DOCSLIB.ORG

Redox Response of Actinide Materials to Highly Ionizing Radiation

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Redox Response of Actinide Materials to Highly Ionizing Radiation ARTICLE Received 9 Jul 2014 | Accepted 18 Dec 2014 | Published 27 Jan 2015 DOI: 10.1038/ncomms7133 Redox response of actinide materials to highly ionizing radiation Cameron L. Tracy1, Maik Lang2, John M. Pray3, Fuxiang Zhang3, Dmitry Popov4, Changyong Park4, Christina Trautmann5,6, Markus Bender5, Daniel Severin5, Vladimir A. Skuratov7 & Rodney C. Ewing8 Energetic radiation can cause dramatic changes in the physical and chemical properties of actinide materials, degrading their performance in fission-based energy systems. As advanced nuclear fuels and wasteforms are developed, fundamental understanding of the processes controlling radiation damage accumulation is necessary. Here we report oxidation state reduction of actinide and analogue elements caused by high-energy, heavy ion irradiation and demonstrate coupling of this redox behaviour with structural modifications. ThO2, in which thorium is stable only in a tetravalent state, exhibits damage accumulation 3 þ 4 þ processes distinct from those of multivalent cation compounds CeO2 (Ce and Ce ) and 4 þ 5 þ 6 þ UO3 (U ,U and U ). The radiation tolerance of these materials depends on the efficiency of this redox reaction, such that damage can be inhibited by altering grain size and cation valence variability. Thus, the redox behaviour of actinide materials is important for the design of nuclear fuels and the prediction of their performance. 1 Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA. 2 Department of Nuclear Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA. 3 Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, Michigan 48109, USA. 4 High Pressure Collaborative Access Team (HPCAT), Geophysical Laboratory, Carnegie Institution of Washington, Argonne, Illinois 60439, USA. 5 GSI Helmholtzzentrum fu¨r Schwerionenforschung, 64291 Darmstadt, Germany. 6 Technische Universita¨t Darmstadt, 64287 Darmstadt, Germany. 7 Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research, 141980 Dubna, Russia. 8 Department of Geological and Environmental Sciences, Stanford University, Stanford, California 94305, USA. Correspondence and requests for materials should be addressed to R.C.E. (email: [email protected]). NATURE COMMUNICATIONS | 6:6133 | DOI: 10.1038/ncomms7133 | www.nature.com/naturecommunications 1 & 2015 Macmillan Publishers Limited. All rights reserved. ARTICLE NATURE COMMUNICATIONS | DOI: 10.1038/ncomms7133 nsulating materials exhibit diverse responses to radiation, partially delocalized 5f orbitals cause significant variation in the ranging from isolated point defect formation and disordering accessible stable electronic configurations across this series21. Ito phase transformations and amorphization1. Substantial Motivated by the potential influence of their complex effort has been devoted to understanding the influence of crystal chemistry on the radiation response of actinide materials, we structure and chemistry on radiation damage accumulation2,3. have systematically irradiated f-block oxides with 167 MeV 132Xe The radiation tolerance of actinide materials, which refers to their ions, similar in mass and energy to fission fragments, and ability to retain their atomic structures and properties during 950 MeV 197Au ions. Fission rates are highest, and fission irradiation, is of primary concern for the design of nuclear fuels fragment damage most prevalent, in the relatively cool rim region with long operating lifetimes and adequate performance in of nuclear fuel pellets, where temperatures are typically between reactor accident scenarios4. A variety of criteria have been 500 and 700 °C, and thermal activation is generally negligible22. proposed as predictors of radiation tolerance, including bond Thus, these irradiations were performed at room temperature to covalency5, susceptibility to disordering2, thermodynamic avoid radiation-induced heating of the materials above fuel pellet stability6 and grain size7. However, relating trends in radiation rim temperatures. Complementary synchrotron-based structural tolerance to the dynamic process of radiation damage and chemical probes, X-ray diffraction (XRD) and X-ray accumulation is difficult due to the complex nature of defect absorption spectroscopy (XAS) were used to characterize the production and recovery, both of which occur at nanometric resulting atomic-scale modifications. Thorium and cerium are length scales, femto- and picosecond timescales, and extremely both nominally one f-electron elements and possess dioxides high energy densities8. In addition, the conditions under which a isostructural with those of the light actinides, all of which material is irradiated can drastically affect its response. High exhibit the fluorite structure, yet they possess contrasting solid- temperatures, as encountered in the centre of nuclear fuel pellets, state chemistry. ThO2, a proposed nuclear fuel component used can alter the kinetics of radiation-induced defect production, such for the breeding of uranium, cannot be reduced, while the cerium that materials that are tolerant of radiation in one temperature in the actinide analogue CeO2 is easily reduced from the regime can be less so in others9. Moreover, materials tolerant of tetravalent state to the trivalent state, similar to the behaviour low-energy radiation, which produces damage through atomic of UO2 and PuO2. Finally, UO3 and its room-temperature displacement caused by elastic collisions with nuclei, are not hydration products, (UO2)(OH)2 (a-uranyl hydroxide) and necessarily resistant to high-energy radiation, which deposits (UO2)8O2(OH)12(H2O)10 (metaschoepite), feature hexavalent energy in a material primarily through the excitation of uranium that can be reduced multiple steps to the tetravalent electrons10,11. The effects of highly ionizing radiation are oxidation state23. They are common oxidation/hydrolysis generally less well understood than those of displacive products of the nuclear fuel UO2 and are produced by fuel– radiation, but fission fragments, which fall into this high-energy coolant interactions and groundwater exposure of fuel4. regime, are known to significantly degrade the performance of The results of these experiments show evidence of coupling nuclear fuels12. To better understand the physics of damage between radiation-induced redox behaviour and structural production by ionizing radiation, a comprehensive approach, in modifications, with materials that undergo cation valence state which structural modifications are considered alongside coupled changes exhibiting damage accumulation behaviour different electron delocalization and redox processes, is necessary. than those that are resistant to such chemical modification. In We have investigated the effects of highly ionizing radiation on redox-active materials, control of the efficiency of these radiation- actinide materials using heavy ions accelerated to velocities induced redox processes through, for example, grain-size ranging from 5% to 10% the speed of light. At specific energies modification can be used to tailor the susceptibility of a material above B1 MeV per nucleon, these swift heavy ions simulate the to radiation damage. These results are particularly important for effects of the energetic nuclear fragments that form during fission actinide oxides as, due to the partially itinerant nature of their 5f events and the a-particles released in radionuclide decay, both of electrons, they exhibit increasing variability in stable electronic which deposit energy in irradiated materials primarily by configurations across the actinide series (as the 5f orbitals are electronic excitation13. Damage resulting from elastic collisions filled). This results in systematic variation in their radiation is generally minor until the particle end-of-range region, and the tolerance, as demonstrated here via a comparative study of such resulting defects are often distinct from those caused by the materials. These results yield new insight into the mechanisms by electronic interactions14. Electronic stopping results in extensive which highly ionizing radiation produces damage in nuclear fuel local ionization, yielding excitation densities of up to several materials and demonstrate potential for the design of radiation- keV nm À 3 within a nanometric cylinder along the ion tolerant materials through control of their redox behaviour. trajectory15. Although the atomistic modifications that occur following this electron cascade have been extensively studied8,13, the relaxation of these delocalized electrons is complex and Results 16 difficult to relate directly to atomic behaviour . It is generally Defect accumulation in ThO2. Irradiation of ThO2 with swift assumed that electron-hole recombination leads to recovery of the heavy ions induces only minor structural modifications pre-irradiation charge distribution13 but, given the highly non- (Fig. 1a,b), as discussed in detail elsewhere24. XRD patterns equilibrium conditions under which relaxation of the electron corresponding to both irradiation energies display a shift in the cascade occurs, electronic structure modifications are possible. Of fluorite structure diffraction maxima to lower 2y angles, particular interest is the influence of complex f-electron chemistry signifying an increase in the unit cell parameter and broadening on a material’s radiation response, considering previous work17,18 of the peaks due to the accumulation of heterogeneous reporting the reduction
Load more

Recommended publications
  • Recent Progress in the Membrane Distillation and Impact of Track-Etched Membranes
    polymers Review Recent Progress in the Membrane Distillation and Impact of Track-Etched Membranes Arman B. Yeszhanov 1,2, Ilya V. Korolkov 1,2 , Saule S. Dosmagambetova 1, Maxim V. Zdorovets 1,2,3,* and Olgun Güven 4,* 1 The Institute of Nuclear Physics, Ibragimov Str. 1, Almaty 050032, Kazakhstan; [email protected] (A.B.Y.); [email protected] (I.V.K.); [email protected] (S.S.D.) 2 L.N. Gumilyov Eurasian National University, Satbaev Str. 5, Nur-Sultan 010008, Kazakhstan 3 Ural Federal University, Mira Str. 19, Ekaterinburg 620002, Russia 4 Department of Chemistry, Hacettepe University, Ankara 06800, Turkey * Correspondence: [email protected] (M.V.Z.); [email protected] (O.G.); Tel.: +7-7-01-979-8859 (M.V.Z.); +90-31-2297-7977 (O.G.) Abstract: Membrane distillation (MD) is a rapidly developing field of research and finds applications in desalination of water, purification from nonvolatile substances, and concentration of various solutions. This review presents data from recent studies on the MD process, MD configuration, the type of membranes and membrane hydrophobization. Particular importance has been placed on the methods of hydrophobization and the use of track-etched membranes (TeMs) in the MD process. Hydrophobic TeMs based on poly(ethylene terephthalate) (PET), poly(vinylidene fluoride) (PVDF) and polycarbonate (PC) have been applied in the purification of water from salts and pesticides, as well as in the concentration of low-level liquid radioactive waste (LLLRW). Such membranes are Citation: Yeszhanov, A.B..; Korolkov, characterized by a narrow pore size distribution, precise values of the number of pores per unit area I.V..; Dosmagambetova, S.S..; and narrow thickness.
    [Show full text]
  • And Shape-Controlled Platinum Cones by Ion-Track Etching and Electrodeposition Techniques for Electrocatalytic Applications
    Article Fabrication of Size- and Shape-Controlled Platinum Cones by Ion-Track Etching and Electrodeposition Techniques for Electrocatalytic Applications Yuma Sato 1, Hiroshi Koshikawa 2, Shunya Yamamoto 2, Masaki Sugimoto 2, Shin-ichi Sawada 2 and Tetsuya Yamaki 1,2,* 1 Graduate School of Science and Technology, Gunma University, Kiryu 376-8515, Gunma, Japan; [email protected] 2 Takasaki Advanced Radiation Research Institute, National Institutes for Quantum and Radiological Science and Technology, Takasaki 370-1292, Gunma, Japan; [email protected] (H.K.); [email protected] (S.Y.); [email protected] (M.S.); [email protected] (S.-i.S.) * Correspondence: [email protected] Abstract: The micro/nanocone structures of noble metals play a critical role as heterogeneous electrocatalysts that provide excellent activity. We successfully fabricated platinum cones by elec- trodeposition using non-penetrated porous membranes as templates. This method involved the preparation of template membranes by the swift-heavy-ion irradiation of commercially available polycarbonate films and subsequent chemical etching in an aqueous NaOH solution. The surface diameter, depth, aspect ratio and cone angle of the resulting conical pores were controlled in the ranges of approximately 70–1500 nm, 0.7–11 µm, 4–12 and 5–13◦, respectively, by varying the etching Citation: Sato, Y.; Koshikawa, H.; conditions, which finally produced size- and shape-controlled platinum cones with nanotips. In Yamamoto, S.; Sugimoto, M.; Sawada, order to demonstrate the electrocatalytic activity, electrochemical measurements were performed for S.-i.; Yamaki, T. Fabrication of Size- and Shape-Controlled Platinum the ethanol oxidation reaction.
    [Show full text]
  • Novel Fission Track Detection for Identification and Characterization of Special Nuclear Materials
    University of Tennessee, Knoxville TRACE: Tennessee Research and Creative Exchange Doctoral Dissertations Graduate School 12-2017 Novel Fission Track Detection for Identification and Characterization of Special Nuclear Materials Jonathan Allen Gill University of Tennessee, Knoxville, [email protected] Follow this and additional works at: https://trace.tennessee.edu/utk_graddiss Part of the Nuclear Engineering Commons, and the Other Materials Science and Engineering Commons Recommended Citation Gill, Jonathan Allen, "Novel Fission Track Detection for Identification and Characterization of Special Nuclear Materials. " PhD diss., University of Tennessee, 2017. https://trace.tennessee.edu/utk_graddiss/4770 This Dissertation is brought to you for free and open access by the Graduate School at TRACE: Tennessee Research and Creative Exchange. It has been accepted for inclusion in Doctoral Dissertations by an authorized administrator of TRACE: Tennessee Research and Creative Exchange. For more information, please contact [email protected]. To the Graduate Council: I am submitting herewith a dissertation written by Jonathan Allen Gill entitled "Novel Fission Track Detection for Identification and Characterization of Special Nuclear Materials." I have examined the final electronic copy of this dissertation for form and content and recommend that it be accepted in partial fulfillment of the equirr ements for the degree of Doctor of Philosophy, with a major in Nuclear Engineering. Howard L. Hall, Major Professor We have read this dissertation and recommend its acceptance: Thomas T. Meek, Joseph R. Stainback IV, John D. Auxier Accepted for the Council: Dixie L. Thompson Vice Provost and Dean of the Graduate School (Original signatures are on file with official studentecor r ds.) Novel Fission Track Detection for Identification and Characterization of Special Nuclear Materials A Dissertation Presented for the Doctor of Philosophy Degree The University of Tennessee, Knoxville Jonathan Allen Gill December 2017 Copyright © 2017 by Jonathan A.
    [Show full text]
  • Carbon Nanocasting in Ion-Track Etched Polycarbonate Membranes
    Materials Letters 187 (2017) 56–59 Contents lists available at ScienceDirect Materials Letters journal homepage: www.elsevier.com/locate/matlet Carbon nanocasting in ion-track etched polycarbonate membranes ⁎ crossmark Xin Zhaoa,b, Falk Muencha, , Sandra Schaefera, Claudia Fasela, Ulrike Kunza, Sevda Ayatac, Shouxin Liub, Hans-Joachim Kleebea, Wolfgang Ensingera a Technische Universität Darmstadt, Department of Materials and Earth Sciences, Alarich-Weiss-Straße 2, 64287 Darmstadt, Germany b Northeast Forestry University, College of Material Science and Engineering, 150040 Harbin, PR China c Dokuz Eylul University, Science Faculty, Department of Chemistry, Tinaztepe Kampusu, Buca, 35160 Izmir, Turkey ARTICLE INFO ABSTRACT Keywords: We replicate the unique pore structure of ion-track etched polymers with carbon using an organic sol-gel Ion beam technology precursor strategy. First, phenol resin is cross-linked in the membrane pores, followed by selective dissolution Carbon materials of the template matrix and carbonization at a temperature of 550 °C. The potential to create nanomaterials of Template synthesis novel morphology is demonstrated by synthesizing free-standing, interconnected networks composed of aligned Pyrolysis carbon nanowires of defined or modulated diameter. Nanowire networks 1. Introduction These templates can be used to synthesize e.g. parallel arrays [9], networks or hierarchical assemblies [4] of 1D nano-objects. One-dimensional (1D) carbon structures such as nanotubes or Conventional template-assisted carbon deposition routes require nanowires (CNWs) represent one of the most important and frequently high-temperature processes such as chemical vapor deposition, and studied nanomaterial types. Due to their chemical, electrical, optical thus are limited to heat resistant templates such as anodized aluminum and mechanical properties, they can be employed in an exceptionally oxide [10], excluding ion-track etched polymers.
    [Show full text]
  • Multiple Activation of Ion Track Etched Polycarbonate for the Electroless Synthesis of Metal Nanotubes
    Appl Phys A (2011) 105:847–854 DOI 10.1007/s00339-011-6646-z Multiple activation of ion track etched polycarbonate for the electroless synthesis of metal nanotubes F. Muench · M. Oezaslan · T. Seidl · S. Lauterbach · P. Strasser · H.-J. Kleebe · W. Ensinger Received: 15 June 2011 / Accepted: 6 October 2011 / Published online: 4 November 2011 © Springer-Verlag 2011 Abstract In our study, we examined the formation of thin 1 Introduction films of silver nanoparticles on polycarbonate and the in- fluence of the silver loading on the electroless synthesis of In the early 1990s, Martin and coworkers developed several methods for the template-supported synthesis of metallic metal nanotubes. Control of the silver film thickness oc- micro and nanotubes (NTs), focusing on electroless plating curred by consecutive dipping of the polymer template in and ion track etched polycarbonate [1–3]. Ion track etched tin(II) and silver(I) solutions. The deposition progress was polymer templates contain stochastically distributed chan- studied using UV-Vis spectroscopy. The reaction mecha- nels whose density, diameter, and shape can be substantially nism relies on the adsorption of reactive ions on the poly- varied by the production conditions [4–6]. Wires and tubes mer template as well as on the silver nanoparticles. The are obtained by depositing metals in these channels [7–10]. initial catalytic activity of silver-covered ion track etched These virtually one-dimensional nanostructures have been effectively implemented in relevant fields such as nanoelec- polycarbonate is an important governing factor for the elec- trochemistry [3], field emission [7], selective chemical trans- troless synthesis of metal nanotubes with desired thickness port [8] and flow-through [9], or fuel cell [10] catalysis.
    [Show full text]
  • Ion-Track Technology Based Synthesis and Characterization of Gold and Gold Alloys Nanowires and Nanocones
    Ion-track technology based synthesis and characterization of gold and gold alloys nanowires and nanocones Vom Fachbereich Material- und Geowissenschaften der Technischen Universität Darmstadt zur Erklärung des akademischen Grades eines Doktors der Naturwissenschaften (Dr. rer. nat.) genehmigte Dissertation von Dipl. Ing. M.Sc. Loïc Burr aus Colmar (Frankreich) June 2016 - Darmstadt – D17 Ion-track technology based synthesis and characterization of gold and gold alloys nanowires and nanocones genehmigte Disseration von Dipl. Ing. M.Sc. Loïc Burr aus Colmar (Frankreich) 1. Gutachten: Prof. Dr. Christina Trautmann 2. Gutachten: Prof. Dr. Ralph Krupke Tag der Einreichung: 21.04.2016 Tag der mündlichen Prüfung: 21.04.2016 Darmstadt – 2016 D17 II | P a g e The work described in this thesis was carried out between November 2012 and June 2013 under the supervision of Prof. Dr. Trautmann at the Materials Research group of the GSI Helmholtz Centre for Heavy Ion Reseach, Plackstraße 1, D- 64291 Darmstadt, Germany Top cover image: colorized SEM image of Au nanowires standing on their Au backelectrode fabricated by electrodeposition in etched ion track templates as presented in this thesis Back cover image: modified SEM image of Au nanocones with their caps overlaying a nanocone array III | P a g e Erklärung zur Dissertation Hiermit versichere ich, die vorliegende Dissertation ohne Hilfe Dritter und nur mit den angegebenen Quellen und Hilfsmitteln angefertigt zu haben. Alle Stellen, die aus den Quellen entnommen wurden, sind als solche kenntlich gemacht worden. Diese Arbeit hat in dieser oder ähnlicher Form noch keiner Prüfungsbehörde vorgelegen. Darmstadt, den 19.04.2016 _________________________________ (Loïc Burr) Loïc Burr Ion-track technology based synthesis and characterization of gold and gold alloys nanowires and nanocones PhD Thesis, Technische Universität Darmstadt, Darmstadt, Germany URN: urn:nbn:de:tuda-tuprints-55410 URI: http://tuprints.ulb.tu-darmstadt.de/id/eprint/5541 Copyright © 2016 by L.
    [Show full text]
  • Fullerene Irradiation Leading to Track Formation Enclosing Nitrogen Bubbles in Gan Material J.G
    Fullerene irradiation leading to track formation enclosing nitrogen bubbles in GaN material J.G. Mattei, M. Sall, F. Moisy, A. Ribet, E. Balanzat, C. Grygiel, I. Monnet To cite this version: J.G. Mattei, M. Sall, F. Moisy, A. Ribet, E. Balanzat, et al.. Fullerene irradiation leading to track formation enclosing nitrogen bubbles in GaN material. Materialia, Elsevier, 2021, 15, pp.100987. 10.1016/j.mtla.2020.100987. hal-03162888v2 HAL Id: hal-03162888 https://hal.archives-ouvertes.fr/hal-03162888v2 Submitted on 2 Apr 2021 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Fullerene irradiation leading to track formation enclosing nitrogen bubbles in GaN material JG Mattei, M. Sall, F. Moisy, A. Ribet, E. Balanzat, C. Grygiel, and I. Monnet* CIMAP, CEA-CNRS-ENSICAEN-Normandie Université BP5133 F-14070 Caen cedex5 France. * Corresponding author: [email protected] Abstract Gallium nitride was irradiated with fullerene projectiles having an electronic stopping power above the threshold required to promote ion track formation. The structural and chemical changes induced by fullerene irradiation were studied through Transmission Electron Microscopy (TEM). High resolution TEM inquiries were performed to identify the structural order along the ion tracks and the strain induced in the lattice neighboring the ion tracks.
    [Show full text]
  • Separation of Radioactive Elements from Rare Earth Element-Bearing Minerals
    metals Review Separation of Radioactive Elements from Rare Earth Element-Bearing Minerals Adrián Carrillo García 1, Mohammad Latifi 1,2, Ahmadreza Amini 1 and Jamal Chaouki 1,* 1 Process Development Advanced Research Lab (PEARL), Chemical Engineering Department, Ecole Polytechnique de Montreal, C.P. 6079, Succ. Centre-ville, Montreal, QC H3C 3A7, Canada; [email protected] (A.C.G.); mohammad.latifi@polymtl.ca (M.L.); [email protected] (A.A.) 2 NeoCtech Corp., Montreal, QC H3G 2N7, Canada * Correspondence: [email protected] Received: 8 October 2020; Accepted: 13 November 2020; Published: 17 November 2020 Abstract: Rare earth elements (REE), originally found in various low-grade deposits in the form of different minerals, are associated with gangues that have similar physicochemical properties. However, the production of REE is attractive due to their numerous applications in advanced materials and new technologies. The presence of the radioactive elements, thorium and uranium, in the REE deposits, is a production challenge. Their separation is crucial to gaining a product with minimum radioactivity in the downstream processes, and to mitigate the environmental and safety issues. In the present study, different techniques for separation of the radioactive elements from REE are reviewed, including leaching, precipitation, solvent extraction, and ion chromatography. In addition, the waste management of the separated radioactive elements is discussed with a particular conclusion that such a waste stream can be
    [Show full text]
  • Pro Sto A02 Msds 002 Msds Pi Membrane
    MATERIAL SAFETY DATA SHEET MSDS003 - MSDS - Version 06 POLYIMIDE (PI) Date 01/06/21 TRACK-ETCHED MEMBRANE Page 1/6 ION TRACK TECHNOLOGY SECTION 1 : COMPANY INFORMATION ............................................................................................................. 2 MANUFACTURER / DISTRIBUTOR 2 MSDS MANAGER 2 SECTION 2 : COMPOSITION / INFORMATION ON INGREDIENTS ................................................................. 2 SECTION 3 : HAZARD IDENTIFICATION / EMERGENCY OVERVIEW .......................................................... 2 APPEARANCE 2 CLASSIFICATION 2 ADVERSE HUMAN HEALTH EFFECTS 2 TARGET ORGANS 2 MEDICAL CONDITIONS AGGRAVATED BY EXPOSURE 2 SECTION 4 : FIRST AID MEASURES .................................................................................................................... 3 CONTACT WITH EYES 3 INGESTION 3 INHALATION 3 SKIN CONTACT 3 SECTION 5 : FIRE FIGHTING MEASURES ........................................................................................................... 3 SUITABLE EXTINGUISHING MEDIA 3 SPECIFIC HAZARDS WITH REGARD TO FIRE-FIGHTING MEASURES 3 SPECIFIC FIRE-FIGHTING MEASURES 3 SPECIFIC FIRE-FIGHTING MEASURES 3 SECTION 6 : ACCIDENTAL RELEASE MEASURES ........................................................................................... 4 PERSONAL PRECAUTIONS 4 SMALL AND LARGE SPILLS 4 ADVERSE ENVIRONMENTAL AND PHYSIOCHEMICAL EFFECTS 4 CLEAN UP MEASURES 4 SECTION 7 : HANDLING AND STORAGE ..........................................................................................................
    [Show full text]
  • Cooperative Effect of Electronic and Nuclear Stopping on Ion Irradiation
    Cooperative effect of electronic and nuclear stopping on ion irradiation damage in silica M Backman1;2, F Djurabekova2, O H Pakarinen2, K Nordlund2, Y Zhang3;1, M Toulemonde4 and W J Weber1;3 1 Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA 2 Helsinki Institute of Physics and Department of Physics, P.O. Box 43, FI-00014 University of Helsinki, Finland 3 Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA 4 CIMAP-CEA-CNRS-ENSICAEN-University of Caen, F-14070 Caen Cedex 5, France E-mail: [email protected] Abstract. Radiation damage by ions is conventionally believed to be produced either by displacement cascades or electronic energy deposition acting separately. However, there is a range of ion energies where both processes are significant and could contribute to irradiation damage. The combination of two computational methods, namely binary collision approximation and molecular dynamics, the latter with input from the inelastic thermal spike model, makes it possible to examine the simultaneous contribution of both mechanisms of energy deposition on the structural damage in the irradiated structure. We study the effect in amorphous SiO2 irradiated by Au ions with energies ranging between 0.6 and 76.5 MeV. We find that in the intermediate energy regime, there is a synergistic effect of local heating due to electronic excitations in enhancing the displacement cascade damage. PACS numbers: 61.80.Jh, 61.43.Bn, 61.43.Fs Cooperative effect of electronic and nuclear stopping 2 1. Introduction Ion irradiation of solids is a topic that is studied both as a tool for materials modification and as a source of damage to materials in, for instance, nuclear reactors.
    [Show full text]
  • United States Patent Office 2,988,421
    United States Patent Office Patented June2,988,421 13, 196 heavailaaaar 1 2 contain more than 200 gms. alkali metal and chloride ions 2,988,421 per litre. The following tables show the loss of thorium PROCESS FOR THE SEPARATION OF THORUM and lanthanons under various conditions in the presence WilliamANDRARE Palmer Kemp, EARTHS Shenfield, FROM and MONAZTE James Johnston, 5 of sodium and potassium chloride. Hainault, England, assignors to Thorium Limited, Lon don, England, a corporation of Great Britain NaCl, ThO Ln2O No Drawing. Filed Aug. 20, 1957, Ser. No. 679,126 Acidity gm.fl. loss, loss, Claim priority, application Great Britain Aug. 24, 1956 gm.fl. gm.fl. 9 Claims. (C. 23-145) -ror-rm-m-m------- 10 : 122 This invention relates to a process for separating thori- 4.5 8: um and lanthanon salts from other materials present in : g monazite. The invention is particularly useful in that it 55 i. provides a process for separating salts of thorium and the : 8. lanthanons from phosphate and impurities present in 1655 400 6.65 ground mineral monazite. The term lanthanon in this specification includes the elements with atomic numbers KC ThO Ln2O from 57-71; this group is also known as the rare earth Acidity fi. is is elements. gm.fl. gm.fl. Monazite sand is a mineral phosphate containing thori- .am-m-m-m-m-m-m-wn um and the lanthanon phosphates to the extent of about 38 o' 95-98% by weight. Another source is ground mineral 300 0.005 1.0 monazite which is far less pure than monazite sand and contains only about 75% of the thorium and lanthanon In a preferred form of the process the filtered extract phosphates.
    [Show full text]
  • NSF-EC Workshop on Nanomaterials and Nanotechnology Summary Report
    NSF-EC Nanomaterials Workshop 2002 NSF-EC Workshop on Nanomaterials and Nanotechnology Summary Report I. Workshop Overview The NSF-EC workshop on nanomaterials and nanotechnology was held in Boston, Massachusetts on December 5-7 2002. Both the US and the EC realize the importance of a globally trained technical workforce. A focused effort to enhance interactions between the U.S. and E.C. in scientific research is one important way to create a culture where international cooperation is the rule rather than the exception. This workshop was developed to provide important feedback to NSF and EC on two issues: I) The most critical and timely issues facing those investigators developing new nanomaterials and technologies related to those materials and II) The best practices for catalyzing cooperative research in the emerging area of nanomaterials. Appendix A provides a list of attendees while Appendix B gives the program and talk titles. Recommendations for important topics and challenges in nanomaterials research were arrived at by discussions in breakout groups in each of the three topical theme areas of the work. These discussions were preceded by brief talks from each of the participants. The common themes found in this discussion: • An increased focus on developing materials which have multifunctional capabilities. Nanoparticles that can both sense and treat disease for example, devices that leverage both the optical and electronic properties of nanoparticles assemblies, or functional coatings whose biodegradation can be triggered after a certain time. • Recognition of the importance that the environmental impact of nanomaterials in developing sustainable nanotechnologies. Very little is known about how nanomaterials interact with animals and the larger environment.
    [Show full text]