Porewater in Compacted Water-Saturated MX-80 Bentonite

2012 ◽  
Vol 1475 ◽  
Author(s):  
Torbjörn Carlsson ◽  
Arto Muurinen ◽  
Michał Matusewicz ◽  
Andrew Root
Keyword(s):  
High Pressure ◽  
Experimental Evidence ◽  
Nuclear Fuel ◽  
Room Temperature ◽  
Spent Nuclear Fuel ◽  
Experimental Results ◽  
Interlayer Water ◽  
Proper Understanding ◽  
Buffer Material ◽  
Water Saturated

ABSTRACTBentonite is planned to be used in many countries as a buffer material in repositories for spent nuclear fuel. The proper understanding and modelling of the functioning of the water-saturated bentonite requires knowledge about the bentonite microstructure and also the way water is distributed between different phases. This paper presents experimental results from our studies of water in compacted, water-saturated MX-80 bentonite at dry densities in the range 0.7-1.6 g/cm3. Three techniques, Cl-porosity, SAXS and proton NMR measurements, were applied to samples kept at room temperature, while TEM imaging was applied to high pressure frozen samples. The combined results of these techniques strongly indicate that the two major water phases in the compacted MX-80 bentonite samples are ‘interlayer’ and ‘non-interlayer’ water. The results of the relative amounts of different water types by SAXS and NMR are very similar. The results by Cl-porosity measurement indicate that only part of the non-interlayer water is available for anions. Those observations are discussed in comparison to TEM micrographs. Our study provides solid experimental evidence for the presence of two major water phases in water-saturated bentonite and estimates their relative proportions and pore sizes.

Photochemische 2+2-Cycloadditionen von Äthylen und Acetylen an 1.3-Cyclohexadien unter erhöhtem Druck / Photochemical 2+2-Cycloadditions of Ethylene and Acetylene to 1,3-Cyclohexadiene under High Pressure

1977 ◽  
Vol 32 (1) ◽  
pp. 47-52 ◽  
Author(s):  
Marlis F. Mirbach ◽  
Manfred J. Mirbach ◽  
Alfons Saus
Keyword(s):  
High Pressure ◽  
Quantum Yield ◽  
Room Temperature ◽  
Kinetic Scheme ◽  
Solvent Mixture ◽  
Experimental Results ◽  
Quantum Yields ◽  
Ethylene Pressure ◽  
Formal Kinetic

The photochemical cycloaddition of 1,3-cyclohexadiene (CHD) to ethylene and acetylene at pressures above 10 bar is described. Upon sensitized irradiation (2-acetylnaphthaline) CHD adds to ethylene at room temperature in dichloromethane to give cis-bicyclo[4,2,0]-oct-2-ene (1) along with dimers of cyclohexadiene. The yield of cross adduct increases with ethylene pressure (10-50 bar) whereas dimerisation decreases. Quantum yields of cross addition and dimerisation at 12 M ethylene were determined to be 0.31 and 0.35 respectively. At a pressure of 15 bar acetylene CHD reacts with acetylene to give bicyclo-[4,2,0]octa-2,7-diene (2) and bicyclo[2,2,2]octa-2,5-diene (3) as the major and minor products respectively. In a solvent mixture containing 60 vol-% CH2Cl2 and 40 vol-% acetone (2) is formed with a quantum yield of φ = 0.2. The experimental results are explained by a formal kinetic scheme.

ROOM TEMPERATURE STABILIZATION OF RADIATION-PRODUCED FREE RADICALS IN BARBITURIC ACIDS

1961 ◽  
Vol 39 (4) ◽  
pp. 514-533 ◽  
Author(s):  
J. A. R. Cloutier
Keyword(s):  
Free Radicals ◽  
Boric Acid ◽  
Experimental Evidence ◽  
Room Temperature ◽  
Barbituric Acid ◽  
Experimental Results ◽  
Temperature Stabilization ◽  
Barbituric Acid Derivatives

Experimental evidence has shown that a boric acid glass may be used to stabilize at room temperature organic free radicals produced by radiation in a number of barbituric acid derivatives. The method and the experimental results are discussed.

scholarly journals Clear evidence against superconductivity in hydrides under high pressure

2021 ◽  
Author(s):  
Jorge Hirsch ◽  
Frank Marsiglio
Keyword(s):  
Magnetic Field ◽  
High Pressure ◽  
High Temperature ◽  
Magnetic Fields ◽  
Experimental Evidence ◽  
High Temperature Superconductors ◽  
Meissner Effect ◽  
Experimental Results ◽  
Definitive Evidence

Abstract The Meissner effect, magnetic field expulsion, is a hallmark of superconductivity. Associated with it, superconductors exclude applied magnetic fields. Recently Minkov et al. presented experimental results reportedly showing ``definitive evidence of the Meissner effect'' in sulfur hydride and lanthanum hydride under high pressure [1]. Instead, we show here that the evidence presented in that paper does not support the case for superconductivity in these materials. Together with experimental evidence discussed in earlier papers, we argue that this clearly indicates that hydrides under pressure are not high temperature superconductors.

Low-temperature and high-pressure phases of a room-temperature ionic liquid and polyiodides: 1-methyl-3-propylimidazolium iodide

2018 ◽  
Vol 206 ◽  
pp. 49-60 ◽  
Author(s):  
Hiroshi Abe ◽  
Hiroaki Kishimura ◽  
Mayumi Takaku ◽  
Mai Watanabe ◽  
Nozomu Hamaya
Keyword(s):  
High Pressure ◽  
Ionic Liquid ◽  
Low Temperature ◽  
Amorphous Phase ◽  
Room Temperature ◽  
Room Temperature Ionic Liquid ◽  
Experimental Results

Experimental results are summarized on the P–T–m diagram. In pure [C3mim][I], amorphous phase appeared both at low-temperature and high-pressure. Stoichiometric [C3mim][I3] promotes crystallization, while non-stoichiometric [C3mim][I3.66] indicates anomalies.

scholarly journals Clear evidence against superconductivity in hydrides under high pressure

2022 ◽  
Author(s):  
J. E. Hirsch ◽  
F. Marsiglio
Keyword(s):  
Magnetic Field ◽  
High Pressure ◽  
High Temperature ◽  
Magnetic Fields ◽  
Experimental Evidence ◽  
High Temperature Superconductors ◽  
Meissner Effect ◽  
Experimental Results ◽  
Definitive Evidence

Abstract The Meissner effect, magnetic field expulsion, is a hallmark of superconductivity. Associated with it, superconductors exclude applied magnetic fields. Recently Minkov et al. presented experimental results reportedly showing “definitive evidence of the Meissner effect” in sulfur hydride and lan-thanum hydride under high pressure1. Instead, we show here that the evidence presented in that paper does not support the case for superconductivity in these materials. Together with experimental evidence discussed in earlier papers, we argue that this clearly indicates that hydrides under pressure are not high temperature superconductors.

scholarly journals Thermophysical, Volumetric, and Excess Properties of Aqueous Solutions of 1-Hexyl-3-methyl Imidazolium Bromide at 298.15 K and 0.1 MPa

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Debasmita Dash ◽  
Shekhar Kumar ◽  
C. Mallika ◽  
U. Kamachi Mudali
Keyword(s):  
Aqueous Solutions ◽  
Nuclear Fuel ◽  
Water Activity ◽  
Room Temperature ◽  
Spent Nuclear Fuel ◽  
Fuel Cycle ◽  
Excess Properties ◽  
Environment Friendly ◽  
Dilute Aqueous Solutions ◽  
Molal Volumes

Room temperature ionic liquids (RTILs) are the environment-friendly alternatives for organic volatile solvents in a host of synthetic, catalytic, and electrochemical applications. These are also being used for various R&D works in nuclear fuel cycle research such as the recovery and purification of nuclides of interest from spent nuclear fuel matrices. In this work, density, refractive index (nD25) at sodium D line, and thermodynamic water activity of the aqueous solution of 1-hexyl-3-methyl imidazolium bromide were determined in dilute aqueous solutions at 298.15 K. These results were used to calculate the apparent molal volumes of each solute over various concentration ranges. The measurements were performed as per ASTM procedures. Vapour pressure was derived using water activity values. Information on excess properties and structural interaction was also reported.

scholarly journals Pulse radiolysis study on the reactivity of NO3˙ radical toward uranous(iv), hydrazinium nitrate and hydroxyl ammonium nitrate at room temperature and at 45 °C

2020 ◽  
Vol 22 (9) ◽  
pp. 5188-5197 ◽  
Author(s):  
R. Musat ◽  
J. L. Marignier ◽  
C. Le Naour ◽  
S. Denisov ◽  
L. Venault ◽  
...  
Keyword(s):  
Nitric Acid ◽  
Ammonium Nitrate ◽  
Nuclear Fuel ◽  
Pulse Radiolysis ◽  
Room Temperature ◽  
Spent Nuclear Fuel ◽  
Acid Solutions ◽  
Nitric Acid Solutions ◽  
No3 Radical

Concentrated nitric acid solutions subjected to radiation produce radicals of extreme importance in the reprocessing of spent nuclear fuel.

High-pressure freezing and freeze substitution of teliospores of the rust fungus Gymnosporangium clavipes

1990 ◽  
Vol 48 (3) ◽  
pp. 692-693
Author(s):  
Robert W. Roberson
Keyword(s):  
High Pressure ◽  
Room Temperature ◽  
Pathogenic Fungus ◽  
Rust Fungus ◽  
Freeze Substitution ◽  
Ice Crystals ◽  
High Pressure Freezing ◽  
Thin Walled Structures ◽  
Cytological Changes ◽  
Dextran Solution

The use of cryo-techniques for the preparation of biological specimens in electron microscopy has led to superior preservation of ultrastructural detail. Although these techniques have obvious advantages, a critical limitation is that only 10-40 μm thick cells and tissue layers can be frozen without the formation of distorting ice crystals. However, thicker samples (600 μm) may be frozen well by rapid freezing under high-pressure (2,100 bar). To date, most work using cryo-techniques on fungi have been confined to examining small, thin-walled structures. High-pressure freezing and freeze substitution are used here to analysis pre-germination stages of specialized, sexual spores (teliospores) of the plant pathogenic fungus Gymnosporangium clavipes C & P.Dormant teliospores were incubated in drops of water at room temperature (25°C) to break dormancy and stimulate germination. Spores were collected at approximately 30 min intervals after hydration so that early cytological changes associated with spore germination could be monitored. Prior to high-pressure freezing, the samples were incubated for 5-10 min in a 20% dextran solution for added cryoprotection during freezing. Forty to 50 spores were placed in specimen cups and holders and immediately frozen at high pressure using the Balzers HPM 010 apparatus.

Convective processes in spent nuclear fuel canisters

2002 ◽  
Author(s):  
Glenn E. McCreery ◽  
Keith G. Condie ◽  
Randy C. Clarksean ◽  
Donald M. McEligot
Keyword(s):  
Nuclear Fuel ◽  
Spent Nuclear Fuel ◽  
Convective Processes ◽  
Nuclear Fuel Canisters
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