DOCSLIB.ORG

United States Patent Ti9] [Ii] 3,806,579 Carles Et Al

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
United States Patent Ti9] [Ii] 3,806,579 Carles Et Al United States Patent ti9] [ii] 3,806,579 Carles et al. [45] Apr. 23, 1974 [54] METHOD OF PURIFICATION OF URANIUM 3,425,812 2/1969 Cousin et al 23/352 HEXAFLUORIDE 3,359,078 12/1967 Alter et al 23/326 3,340,019 9/1967 Pierini et al 23/326 [75] Inventors: Maurice Carles; Jacky Fra, both of Pierrelatte, France Primary Examiner—Carl D. Quarforth [73] Assignee: Commissariat A L'Energie Assistant Examiner—F. M. Gittes Atomique, Paris, France Attorney, Agent, or Firm—Cameron, Kerkam & Sutton [22] Filed: Mar. 22, 1971 [21] Appl. No.: 126,682 [57] ABSTRACT This invention relates to a method of purification of [30] Foreign Application Priority Data uranium hexafluoride contaminated with impurities Apr. 8, 1970 France 70.12685 such as molybdenum hexafluoride and tungsten hexa- fluoride. [52] U.S. CI 423/19, 423/8, 423/258 The contaminated uranium hexafluoride is distilled [51] Int. CI COlg 43/06 from the liquid phase in the presence of chlorine [58] Field of Search 23/326, 339, 352; 423/19, trifluoride which forms an azeotrope with the 423/258, 8 impurities to be removed from the uranium hexafluoride, said impurities are withdrawn from the [56] References Cited top of the column and the purified uranium hexafluoride is collected at the bottom of the column. UNITED STATES PATENTS 2,830,873 4/1958 Katz et al ....23/326 1 Claim, 4 Drawing Figures PATENTED APR 2 3 197^ 1806,579 r°c 0 12% 0 37,5% %MoFe FIG. 1 FIG. 2 /r 4- 6 5 4 3 2 I FIG. 3 FIG. 4 R 3,806,579 1 2 METHOD OF PURIFICATION OF URANIUM nium diuranate by bubbling of uranium hexafluoride HEXAFLUORIDE through ammonia, dissolving the ammonium diuranate which is formed with nitric acid, extraction of the ura- This invention relates to a method of purification of nyl nitrate by tributylphosphate whilst the impurities uranium in the form of uranium hexafluoride which 5 remain in the aqueous phase, stripping of the uranium contains impurities such as molybdenum and tungsten. with a nitric acid solution, action of ammonia on the uranyl nitrate so as to yield ammonium diuranate, cal- Uranium hexafluoride is prepared by the action of cination of the ammonium diuranate in order to form fluorine on uranium tetrafluoride, this compound being UOs, reduction of U03 to U02 by hydrogen, conversion in turn obtained as a result of the action of anhydrous 10 of UOz into UF4 by anhydrous hydrofluoric acid and hydrofluoric acid on uranium dioxide. The product conversion of UF4 into UFS by fluorine. This process thus obtained contains impurities (MoF6, WF6, etc.) involves a large number of stages and calls for substan- which have to be eliminated especially for subsequent tial quantities of pure reagents, use in enrichment plants. The method of purification of uranium hexafluoride The methods of purification of uranium hexafluoride 15 in accordance with the invention essentially consists in involve either distillation or solvent extraction. distilling uranium hexafluoride in the presence of chlo- The first method of purification consists in direct dis- rine trifluoride so as to form an azeotropic mixture with tillation of the gaseous mixture of uranium hexafluo- the impurities which are to be removed from the ura- ride and molybdenum hexafluoride or of the mixture of nium hexafluoride, said impurities being discharged at uranium hexafluoride and tungsten hexafluoride. 20 the top of the column and the purified uranium hexa- Uranium hexafluoride is withdrawn in the pure state fluoride being collected at the bottom of the column, at the bottom of the column. Molybdenum hexafluo- ride and tungsten hexafluoride pass out at the top of the The method is applicable to the removal of any impu- column in the form of a mixture which is rich in ura- rity contained in uranium hexafluoride which forms an nium hexafluoride (approximately 95 percent). 25 azeotropic mixture with chlorine trifluoride provided The second method consists in converting uranium that both miscibility and chemical compatibility exist, hexafluoride into uranyl nitrate and then in extracting the uranium by tributylphosphate. The impurities re- The mixture of uranium hexafluoride and chlorine mains in the aqueous phase. trifluoride is wholly miscible over the entire concentra- Taking into account the low relative volatility of mo- 30 tion range provided that the total pressure remains lybdenum hexafluoride and tungsten hexafluoride with higher than approximately 2,500 mb. Below this value, respect to uranium hexafluoride, a column having a the liquid-vapor equilibrium region encounters a zone large number of plates must be employed for the distil- in which two phases are present, one phase being a lation process in order to permit the separation of Ura- chlorine trifluoride solution which is saturated with nium hexafluoride from its impurities. uranium hexafluoride and the other phase being ura- Two types of separation are possible: nium hexafluoride crystals, with the result that the dis- either it is sought to obtain 100 percent molybdenum tillation process cannot proceed further, hexafluoride of tungsten hexafluoride at the top of The phase equilibrium diagram of the molybdenum the column and 100 percent Uranium hexafluoride hexafluoride-chlorine trifluoride mixture is shown in at the bottom of the column, 40 FIG. 1. The diagram demonstrates the existence of an or it is desired to obtain uranium hexafluoride in the azeotrope which, at a pressure of 3,450 mb, contains pure state at the bottom of the column while limit- 12 percent molybdenum hexafluoride (boiling point: ing the quantity obtained at the top of the column 44.2°C). to a few per cent of molybdenum hexafluoride or FIG. 2 shows the phase equilibrium diagram of the tungsten hexafluoride. 45 tungsten hexafluoride-chlorine trifluoride mixture. In the first case, provision must be made for a distilla- This diagram demonstrates the existence of an azeo- tion column having a large number of plates in order to trope which, at a pressure of 3,450 mb, contains 37.5 carry out the separation process. It is necessary to in- percent tungsten hexafluoride (boiling point: 39.2° C). troduce molybdenum hexafluoride or tungsten hexaflu- 5Q oride in order to set the column at its steady state un- FIG. 3 shows the curve of temperatures along the dis- less the progressive accumulation of impurities at the tillation column in equilibrium with the mixture of UF6 top of the column is first permitted to take place. and C1F3. In the second case, the uranium hexafluoride which FIG. 4 is a diagrammatic view of the distillation col- leaves the top of the column together with the impuri- 55 umn which is employed for carrying out the method, ties must be recovered. Control of the installation is dif- The gas to be purified and the chlorine trifluoride are ficult to achieve since the concentration curve in the introduced at an intermediate point G of the distillation column is known only on the basis of analyses, taking column which contains a packing. However, it is possi- into account the very small temperature difference be- ble to introduce the chlorine trifluoride into the col- tween the top and the bottom of the column (the bot- 6Q umn independently of the gas to be purified, torn of the column is at the boiling temperature of UF6 The column is provided at the base with a reboiler R at the pressure under consideration whilst the top of and an overhead condenser C which returns the UF6 as the column is at a temperature which is close to the reflux. Purified UF6 is withdrawn from the bottom of boiling point of UFS, the gases which leave the top of the column whilst the chlorine trifluoride and the impu- the column being essentially constituted by UFe). 65 rities are withdrawn from the top of the column. The method of purification of uranium hexafluoride The substantial temperature difference between the by chemical separation takes a long time to carry into top and bottom of the column permits easy separation effect. It involves formation of a precipitate of ammo- of impurities from the uranium hexafluoride. As can be 3,529,233 seen from FIG. 3, said difference is of the order of I. These results show the efficiency of the method for 50°C: the temperature at the bottom of the column cor- the separation of molybdenum hexafluoride with a responds to the boiling temperature of UF6 at the pres- small number of plates. sure under consideration (3,450 mb) and the tempera- Since the relative volatility of tungsten hexafluoride ture at the top of the column corresponds to the boiling 5 with respect to chlorine trifluoride is greater than in the temperature of the azeotrope. The concentrations case of molybdenum hexafluoride, it was possible to along the column are perfectly defined, thus avoiding carry out tests more rapidly with tungsten hexafluoride. the need for continuous analytical testing of the purity After introduction of 656 g of tungsten hexafluoride, of the bottom product (pure UF6). the concentrations of this product were: The chlorine trifluoride at the top of the column can 10 at the top of the column (point 1): 10 620 Vpm (point be regenerated either periodically or on a continuous 2): < 0.465 vpm basis. There is therefore found to be a drop from 10 620 Depending on the quantities of chlorine trifluoride vpm to less than 0.465 vpm with 1.683 m of a packing which are consumed, it is possible to recover this latter: of the "heli-pak" type. 15 In order to ensure that the tungsten hexafluoride and either partly, by aeotropic distillation C1F3 — azeo- molybdenum hexafluoride did not have any mutual in- trope ClFs/MoFe or C1F3 azeotrope C1F3/WF6, fluence, (WF and MoF ) were introduced simulta- or totally by trapping molybdenum hexafluoride or 6 e neously.
Load more

Recommended publications
  • 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]
  • 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]
  • Safety Data Sheet Material Name: TUNGSTEN HEXAFLUORIDE SDS ID: MAT24560
    Safety Data Sheet Material Name: TUNGSTEN HEXAFLUORIDE SDS ID: MAT24560 Section 1 - PRODUCT AND COMPANY IDENTIFICATION Material Name TUNGSTEN HEXAFLUORIDE Synonyms MTG MSDS 85; TUNGSTEN FLUORIDE (WF6), (OC-6-11)-; WOLFRAM HEXAFLUORIDE; HEXAFLUOROTUNGSTEN; TUNGSTEN(6+) FLUORIDE; TUNGSTEN HEXAFLUORIDE (WF6); TUNGSTEN VI FLUORIDE; TUNGSTEN FLUORIDE; UN 2196; F6W Chemical Family Fluoride, inorganic, metal Product Use Industrial and Specialty Gas Applications. Restrictions on Use None known. Details of the supplier of the safety data sheet MATHESON TRI-GAS, INC. 3 Mountainview Road Warren, NJ 07059 General Information: 1-800-416-2505 Emergency #: 1-800-424-9300 (CHEMTREC) Outside the US: 703-527-3887 (Call collect) Section 2 - HAZARDS IDENTIFICATION Classification in accordance with paragraph (d) of 29 CFR 1910.1200. Gases Under Pressure - Liquefied gas Acute Toxicity - Inhalation - Gas - Category 2 Skin Corrosion/Irritation - Category 1 Serious Eye Damage/Eye Irritation - Category 1 Specific target organ toxicity - Repeated exposure - Category 1 GHS Label Elements Symbol(s) Signal Word Danger Hazard Statement(s) Contains gas under pressure; may explode if heated. Fatal if inhaled. Causes severe skin burns and eye damage. Causes damage to organs through prolonged or repeated exposure. （bones ） Precautionary Statement(s) Prevention Do not breathe gas. Use only outdoors or in a well-ventilated area. In case of inadequate ventilation wear respiratory protection. ____________________________________________________________ Page 1 of 9 Issue date: 2021-07-07 Revision 7.0 Print date: 2021-07-07 Safety Data Sheet Material Name: TUNGSTEN HEXAFLUORIDE SDS ID: MAT24560 Do not eat, drink or smoke when using this product. Wear protective gloves/protective clothing/eye protection/face protection.
    [Show full text]
  • Tungsten Hexafluoride WF6 Safety Data Sheet SDS P4855
    Tungsten hexafluoride Safety Data Sheet P-4855 This SDS conforms to U.S. Code of Federal Regulations 29 CFR 1910.1200, Hazard Communication. Date of issue: 01/01/1985 Revision date: 10/24/2016 Supersedes: 04/28/2015 SECTION: 1. Product and company identification 1.1. Product identifier Product form : Substance Name : Tungsten hexafluoride CAS No : 7783-82-6 Formula : WF6 Other means of identification : Tungsten hexafluoride 1.2. Relevant identified uses of the substance or mixture and uses advised against Use of the substance/mixture : Industrial use. Use as directed. 1.3. Details of the supplier of the safety data sheet Praxair, Inc. 10 Riverview Drive Danbury, CT 06810-6268 - USA T 1-800-772-9247 (1-800-PRAXAIR) - F 1-716-879-2146 www.praxair.com 1.4. Emergency telephone number Emergency number : Onsite Emergency: 1-800-645-4633 CHEMTREC, 24hr/day 7days/week — Within USA: 1-800-424-9300, Outside USA: 001-703-527-3887 (collect calls accepted, Contract 17729) SECTION 2: Hazard identification 2.1. Classification of the substance or mixture GHS-US classification Liquefied gas H280 Acute Tox. 2 (Inhalation: gas) H330 Skin Corr. 1A H314 Eye Dam. 1 H318 2.2. Label elements GHS-US labeling Hazard pictograms (GHS-US) : GHS04 GHS05 GHS06 Signal word (GHS-US) : DANGER Hazard statements (GHS-US) : H280 - CONTAINS GAS UNDER PRESSURE; MAY EXPLODE IF HEATED H314 - CAUSES SEVERE SKIN BURNS AND EYE DAMAGE H330 - FATAL IF INHALED CGA-HG11 - SYMPTOMS MAY BE DELAYED CGA-HG22 - CORROSIVE TO THE RESPIRATORY TRACT Precautionary statements (GHS-US) : P202
    [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]
  • Certain Data Contained in This Document May Be Difficult to Read in Microfiche Products
    NOTICE CERTAIN DATA CONTAINED IN THIS DOCUMENT MAY BE DIFFICULT TO READ IN MICROFICHE PRODUCTS. dSa./ NREL/MP-451-4778B . UC Category': 270 • DE92 NRHL/MP--451-4778B DE92 04032.1 Safety Analysi%^.eport For the Use of Hal|ardous Production Materials in Photovoltaic Applications at the National Renewable Energy Laboratory Volume II: Appendices •.-ft '4^ oil, R.S, Crandall B»P. Nelson P.D. Moskowitz V.M. Fthenakis *N?S! National Renewable Energy Laboratory 1617 Cole Boulevard Golden, Colorado 80401-3393 A Division of Midwest Research Institute Operated for the U.S. Department of Energv under Contract No. DE-AC02-83CH10093 " July 1992 Hi ^_ oismiuuiiuh or IMUI NOTICE Tnis report was ptepared as an account of work sponsoied by an agency of the United States government Neither the United Slates government nor any agency thereof nor any of their employees, makes any warranty express o< implied or assumes any legal liability Of tesponsibility'or the accuracy completeness or usefulness of any information apparatus product or process disclosed 01 represents that its use would not infringe privately owned, rights Reference herein to any specie commercial product process or service by trade name trademark manufacturer or otherwise ooes not necessarily constitute or imply its endorsement recommendation or favoring by the United Slates government or any agency lhereo> The views and opinions of authors expresseo herein do not necessarily state or reflect those of the United State; government or any agency theieof APPENDICES - TABLE OF CONTENTS A: AffCJtiftflt/RisK
    [Show full text]
  • Gas and Metal Compatibility Guide
    Gas & Metal Compatibility Table Chemical Suggested Choosing a Mott High Purity Gas Filter: Gas Formula Filter Media Choosing the best metal filter is not always a simple Ammonia NH 3 SS/Ni matter, because in addition to easily identified variables Argon Ar SS/Ni Arsenic Pentafluoride AsF 5 SS/Ni (i.e., gas, pressure and flow), there are subjective Arsine AsH 3 SS/Ni(1) considerations. Some gases are compatible with more Boron Trichloride BCI 3 Ni/H than one type of metal which allows you a choice when Boron Trifluoride BF 3 Ni/H Carbon Dioxide CO 2 SS/Ni selecting the right filter for your application. Carbon Monoxide * CO SS * Carbon Tetrachloride CCl 4 SS/Ni The information contained in this table is a guideline for Carbon Tetraflouride CF 4 SS/Ni appropriate filter selection. Consultation with your gas Chlorine Cl 2 SS/Ni/H Diborane B2H6 SS/Ni(1) supplier is recommended to ensure Dichlorosilane SiH 2Cl 2 Ni/H gas compatibility. Because so many Diethyltelluride C4H10 Te SS/Ni Fluorine F2 Ni/H factors can affect the chemical Freon 13 CClF 3 SS/Ni resistance of a given product, you Freon 14 Tetrafluoromethane CF 4 SS/Ni should pretest under your own Freon 23 Trifluoromethane/Fluoro-form CHF 3 SS/Ni Freon 115 Chloropentafluoroethane C2ClF 5 SS/Ni operating conditions. Freon 116 Hexafluoroethane C2F6 SS/Ni As with any Germane GeH 4 SS/Ni Helium He SS/Ni chemical Hydrogen H2 SS/Ni application, Hydrogen Bromide HBr Ni/H Hydrogen Chloride HCl Ni/H safety precautions Hydrogen Fluoride HF Ni/H as noted on MSDS Hydrogen Selenide H2Se SS/Ni sheets should be Hydrogen Sulfide H2S SS/Ni Krypton Kr SS/Ni observed .
    [Show full text]
  • Nuclear Iran a Glossary of Terms
    Nuclear Iran A Glossary of Terms Simon Henderson and Olli Heinonen Policy Focus 121 | May 2013 Update HARVARD Kennedy School A COPUBLICATION WITH BELFER CENTER for Science and International Affairs Map: Nuclear installations in Iran. TURKMENISTAN TABRIZ Bonab Lashkar Abad TEHRAN MASHAD Karaj Marivan Parchin Fordow Arak QOM IRAQ Natanz AFGHANISTAN Isfahan Ardakan Saghand Darkhovin Yazd IRAN KUWAIT SHIRAZ Bushehr PAKISTAN Gchine BANDAR ABBAS BAHRAIN SAUDI ARABIA QATAR © 2012 The Washington Institute for Near East Policy UAE OMAN Map: Nuclear installations in Iran. Nuclear Iran A Glossary of Terms Simon Henderson and Olli Heinonen Policy Focus 121 | May 2013 Update HARVARD Kennedy School A COPUBLICATION WITH BELFER CENTER for Science and International Affairs n n n The authors extend special thanks to Mary Kalbach Horan and her editorial team at The Washington Institute. n n n All rights reserved. Printed in the United States of America. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopy, recording, or any information storage and retrieval system, without permission in writing from the publisher. © 2012, 2013 by The Washington Institute for Near East Policy and the Harvard Kennedy School’s Belfer Center for Science and International Affairs Copublished in 2012 and 2013 in the United States of America by The Washington Institute for Near East Policy, 1828 L Street NW, Suite 1050, Washington, DC 20036; and the Harvard Kennedy School’s Belfer Center for Science and International Affairs, 79 JFK St., Cambridge, MA 02138. Cover photo: Iran’s president Mahmoud Ahmadinejad visits the Natanz nuclear enrichment facility.
    [Show full text]
  • Comprehensive Electronics Solutions Praxair Offers a Full Suite of Electronics Gases, Equipment and Services
    Comprehensive Electronics Solutions Praxair offers a full suite of electronics gases, equipment and services. Applications: Semiconductor From cost effectiveness to supply reliability to product quality – across North LEDs and Photonics America and around the world – Praxair is the gas supply partner with a proven Solar track record of success. Praxair’s experts are uniquely positioned to address the key needs of your operation, helping you remain competitive in today’s Nanotechnology highly complex, global electronics market. Electronics Assembly Product solutions with consistent performance Praxair is your industry-leading electronics solutions provider, backed by the dedicated service and industry know-how of the largest industrial gas company in North America. Whether its cylinder specialty gases for production processes, facility support gases from a microbulk system, or bulk or on-site delivery systems for large quantity demands, electronics manufacturing requires reliable, consistent products and service to get the job done right. Praxair’s complete suite of electronics gases, delivery equipment and services are designed to help you boost productivity and cut costs – crucial to your bottom line. Process gases that support your productivity Praxair’s global track record of supporting electronics producers in semiconductor, LED and electronics assembly markets among others is second to none. Our process gases maximize productivity, reduce process costs and enable new technologies. Count on Praxair for a reliable supply of gases that
    [Show full text]
  • Low Temperature Chemical Vapor Deposition and Method for Depositing a Tungsten Silicide Film with Improved Uniformity and Reduced Fluorine Concentration
    Europaisches Patentamt 19 European Patent Office Office europeen des brevets © Publication number : 0 591 086 A2 12 EUROPEAN PATENT APPLICATION © Application number : 93480132.5 © int. ci.5: H01L 21/3205, C23C 16/44, C23C 16/42, H01L 21/285 @ Date of filing : 10.09.93 The application is published incomplete as filed @ Inventor : Gow, Thomas Richard (Article 93 (2) EPC). The points in the 4 Lyman Drive description at which the omission obviously Williston, VT 05495 (US) occurs have been left blank. Inventor : Lebel, Richard John Box 2255A RD1 © Priority : 30.09.92 US 954783 Sheldon, VT 05483 (US) @ Date of publication of application : @ Representative : Klein, Daniel Jacques Henri 06.04.94 Bulletin 94/14 Compagnie IBM France Departement de Propriete Intellectuelle @ Designated Contracting States : F-06610 La Gaude (FR) DE FR GB © Applicant : International Business Machines Corporation Old Orchard Road Armonk, N.Y. 10504 (US) © Low temperature chemical vapor deposition and method for depositing a tungsten silicide film with improved uniformity and reduced fluorine concentration. © A tungsten silicide (WSix) film is formed by GROWTH RATE ( mg/m i n ) chemical vapor deposition using the reduction of tungsten hexafluoride (WF6) with dichlorosi- O — ro lane (SiH2CI2) referred to as DCS and a reduc- ing agent comprising silane (SiH4), hydrogen, or a mixture thereof. According to the method of the present invention, the WSix film is formed in a CVD reactor operating at a low pressure and at a wafer temperature between about 300 and 550°C. In the preferred embodiment, a thin nucleation layer is deposited before the WSix film.
    [Show full text]
  • Sorption of Np and Tc in Underground Waters by Uranium Oxides
    Sorption of Np and Tc in Underground Waters by Uranium Oxides T.V.Kazakovskaya,a V.I. Shapovalova, N.V. Kushnira , E.V. Zakharovab, S.N.Kalmykovb O.N.Batukb, M.J.Hairec a –Russian Federal Nuclear center –All-Russia Scientific Institute of Experimental Physics; 607190, Sarov, Russia, E-mail: [email protected]; b – Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Moscow, Russia, c – Oak Ridge National Laboratory, Oak Ridge, Tennessee. Abstract –The production of nuclear fuels results in the accumulation of large quantities of depleted uranium (DU) in the form of uranium hexafluoride (UF6), which is converted to uranium oxides. Depleted uranium dioxide (DUO2) can be used as a component of radiation shielding and as an absorbent for migrating radionuclides (especially 237Np and 99Tc). These may emerge from casks containing spent nuclear fuel (SNF) that are stored for hundreds of thousands of years in high-level wastes (HLW) and SNF repositories (e.g. Yucca Mountain Project). In this case DU oxides serve as an additional engi- neered chemical barrier. This work is a part of the joint Russian –American Program on Beneficial Use of Depleted Uranium. This paper describes the UO2 transformations that take place in contact with various aqueous media (deionized water (DW), J-13 solution that simulates Yucca Mountain ground water, etc.) and sorption of long-lived radionuclides (237Np and 99Тс) from these media by depleted uranium dioxide. Samples of depleted uranium dioxide used in this work originated from the treatment of UF6 in a reducing media to form UO2 (DUO2-1 at 600°C, DUO2-2 at 700°C, and DUO2-3 at 800°C).
    [Show full text]
  • HIGH HAZARD GAS Review Date: 09/23/2019
    University of Pittsburgh EH&S Guideline Number: 04-021 Safety Manual Subject: Effective Date: 04/19/2017 Page 1 of 9 HIGH HAZARD GAS Review Date: 09/23/2019 STORAGE AND USE OF HIGH HAZARD GAS 1. Definition of High Hazard (HH) Gases For these guidelines, any gas meeting one or more of the following definitions based on International Fire Code (IFC) and National Fire Protection Association (NFPA) standards: 1.1. Flammable gas – a material that is a gas at 68ºF (20ºC) or less at an absolute pressure of 14.7 psi (101.325 kPa) when in a mixture of 13% or less by volume with air, or that has a flammable range at an absolute pressure of 14.7 psi (101.325 kPa) with air of at least 12%, regardless of the lower limit 1.2. Pyrophoric gas – a gas with an autoignition temperature in air at or below 130ºF (54.4ºC) 1.3. Health Hazard 3 (HH3) gas – material that, under emergency conditions and according to the standards, can cause serious or permanent injury 1.4. Health Hazard 4 (HH4) gas – material that, under emergency conditions and according to the standards, can be lethal The storage and usage of a gas or gases meeting any of the above definitions must follow all applicable IFC and NFPA guidelines and the requirements outlined in this document. Consult EH&S for specific guidance on gas mixtures containing corrosive, flammable or poisonous gas components (ex. 1% carbon monoxide/nitrogen, 5% hydrogen sulfide/helium). 2. Notification Requirements Prior to Obtaining High Hazard Gases 2.1.
    [Show full text]