stochastic thermal diffusion modeling has been developed and validated by Standard Samples.
    [Show full text]
  • Depleted Uranium Technical Brief
    Disclaimer - For assistance accessing this document or additional information,please contact [email protected]. Depleted Uranium Technical Brief United States Office of Air and Radiation EPA-402-R-06-011 Environmental Protection Agency Washington, DC 20460 December 2006 Depleted Uranium Technical Brief EPA 402-R-06-011 December 2006 Project Officer Brian Littleton U.S. Environmental Protection Agency Office of Radiation and Indoor Air Radiation Protection Division ii iii FOREWARD The Depleted Uranium Technical Brief is designed to convey available information and knowledge about depleted uranium to EPA Remedial Project Managers, On-Scene Coordinators, contractors, and other Agency managers involved with the remediation of sites contaminated with this material. It addresses relative questions regarding the chemical and radiological health concerns involved with depleted uranium in the environment. This technical brief was developed to address the common misconception that depleted uranium represents only a radiological health hazard. It provides accepted data and references to additional sources for both the radiological and chemical characteristics, health risk as well as references for both the monitoring and measurement and applicable treatment techniques for depleted uranium. Please Note: This document has been changed from the original publication dated December 2006. This version corrects references in Appendix 1 that improperly identified the content of Appendix 3 and Appendix 4. The document also clarifies the content of Appendix 4. iv Acknowledgments This technical bulletin is based, in part, on an engineering bulletin that was prepared by the U.S. Environmental Protection Agency, Office of Radiation and Indoor Air (ORIA), with the assistance of Trinity Engineering Associates, Inc.
    [Show full text]
  • CA004600 SDS.Pdf
    Safety Data Sheet SECTION 1: Identification 1.1. Product Identifier Trade Name or Designation: Ammonium Bifluoride, 15.5 g/L, Aqueous Product Number: A-0046 Other Identifying Product Numbers: A-0046-4L 1.2. Recommended Use and Restrictions on Use General Laboratory Reagent 1.3. Details of the Supplier of the Safety Data Sheet Company: Reagents Inc. Address: 4746 Sweden Road Charlotte, NC 28224 USA Telephone: 800-732-8484 1.4. Emergency Telephone Number (24 hr) CHEMTREC (USA) 800-424-9300 CHEMTREC (International) 1+ 703-527-3887 SECTION 2: Hazard(s) Identification 2.1. Classification of the Substance or Mixture (in accordance with OSHA HCS 29 CFR 1910.1200) For the full text of the Hazard and Precautionary Statements listed below, see Section 16. Hazard Hazard Class Category Statement Precautionary Statements Skin Corrosion / Irritation Category 1 H314 P260, P264, P280, P301+P330+P331, P303+P361+P353, P363, P304+P340, P310, P321, P305+P351+P338, P405, P501 Eye Damage / Irritation Category 1 H318 P280, P305+P351+P338, P310 Specific Target Organs/Systemic Toxicity Following Single Category 1 H370 P260, P264, P270, P307+P311, P321, P405, Exposure P501 Specific Target Organs/Systemic Toxicity Following Repeated Category 2 H373 P260, P314, P501 Exposure Corrosive to Metals Category 1 H290 P234, P390, P406 Product Number: A-0046 Page 1 of 10 Safety Data Sheet 2.2. GHS Label Elements Pictograms: Signal Word: Danger Hazard Statements: Hazard Number Hazard Statement H290 May be corrosive to metals. H314 Causes severe skin burns and eye damage. H318 Causes serious eye damage. H370 Causes damage to organs. H373 May cause damage to organs through prolonged or repeated exposure.
    [Show full text]
  • Ammonium Bifluoride CAS No
    Product Safety Summary Ammonium Bifluoride CAS No. 1341-49-7 This Product Safety Summary is intended to provide a general overview of the chemical substance. The information on the summary is basic information and is not intended to provide emergency response information, medical information or treatment information. The summary should not be used to provide in-depth safety and health information. In-depth safety and health information can be found in the Safety Data Sheet (SDS) for the chemical substance. Names • Ammonium bifluoride (ABF) • Ammonium difluoride • Ammonium acid fluoride • Ammonium hydrogen difluoride • Ammonium fluoride compound with hydrogen fluoride (1:1) Product Overview Solvay Fluorides, LLC does not sell ammonium bifluoride directly to consumers. Ammonium bifluoride is used in industrial applications and in other processes where workplace exposures can occur. Ammonium bifluoride (ABF) is used for cleaning and etching of metals before they are further processed. It is used as an oil well acidifier and in the etching of glass or cleaning of brick and ceramics. It may also be used for pH adjustment in industrial textile processing or laundries. ABF is available as a solid or liquid solution (in water). Ammonium bifluoride is a corrosive chemical and contact can severely irritate and burn the skin and eyes causing possible permanent eye damage. Breathing ammonium bifluoride can severely irritate and burn the nose, throat, and lungs, causing nosebleeds, cough, wheezing and shortness of breath. On contact with water or moist skin, ABF can release hydrofluoric acid, a very dangerous acid. Inhalation or ingestion of large amounts of ammonium bifluoride can cause nausea, vomiting and loss of appetite.
    [Show full text]
  • High-Density Concrete with Ceramic Aggregate Based on Depleted Uranium Dioxide
    HIGH-DENSITY CONCRETE WITH CERAMIC AGGREGATE BASED ON DEPLETED URANIUM DIOXIDE S.G. Ermichev, V.I. Shapovalov, N.V.Sviridov (RFNC-VNIIEF, Sarov, Russia) V.K. Orlov, V.M. Sergeev, A. G. Semyenov, A.M. Visik, A.A. Maslov, A. V. Demin, D.D. Petrov, V.V. Noskov, V. I. Sorokin, O. I. Uferov (VNIINM, Moscow, Russia) L. Dole (ORNL, Oak Ridge, USA) Abstract - Russia is researching the production and testing of concretes with ceramic aggregate based on depleted uranium dioxide (UO2). These DU concretes are to be used as structural and radiation-shielded material for casks for A-plant spent nuclear fuel transportation and storage. This paper presents the results of studies aimed at selection of ceramics and concrete composition, justification of their production technology, investigation of mechanical properties, and chemical stability. This Project is being carried out at the A.A. Bochvar All-Russian Scientific-Research Institute of inorganic materials (VNIINM, Russia) and Russian Federal Nuclear Center – All-Russia Scientific Research Institute of Experimental Physics (RFNC-VNIIEF, Russia). This Project #2691 is financed by the International Science and Technology Center (ISTC) under collaboration of the Oak- Ridge National Laboratory (USA) I. INTRODUCTION The current practice of ensuring the required gamma conduction, thermo-, radiation and corrosion resistance, shielding and strength of metal-concrete casks is based on service life and water resistance. concrete density. For this purpose high-density rocks Specific characteristics of UO2’s chemical activity (magnetite, iron glance, barium sulfate, etc.) as well as because of its small size of particles and thus great specific scrap, scale, broken metal chips and others are introduced surface area prevent the use of traditional methods of UO2 into concrete as coarse aggregates.
    [Show full text]
  • Uranium Aerosols at a Nuclear Fuel Fabrication Plant: Characterization Using Scanning Electron Microscopy and Energy Dispersive X-Ray Spectroscopy
    Spectrochimica Acta Part B 131 (2017) 130–137 Contents lists available at ScienceDirect Spectrochimica Acta Part B journal homepage: www.elsevier.com/locate/sab Uranium aerosols at a nuclear fuel fabrication plant: Characterization using scanning electron microscopy and energy dispersive X-ray spectroscopy E. Hansson a,b,⁎, H.B.L. Pettersson a, C. Fortin c, M. Eriksson a,d a Department of Medical and Health Sciences, Linköping University, 58185 Linköping, Sweden b Westinghouse Electric Sweden AB, Bränslegatan 1, 72136 Västerås, Sweden c Carl Zeiss SAS, 100 route de Versailles, 78160 Marly-le-Roi, France d Swedish Radiation Safety Authority, 17116 Stockholm, Sweden article info abstract Article history: Detailed aerosol knowledge is essential in numerous applications, including risk assessment in nuclear industry. Received 31 March 2016 Cascade impactor sampling of uranium aerosols in the breathing zone of nuclear operators was carried out at a Received in revised form 28 February 2017 nuclear fuel fabrication plant. Collected aerosols were evaluated using scanning electron microscopy and energy Accepted 3 March 2017 dispersive X-ray spectroscopy. Imaging revealed remarkable variations in aerosol morphology at the different Available online 6 March 2017 workshops, and a presence of very large particles (up to≅100 × 50 μm2) in the operator breathing zone. Charac- teristic X-ray analysis showed varying uranium weight percentages of aerosols and, frequently, traces of nitrogen, Keywords: fl Uranium uorine and iron. The analysis method, in combination with cascade impactor sampling, can be a powerful tool Aerosol for characterization of aerosols. The uranium aerosol source term for risk assessment in nuclear fuel fabrication Impactor appears to be highly complex.
    [Show full text]
  • Dissolution of Uranium Dioxide in Nitric Acid Media: What Do We Know?
    EPJ Nuclear Sci. Technol. 3, 13 (2017) Nuclear © Sciences P. Marc et al., published by EDP Sciences, 2017 & Technologies DOI: 10.1051/epjn/2017005 Available online at: http://www.epj-n.org REGULAR ARTICLE Dissolution of uranium dioxide in nitric acid media: what do we know? Philippe Marc1, Alastair Magnaldo1,*, Aimé Vaudano1, Thibaud Delahaye2, and Éric Schaer3 1 CEA, Nuclear Energy Division, Research Department of Mining and Fuel Recycling Processes, Service of Dissolution and Separation Processes, Laboratory of Dissolution Studies, 30207 Bagnols-sur-Cèze, France 2 CEA, Nuclear Energy Division, Research Department of Mining and Fuel Recycling Processes, Service of Actinides Materials Fabrication, Laboratory of Actinide Conversion Processes, 30207 Bagnols-sur-Cèze, France 3 Laboratoire Réactions et Génie des Procédés, UMR CNRS 7274, University of Lorraine, 54001 Nancy, France Received: 16 March 2016 / Received in final form: 15 November 2016 / Accepted: 14 February 2017 Abstract. This article draws a state of knowledge of the dissolution of uranium dioxide in nitric acid media. The chemistry of the reaction is first investigated, and two reactions appear as most suitable to describe the mechanism, leading to the formation of monoxide and dioxide nitrogen as reaction by-products, while the oxidation mechanism is shown to happen before solubilization. The solid aspect of the reaction is also investigated: manufacturing conditions have an impact on dissolution kinetics, and the non-uniform attack at the surface of the solid results in the appearing of pits and cracks. Last, the existence of an autocatalytic mechanism is questionned. The second part of this article presents a compilation of the impacts of several physico-chemical parameters on the dissolution rates.
    [Show full text]