DOCSLIB.ORG

Progress in Nuclear Waste Vitrification by Ceramic Melter Technique

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Progress in Nuclear Waste Vitrification by Ceramic Melter Technique JP9950237 PROGRESS IN NUCLEAR WASTE VITRIFICATION BY CERAMIC MELTER TECHNIQUE S. WEISENBURGER Forschungszentrum Karlsruhe Institut fur Nukleare Entsorgungstechnik P.O.BOX 3640, 76021 Karlsruhe, Germany ABSTRACT Nuclear waste vitrification by using the liquid-fed ceramic-lined waste glass melter process started in 1973 with the pioneering development at Batelle Pacific Northwest Laboratory. The first radioactive plant applying this technique was the PAMELA plant in Mol/ Belgium which was put into hot operation in 1985. A main part of the technology for this plant including the melter was developed by the Institut fur Nukleare Entsorgungstechnik (INE) of Forschungszentrum Karlsruhe (FZK)! For the time being there is an increasing demand for the availability of small-scale vitrification units for processing of small stocks of high level liquid wastes (HLLW). Limited quantities of HLLW solutions were obtained during the period of development of reprocessing techniques at various international sites. One example is the former WAK (Wiederaufarbeitungs-anlage Karlsruhe) reprocessing plant. It is located at the site of Forschungszentrum Karlsruhe and is now under decommissioning. The overall decommissioning program includes vitrification of 70 m3 of stored HLLW with a total p7y radioactivity of 8.9 x E17 Bq. This paper focuses on progress achieved in the design of small-scale liquid-fed ceramic glass melters for these purposes. Improvements are described regarding extension of power electrode life time by optimized air cooling, glass pouring operation, off-gas pipe cleaning, glass level detection system in the melt tank, and arrangement of a small-scale melter in a hot a cell. Some test results achieved with the new melter are also outlined. INTRODUCTION Ceramic-lined waste glass melters are currently in use in several radioactive vitrification plants like Tokai Vitrification Facility in Japan, Savannah River Defence Waste Processing Facility, and West Valley Demonstration Plant in the US. The PAMELA plant, using this technique as well vitrified 907 m3 of high level waste into 4901 of radioactive waste glass between 1985 and 1991. In Germany the development of the vitrification technology is currently focused on the special aspects of wastes stored at former nuclear reprocessing sites. These include mainly (1) appropriate simplification and scale down of the vitrification system while maintaining or even improving the functional safety, and (2) keeping the overall plant size and thus costs as low as possible particularly in view of the usually limited waste volume to be processed and, hence the short operation time. The VEK-project (Verglasungseinrichtung Karlsruhe) is one example of application of a small-scale vitrification plant for conditioning of small HLLW stocks stored at reprocessing sites under decommissioning [1]. A prototype non-radioactive test facility with such features was designed in 1995 at the Institut fur Nukleare Entsorgungstechnik (INE) of the Forschungszentrum Karlsruhe. After two years of construction the facility has been put into operation in May 1998. The paper outlines the progress which had been achieved referred to the glass melting system. Improvements are described concerning extension of power electrode life time, glass pouring operation, noble metals compatibility, off-gas pipe cleaning, glass level detection in the glass pool, and optimised arrangement of the melter in the hot cell. - 241 - JAERI-Conf 99-004 SMALL-SCALE MELTER TECHNOLOGY The process of converting high-level liquid waste into glass in a liquid-fed ceramic melter is characterized by the fact that individual process steps of vitrification (drying, calcining, and reaction of the waste residue with glass formers) take place simultaneously within the glass melter (Fig. 1). HLLW and glass forming additives - glass frit in the form of beads - are directly fed onto the hot glass melt surface. Vitrification occurs in a limited reaction layer formed on the melt pool surface. The glass melt is current-heated through immersed electrodes according to the Joule principle. The melting tank is thermally insulated and the whole system is encased by a stainless steel containment box. The off-gas leaving the melter through a melter roof nozzle is cleaned in a multistage off-gas treatment system and contains water steam, NOx, particles, volatiles and inleakage air. The melter type developed for use in a small-scale vitrification facility is a conspicuous novelty in melter technology. The design and characteristics of the small-scale glass melter can be seen in Fig. 2. The novel type features cylinder shape, bottom drain (no additional glass overflow system) and reduced size which was primarily achieved by a reduced melt tank content, and substantial simplifications concerning the glass heating system. The compact melter design has considerable impacts on the size of the melter cell, the arrangement of the melter within this cell, and the remote handling technique. The melter has a design throughput of 12 1/h corresponding to a glass production rate of approximately 8.5 kg/h. The glass tank made of high temperature resistant ceramic refractory contains about 150 1 glass melt which corresponds to the volume capacity of one canister with a glass capacity of 400 kg and dimensions 430 mm in dia. and 1335 mm height. The main features of the melt tank are its sloped side walls and the bottom design. The slope forces the noble metals High active ^Gl^frit liquid waste ^ Stainless steel box Alternating el. current -50 Hz <J=" Cooling air pouring channel Canister Fig. 1: Simplified scheme of the liquid-fed ceramic melter process - 242 - lAERI-Conf 99-004 CZZJ Fig. 2: Layout and characteristics of INE's today small-scale melter technology Melter outside dimension: 1500 mm in diameter, 1700 mm height Table 1: Main characteristics of the small-scale glass melter Characteristic Data Nominal throughput 121/h Glass production rate 8.5kg/h Glass pool surface 0.44 m2 Melt tank content 1501 Residence time of glass in the pool 44 h Glass pool heating Direct electric heating Heating power release 40 kW maximum Glass pouring system Bottom drain Quantity of glass per pouring 100 kg, flow rate appr. 100-130 kg/h Frequency of pouring Every 11-12 h Melter size 1.5 m dia., 1.7 m height Weight 8.5 t - 243 - JAERI-Conf 99-004 ruthenium, palladium and rhodium - not soluble in the borosilicate melt and settling to the melter floor - to flow towards the glass discharge area at the melt tank bottom. A special glass channel design in the discharge zone assures the complete outflow of any noble metal sludges arriving in this area. The melt is heated in the melt tank center to !200°C by a single pair of electrodes made of high temperature resistant INCONEL 690. Towards the side walls and the melter bottom, temperature drops between 100-200°C exist. Additional energy can be released, if needed, by a pair of auxiliary electrodes installed in the bottom area of the melt tank. The first melter start-up and also restarts are performed by means of several external SiC-resistance heaters introduced temporarily through openings in the melter roof. At sufficiently high temperatures the electric conductivity of the glass for direct heating is attained. For discharge of the glass the melter is equipped with a draining system at its bottom. The system works on the principle of a thermal valve. For initiation of pouring, the glass solidified in the discharge channel is remelted by external energy supply from two heating systems (direct electric heating and medium frequency induction heating of the pouring pipe). The glass flow rate of approximately 120 kg/h is controlled via energy input of the pipe heating. The flow rate is measured by monitoring the weight increase of the canister vs. time. Some characteristic data of this small- scale melter design are summarised in Table 1. IMPROVEMENTS IN MELTER DESIGN Improvements of the melter design has been made in recent years. They refer to the extension of electrode lifetime by an improved air-cooling, to the glass pouring system and its operation mode, to the cleaning of the melter off-gas pipe, and to a reliable glass level detection system in the melter. Extension of power electrode life time The life time of the power electrodes is an important factor of the overall life time of the melter system. The submerged surface of the INCONEL 690 power electrodes undergoes only negligible corrosion attack by the glass melt as long as the surface is at or below approximately 1000°C. The details of corrosion mechanism and kinetics and the impact of temperature had been investigated and reported in Ref. [2]. The air cooling of the electrodes of the small-scale melter has been optimised in order to keep the submerged electrode surface at or below 1000°C. The cooling air (flow rate around 20 m3/h each electrode) is released into the melter cell after passing the air cooling channels of the electrode. Air cooling lowers the submerged electrode surface temperature by approximately 100°C compared to non-cooling. The results of numerical modelling of the melter system confirms the experimental data. Fig. 3 gives the numerical modelling results of the isotherms in the power electrode area under conditions of air-cooling compared to non-air-cooling conditions. Thus, permanent air-cooling during glass production operation extends the life time of the power electrodes considerably. At INE, a melter is in use since more than 8 years without indications of significant corrosion attack of the air-cooled power electrodes. Glass pouring system Glass pouring into the stainless steel canisters is one of the most important steps in HLLW vitrification. It requires a system with a safe function and a long service life. It must be compatible with the service life of other main components of the melter like the ceramic refractory material of the glass tank/melter plenum, or the power electrodes.
Load more

Recommended publications
  • Nuclear Waste Vitrification Efficiency: Cold Cap Reactions
    Journal of Non-Crystalline Solids 358 (2012) 3559–3562 Contents lists available at SciVerse ScienceDirect Journal of Non-Crystalline Solids journal homepage: www.elsevier.com/ locate/ jnoncrysol Nuclear waste vitrification efficiency: Cold cap reactions P. Hrma a,b,⁎, A.A. Kruger c, R. Pokorny d a Division of Advanced Nuclear Engineering, Pohang University of Science and Technology, Pohang, Republic of Korea b Pacific Northwest National Laboratory, Richland, WA 99352, USA c U.S. Department of Energy Hanford Tank Waste Treatment and Immobilization Plant Federal Project Office, Engineering Division, Richland, WA 99352, USA d Institute of Chemical Technology, Prague, Czech Republic article info abstract Article history: Batch melting takes place within the cold cap, i.e., a batch layer floating on the surface of molten glass in a Received 26 July 2011 glass-melting furnace. The conversion of batch to glass consists of various chemical reactions, phase transi- Received in revised form 5 January 2012 tions, and diffusion-controlled processes. This study introduces a one-dimensional (1D) mathematical Available online 7 March 2012 model of the cold cap that describes the batch-to-glass conversion within the cold cap as it progresses in a vertical direction. With constitutive equations and key parameters based on measured data, and simplified Keywords: boundary conditions on the cold-cap interfaces with the glass melt and the plenum space of the melter, Glass melting; Glass foaming; the model provides sensitivity analysis of the response of the cold cap to the batch makeup and melter con- Waste vitrification; ditions. The model demonstrates that batch foaming has a decisive influence on the rate of melting.
    [Show full text]
  • Final Vitrification Melter Evaluation
    Waste-Incidental-to-Reprocessing Evaluation for the West Valley Demonstration Project Vitrification Melter February 2012 Prepared by the U.S. Department of Energy West Valley, New York This page is intentionally blank. WASTE-INCIDENTAL-TO-REPROCESSING EVALUATION FOR THE WVDP VITRIFICATION MELTER CONTENTS NOTATION (Acronyms, Abbreviations, and Units).................................................. v 1.0 INTRODUCTION ...................................................................................................... 1 1.1 Purpose. ................................................................................................................. 2 1.2 Scope and Technical Basis ....................................................................................... 2 1.3 Consultation and Opportunity for Public Review ........................................................ 3 1.4 Background ............................................................................................................ 4 1.4.1 The Western New York Nuclear Service Center .............................................. 4 1.4.2 Spent Nuclear Fuel Processing ...................................................................... 6 1.4.3 The West Valley Demonstration Project ......................................................... 7 1.4.4 Characterization of the Vitrification Melter ..................................................... 7 1.4.5 Incorporation into a Solid Physical Form ........................................................ 8 1.4.6 Potential Waste Disposal
    [Show full text]
  • Vitrification of Ion-Exchange (IEX) Resins: Advantages and Technical Challenges
    WSRC-MS-95-0518 Vitrification of Ion-Exchange (IEX) Resins: Advantages and Technical Challenges bv C. M. Jantzen Westinghouse Savannah River Company Savannah River, Site Aiken, South Carolina 29808 D. K. Paster G. A. Cicero A document prepared for AMERICAN CERAMIC SOCIETY ANNUAL MEETING, NUCLEAR DIVISION at Indianapolis frorrt 04/14/95 - 04/17/95. DOE Contract No. DE-AC09-89SR18035 This paper was prepared in connection with work done under the above contract number with the U. S. Department of Energy. By acceptance of this paper, the publisher and/or recipient acknowledges the U. S. Government's right to retain a nonexclusive, royalty-free license in and to any copyright covering this paper, along with the right to reproduce and to authorize others to reproduce all or part of the copyrighted paper. DISCLAIMER This report was prepared as an account of work sponsored by an agency of the United States Government Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed,.or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.
    [Show full text]
  • Transformation (T TT) Diagram for EPY® Epoxy System
    18 2018, 63, nr 1 Glass transition temperature-cure temperature- ® -transformation (TgTT) diagram for EPY epoxy system Magdalena Urbaniak1) DOI: dx.doi.org/10.14314/polimery.2018.1.3 Abstract: The EPY® epoxy system applied for the production of machine foundation chocks was iso- thermally cured at varying cure temperatures and times. The thermal behavior during the curing of the system was monitored by means of the glass transition temperature (Tg) and conversion degree (α) measured using differential scanning calorimetry (DSC) and rotational viscometry (ARES). Also, the thermal decomposition was measured by thermogravimetry and differential thermal analysis (TG-DTA). The results were analyzed and summarized in the generalized phase diagram, as well as in the Tg-cure temperature-transformation (TgTT) cure diagram. The phase diagram has reference to the transformations (in liquid, ungelled glass, gelled glass and rubber state) encountered at time to gelation and vitrification. Whereas theT gTT diagram shows that there are three types of behavior related to the temperature of cure and makes a useful framework for understanding and analyzing the relations and interdependencies during the curing process of the epoxy system. Keywords: epoxy system, curing, gelation, vitrification, glass transition temperature, glass transition temperature-cure temperature-transformation diagram. Diagram temperatura zeszklenia-temperatura sieciowania-przemiana (TgTT) dla układu epoksydowego EPY® Streszczenie: Próbki układu epoksydowego EPY®, używanego do wytwarzania podkładek funda- mentowych maszyn, sieciowano izotermicznie stosując różne temperatury i różny czas sieciowania. Metodami różnicowej kalorymetrii skaningowej (DSC) i wiskozymetrii rotacyjnej (ARES) zbadano przemiany tak przygotowanych układów pod wpływem zmian temperatury wyznaczając temperaturę zeszklenia (Tg) i stopień konwersji (α). Badano także rozkład termiczny próbek za pomocą symulta- nicznej termograwimetrycznej i różnicowej analizy termicznej (TG-DTA).
    [Show full text]
  • To Make a Glass – Avoid the Crystal
    To make a glass – avoid the crystal Thomas Palberg1, Eckhard Bartsch2, Richard Beyer1, Maximilian Hofmann1, Nina Lorenz1,3, Janina Marquis1, Ran Niu1,4 and Tsuneo Okubo5 Abstract Colloidal model systems allow for a flexible tuning of particle sizes, particle spacings and mutual interactions at constant temperature. Colloidal suspensions typically crystallize as soon as the interactions get sufficiently strong and long-ranged. Several strategies have been successfully applied to avoid crystallization and instead produce colloidal glasses. Most of these amorphous solids are formed at high particle concentrations. This paper shortly reviews experimental attempts to produce amorphous colloidal solids using strategies based on topological, thermodynamic and kinetic considerations. We complement this overview by introducing a (transient) amorphous solid forming in a thoroughly deionized aqueous suspension of highly charged spheres at low salt concentration and very low volume fractions. Key words: colloidal model systems, colloidal glasses, structural glasses, light scattering, crystal nucleation, polydispersity, eutectic phases, frustration, dynamic arrest, Thomas Palberg [email protected] 1 Institute of Physics, Johannes Gutenberg University, D-55099 Mainz, Germany 2 Institute of Physical Chemistry, Albert-Ludwigs-University, D-79104 Freiburg, Germany 3 present address: Sentronics Metrology, Mannheim, Germany 4 on leave from: Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China 5 Institute for Colloidal Organization, Hatoyama 3-1-112 Uji, Kyoto 611-0012, Japan Introduction Colloidal suspensions are well known experimental model systems to study the structural and dynamic properties of condensed matter [1, 2, 3, 4]. Typically, spherical particles of sub- micron size suspended in a liquid carrier medium are studied as a model for simple atomic solids and liquids [5].
    [Show full text]
  • Development of a Glass Matrix for Vitrification of Sulphate Bearing High
    BACKGROUND Radioactive waste is generated during various steps of nuclear fuel cycle viz. mining and milling of uranium ore, fuel fabrication, reactor operations and spent fuel reprocessing. In India, a closed loop option has been adopted where spent fuel is reprocessed to recover plutonium and un-used uranium. The typical Indian nuclear fuel cycle is presented in Fig-1. The majority of radioactivity in the entire nuclear fuel cycle is concentrated in high level radioactive waste (HLW), which is generated during reprocessing of spent nuclear fuel. Three stage strategy adopted for management of HLW includes - (i) immobilization of waste in stable and solid matrix, (ii) interim storage of conditioned waste product and (iii) deep underground disposal in geological formations. Borosilicate glass system has been adopted world-wide as a matrix for immobilization of HLW [1]. The presently stored HLW at Trombay is characterised by significant concentration of uranium, sodium and sulphate in addition to fission products, corrosion products and small amount of other actinides. Sulphate in the waste is derived from ferrous sulphamate used as a reducing agent for conversion of Pu+4 to Pu+3 during partitioning stage of reprocessing and is one of the troublesome constituent with respect to vitrification. Sulphate in the form of sodium sulphate can be accommodated in borosilicate matrix only to a limited extent i.e. 1 wt% maximum [2]. At higher sulphate concentrations, a separate phase of alkali sulphate known as “gall” is formed. Its presence in the glass is not desirable as this phase is enriched with Cs and has high solubility in water.
    [Show full text]
  • 18O Diffusion Through Amorphous Sio2 and Cristobalite J
    18O diffusion through amorphous SiO2 and cristobalite J. RodríguezViejo, F. Sibieude, M. T. ClavagueraMora, and C. Monty Citation: Applied Physics Letters 63, 1906 (1993); doi: 10.1063/1.110644 View online: http://dx.doi.org/10.1063/1.110644 View Table of Contents: http://scitation.aip.org/content/aip/journal/apl/63/14?ver=pdfcov Published by the AIP Publishing This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitation.aip.org/termsconditions. Downloaded to IP: 158.109.223.71 On: Fri, 28 Feb 2014 09:54:08 180 diffusion through amorphous SiOs and cristobalite J. Rodriguez-Viejoa) and F. Sibieude Institut des Sciences et de G&ie des Matgriaux et Pro&d& C. N. R.S. BP 5, Odeillo, 66120 Font-Romeu, France M. T. Clavaguera-Mora Fisica de Materiales, Departamento de Fisica, Universidad Aut6noma de Barcelona, 08193 Bellaterra, Spain C. Monty Laborafoire de Physique des Matkriaux, C. N. R.S., I Place Aristide Briand, Beilevue, 92195 Meudon, Cedex, France (Received 26 January 1993; accepted for publication 6 July 1993) Secondary ion mass spectrometry was used to profile the diffusion of oxygen in polycrystalline P-cristobalite and vitreous SiOz. The tracer concentration profiles of cristobalite are consistent with a model based on two mechanisms: bulk and short-circuit diffusion. The profiles of partially crystallized samples containing vitreous SiOa and /3cristobalite were fitted using the sum of two complementary error functions and taking account of some interstitial-network exchange. The bulk oxygen diffusivity, in the temperature range 1240-1500 “C, is about five times greater for vitreous silica than for fl-cristobalite.
    [Show full text]
  • 22 Vitrification in Tissue Preservation: New Developments
    TF1231_C22.fm Page 603 Tuesday, April 6, 2004 11:13 PM Vitrification in Tissue 22 Preservation: New Developments Michael J. Taylor, Ying C. Song, and Kelvin G.M. Brockbank CONTENTS 22.1 Introduction ........................................................................................................................604 22.2 Background and Historical Perspective.............................................................................605 22.3 Evidence that Extracellular Ice Is Harmful.......................................................................606 22.4 Approaches to Ice-Free Cryopreservation.........................................................................608 22.4.1 Equilibrium Approach .........................................................................................608 22.4.2 Nonequilibrium Approach—Vitrification............................................................609 22.4.2.1 Stability of the Amorphous State .......................................................611 24.4.2.2 Material Properties and Cracking.......................................................612 24.4.2.3 Thermomechanical Stress during Cryopreservation of Tissues.........612 22.4.3 Alternative Strategies for Achieving Vitreous Cryopreservation........................615 22.4.4 Ice-Growth Inhibitors ..........................................................................................615 22.4.5 Preliminary Physical Studies on the Effect of Synthetic Ice Blocking Molecules.............................................................................................................616
    [Show full text]
  • The Function of Time in the Vitrification of Clays
    DEPARTMENT OF COMMERCE Technologic Papers of THE Bureau of Standards S. W. STRATTON, Director No. 17 THE FUNCTION OF TIME IN THE VITRIFICATION OF CLAYS BY G. H. BROWN, Assistant Ceramic Chemist and G. A. MURRAY, Laboratory Assistant Bureau of Standards [MAY 20, 1913] WASHINGTON GOVERNMENT PRINTING OFFICE 1913 . THE FUNCTION OF TIME IN THE VITRIFICATION OF CLAYS By G. H. Brown and G. A. Murray CONTENTS Page i. Introduction 3 (a) General statement 3 (b) Previous work 4 2. Description of work 6 3 Discussion of results 7 (a) Galesburg paving-brick shale 7 (6) Cleveland paving-brick shale 11 (c) Canton paving-brick shale 13 (d) Urbana surface clay 15 (e) Heron Lake surface clay 18 (/) West Decatur No. 3 fire clay 19 4. Cone-softening temperatures 22 5. Summary 25 1. INTRODUCTION (a) General Statement.—It is a well-known fact that time is an exceedingly important factor in the maturing of clays and bodies. A certain result may be obtained either by the use of a higher temperature for a shorter time or a lower temperature for a longer time. This fact we see constantly illustrated in the firing of all kinds of clay products, the melting of glass, the soften- ing of pyrometric cones, etc. Yet there are definite thermal limits to which such relations are confined. These correspond to the lowest temperature at which partial softening, which is a nec- essary condition of vitrification, can take place. It should be recognized also that the closing up of the pore system is not entirely due to the action of fluxes.
    [Show full text]
  • Vitrification (Freezing)
    VITRIFICATION (FREEZING) Vitrification of oocytes and blastocysts is the process by which the solution containing the oocyte or embryo is cooled so rapidly that the water molecules do not have the time to form ice crystals and instantly solidify into a “glass-like” structure. VITRIFICATION (FREEZING) This concept is based upon the idea that if the cell is dehydrated to a certain degree and then cooled fast enough, The first human pregnancy from a everything will “freeze” in place and damage will not have frozen and subsequently thawed time to occur; crystals will not be able to organize themselves embryo was achieved in Australia and a vitrified amorphous, a glass-like solid, will form instead in 1984. The method used to of ice. Vitrification cools the embryos an amazing 7,000 times preserve that embryo is called faster than conventional slow freezing techniques (2,000- “slow freezing” and it is still the 2,500 Celsius per minute). Since no ice forms, the risk of preferred method for preserving rupturing the cell is reduced. embryos throughout the world today. Slow freezing is a reliable Vitrification involves exposure of the cell to high concentrations and established technique that has of cryoprotectants for brief periods of time, followed by rapid cooling by touching a block which has been cooled in liquid served the IVF community well for over 20 years. nitrogen. The high osmolarity of the vitrification solution rapidly Slow-freezing cools the embryos gradually, approximately dehydrates the cell and liquid nitrogen quickly solidifies the cell - 0.3° C /minute until it has been cooled to below -30° C and so that the remaining intracellular water does not have time to is therefore fully frozen.
    [Show full text]
  • Bulk Vitrification Castable Refractory Block Protection Study
    PNNL-15193 Bulk Vitrification Castable Refractory Block Protection Study P. Hrma J. Matyas L.M. Bagaasen K.B.C. Minister A.E. Beck M.J. Schweiger T.M. Brouns D.M. Strachan D.D. Caldwell B.P. Tinsley M.L. Elliott G.W. Hollenberg April 2005 Prepared for the U.S. Department of Energy under Contract DE-AC05-76RL01830 DISCLAIMER This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor Battelle Memorial Institute, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof, or Battelle Memorial Institute. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. PACIFIC NORTHWEST NATIONAL LABORATORY operated by BATTELLE for the UNITED STATES DEPARTMENT OF ENERGY under Contract DE-AC06-76RL01830 Printed in the United States of America Available to DOE and DOE contractors from the Office of Scientific and Technical Information, P.O. Box 62, Oak Ridge, TN 37831-0062; ph: (865) 576-8401 fax: (865) 576-5728 email: [email protected] Available to the public from the National Technical Information Service, U.S.
    [Show full text]
  • Vitrification Is a Spontaneous Non-Equilibrium Transition Driven By
    Vitrification is a spontaneous non-equilibrium transition driven by osmotic pressure J. Galen Wang and Roseanna N. Zia∗ Department of Chemical Engineering, Stanford University, Stanford, CA 94305 February 28, 2021 Abstract Persistent dynamics in colloidal glasses suggest the existence of a non-equilibrium driving force for structural relaxation during glassy aging. But the implicit assumption in the literature that colloidal glasses form within the metastable state bypasses the search for a driving force for vit- rification and glassy aging and its connection with a metastable state. The natural relation of osmotic pressure to number-density gradients motivates us to investigate the osmotic pressure as this driving force. We use dynamic simulation to quench a polydipserse hard-sphere colloidal liquid into the putative glass region while monitoring structural relaxation and osmotic pressure. Following quenches to various depths in volume fraction φ (where φRCP ≈ 0:678 for 7% poly- dispersity), the osmotic pressure overshoots its metastable value, then decreases with age toward the metastable pressure, driving redistribution of coordination number and interparticle voids that smooths structural heterogeneity with age. For quenches to 0:56 ≤ φ ≤ 0:58, accessible post-quench volume redistributes with age, allowing the glass to relax into a strong supercooled liquid and easily reach a metastable state. At higher volume fractions, 0:59 ≤ φ < 0:64, this redistribution encounters a barrier that is subsequently overcome by osmotic pressure, allowing the system to relax toward the metastable state. But for φ ≥ 0:64, the overshoot is small com- pared to the high metastable pressure; redistribution of volume stops as particles acquire contacts and get stuck, freezing the system far from the metastable state.
    [Show full text]