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Sample records for cesium hydrides

  1. Interstellar Hydrides

    CERN Document Server

    Gerin, Maryvonne; Goicoechea, Javier R

    2016-01-01

    Interstellar hydrides -- that is, molecules containing a single heavy element atom with one or more hydrogen atoms -- were among the first molecules detected outside the solar system. They lie at the root of interstellar chemistry, being among the first species to form in initially-atomic gas, along with molecular hydrogen and its associated ions. Because the chemical pathways leading to the formation of interstellar hydrides are relatively simple, the analysis of the observed abundances is relatively straightforward and provides key information about the environments where hydrides are found. Recent years have seen rapid progress in our understanding of interstellar hydrides, thanks largely to far-IR and submillimeter observations performed with the Herschel Space Observatory. In this review, we will discuss observations of interstellar hydrides, along with the advanced modeling approaches that have been used to interpret them, and the unique information that has thereby been obtained.

  2. Cesium-137

    International Nuclear Information System (INIS)

    This sheet belongs to a collection which relates to the use of radionuclides essentially in unsealed sources. Its goal is to gather on a single document the most relevant information as well as the best prevention practices to be implemented. These sheets are made for the persons in charge of radiation protection: users, radioprotection-skill persons, labor physicians. Each sheet treats of: 1 - the radio-physical and biological properties; 2 - the main uses; 3 - the dosimetric parameters; 4 - the measurement; 5 - the protection means; 6 - the areas delimitation and monitoring; 7 - the personnel classification, training and monitoring; 8 - the effluents and wastes; 9 - the authorization and declaration administrative procedures; 10 - the transport; and 11 - the right conduct to adopt in case of incident or accident. This sheet deals specifically with Cesium-137

  3. Hydride compressor

    Science.gov (United States)

    Powell, James R.; Salzano, Francis J.

    1978-01-01

    Method of producing high energy pressurized gas working fluid power from a low energy, low temperature heat source, wherein the compression energy is gained by using the low energy heat source to desorb hydrogen gas from a metal hydride bed and the desorbed hydrogen for producing power is recycled to the bed, where it is re-adsorbed, with the recycling being powered by the low energy heat source. In one embodiment, the adsorption-desorption cycle provides a chemical compressor that is powered by the low energy heat source, and the compressor is connected to a regenerative gas turbine having a high energy, high temperature heat source with the recycling being powered by the low energy heat source.

  4. Synthesis of ruthenium hydride

    Science.gov (United States)

    Kuzovnikov, M. A.; Tkacz, M.

    2016-02-01

    Ruthenium hydride was synthesized at a hydrogen pressure of about 14 GPa in a diamond-anvil cell. Energy-dispersive x-ray diffraction was used to monitor the ruthenium crystal structure as a function of hydrogen pressure up to 30 GPa. The hydride formation was accompanied by phase transition from the original hcp structure of the pristine metal to the fcc structure. Our results confirmed the theoretical prediction of ruthenium hydride formation under hydrogen pressure. The standard Gibbs free energy of the ruthenium hydride formation reaction was calculated assuming the pressure of decomposition as the equilibrium pressure.

  5. Cesium chemistry in irradiated fuel; cesium uranates

    International Nuclear Information System (INIS)

    The physico-chemical behaviour of fission products in nuclear fuel during and after irradiation has been studied extensively during the past decades. In spite of the large amount of chemical, crystallographic and thermodynamic data available, the knowledge on the very complicated UO2-fission product system is still far from complete. The paper discusses the multi variant character of uranium in cesium uranates, which has been assessed by a systematic X-ray Photoelectron Spectroscopy (XPS) study of a series of cesium uranates

  6. Hydrolysis of lithium hydride

    International Nuclear Information System (INIS)

    Due to its high hydrogen density and unique nuclear chemistry, lithium hydride, in all its isotopic forms, has an unsurpassed place in modem nuclear weapons. The hydrolysis of the material, and the outgassing of hydrogen from the bulk, are crucial to the performance of the material in service. This thesis describes research conducted at AWE Aldermaston, UK, to examine the hydrolysis and hydrogen outgassing from the bulk material, with the aim of ultimately developing the kinetics 8c mechanisms responsible. The basic chemistry is of great interest, especially the reaction with water. This reaction, whilst being fairly extensively studied in the past, has not been conclusively described with an accepted mechanism and associated kinetics. The last significant UK work on the topic was by Imperial College, London, under contract to AW(R)E in the late 1960s. This thesis describes the development of: (i) a solid state NMR spectroscopy technique to examine semi-quantitatively the surface of bulk lithium hydride for its chemical composition, and (ii) a dedicated lithium hydride inert atmosphere gravimetric analysis glove box to study the hydride/water reaction. Solid State NMR Spectroscopy has been utilised for the first time to probe the hydride/hydroxide ratio of partially hydrolysed lithium hydride. 6Li chemical shifts have been established for species of interest and extremely long, up to 17 hours, T1 relaxation times have been measured for 6Li hydride and hydroxide. A method for semi-quantitatively determining the hydroxide/hydride composition of a partially reacted sample has been developed, based on a 'dual-scan' technique using one short and one long pulse sequence. Gravimetric analysis has been developed for lithium hydride/humidity studies. This facility fully contains gravimetric analysis within an argon glove box, with the ability to control the sample atmosphere from room temperature to 60 deg C and from 0.5 to 40 percent relative humidity. The hydrolysis of

  7. Lightweight hydride storage materials

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, G.J.; Guthrie, S.E.; Bauer, W. [Sandia National Labs., Livermore, CA (United States)

    1995-09-01

    The need for lightweight hydrides in vehicular applications has prompted considerable research into the use of magnesium and its alloys. Although this earlier work has provided some improved performance in operating temperature and pressure, substantial improvements are needed before these materials will significantly enhance the performance of an engineered system on a vehicle. We are extending the work of previous investigators on Mg alloys to reduce the operating temperature and hydride heat of formation in light weight materials. Two important results will be discussed in this paper: (1) a promising new alloy hydride was found which has better pressure-temperature characteristics than any previous Mg alloy and, (2) a new fabrication process for existing Mg alloys was developed and demonstrated. The new alloy hydride is composed of magnesium, aluminum and nickel. It has an equilibrium hydrogen overpressure of 1.3 atm. at 200{degrees}C and a storage capacity between 3 and 4 wt.% hydrogen. A hydrogen release rate of approximately 5 x 10{sup -4} moles-H{sub 2}/gm-min was measured at 200{degrees}C. The hydride heat of formation was found to be 13.5 - 14 kcal/mole-H{sub 2}, somewhat lower than Mg{sub 2}Ni. The new fabrication method takes advantage of the high vapor transport of magnesium. It was found that Mg{sub 2}Ni produced by our low temperature process was better than conventional materials because it was single phase (no Mg phase) and could be fabricated with very small particle sizes. Hydride measurements on this material showed faster kinetic response than conventional material. The technique could potentially be applied to in-situ hydride bed fabrication with improved packing density, release kinetics, thermal properties and mechanical stability.

  8. Conference 'Chemistry of hydrides' Proceedings

    International Nuclear Information System (INIS)

    This collection of thesis of conference of Chemistry hydrides presents the results of investigations concerning of base questions of chemistry of nonorganic hydrides, including synthesis questions, studying of physical and chemical properties, thermodynamics, analytical chemistry, investigation of structure, equilibriums in the systems of metal-hydrogen, behaviour of nonorganic hydrides in non-water mediums and applying investigations in the chemistry area and technology of nonorganic hydrides

  9. Decorporation of cesium-137

    International Nuclear Information System (INIS)

    Cesium radio-isotopes, especially cesium-137 (137Cs) are among the radionuclides of main importance produced by a fission reaction in reactor or a nuclear weapon explosion. In the environment, 137Cs is a major contaminant which can cause severe β, γirradiations and contaminations. 137Cs is distributed widely and relatively uniformly throughout the body with the highest concentration in skeletal muscles. A treatment becomes difficult afterwards. The purposes of this report are Firstly to compare the Prussian blue verses cobalt and potassium ferrocyanide (D.I. blue) efficiency for the 137Cs decorporation and secondly to assess a chronological treatment with D.I. blue. (author)

  10. Analysis of radioactive cesium

    International Nuclear Information System (INIS)

    The procedure of analysis of cesium-137 in environmental samples is described. The standard measurement of cesium-137 is made by using a standard solution and a low background G-M counter system. Precipitation and dust are collected on a stainless steel pan. The collected samples are treated by evaporation and extraction or ion exchange and adsorption method. The sample is then quantitatively analyzed. The measurement of cesium-137 is made according to the standard of measurement. Samples collected from inland water and sea water are also treated by evaporation or ion exchange method. The measurements of cesium-137 are also made. This manual describes how to collect soil samples. The collected soil is dried and treated to make samples for activity measurement. Activity measurement is made according to the standard of measurement, then the data are analyzed. Samples are also collected from sediment of sea bottom or river bottom, agricultural products, milk, marine organisms, and daily foods. This manual describes on the methods to collect samples and the treatment to make samples for measurement. (Kato, T.)

  11. Metal hydride actuation device

    International Nuclear Information System (INIS)

    A self-recocking actuation device is disclosed. One possible use for it is in conjunction with a pneumatic fire protection system. This invention employs the process known as occlusion to store large amounts of gas in a small volume. Metal hydrides in a chamber are used to store hydrogen in the disclosed preferred embodiment. Upon the application of heat-from a heat source like a resistance heater-the charged metal hydride releases its hydrogen (H2) in a chamber having only one exit opening which empties into a sealed bellows. This bellows contacts a piston located in another chamber wherein a biased resetting spring is provided to normally maintain the piston in contact with the bellows. As the pressure from the H2 gas builds up, it overcomes the biased spring to move it and the piston along with an associated pin or other actuator. If used to actuate a pneumatic fire protection system, the pin or actuator at the downward side of its stroke in turn, may puncture a shearable diaphragm or in some other way releases the contents of a container containing a second gas, like nitrogen (N2), which is then released from a second exit port in a different chamber to charge the fire protection system. Recocking of the piston begins as the heating of the metal hydride ceases. As cooling takes place the hydrogen is absorbed to reenter the hydride to decrease the gas pressure supplied. The piston's biased resetting spring then recocks the piston to its original position

  12. Air and metal hydride battery

    Energy Technology Data Exchange (ETDEWEB)

    Lampinen, M.; Noponen, T. [Helsinki Univ. of Technology, Otaniemi (Finland). Lab. of Applied Thermodynamics

    1998-12-31

    The main goal of the air and metal hydride battery project was to enhance the performance and manufacturing technology of both electrodes to such a degree that an air-metal hydride battery could become a commercially and technically competitive power source for electric vehicles. By the end of the project it was possible to demonstrate the very first prototype of the air-metal hydride battery at EV scale, achieving all the required design parameters. (orig.)

  13. Materials engineering of metal hydrides

    International Nuclear Information System (INIS)

    Intermetallic hydrides of the AB5 type have enthalpies in the range valid for chemical heat pumps. A scheme for manufacturing hydrides with optimal properties for a chemical heat pump is described, using LaNi/sub 5-x/Al/sub x/ and ZrV/sub 2x/Cr/sub x as examples. The Laves-phase ternary hydrides appear to be good candidates for gettering hydrogen in the Tokamak Fusion Test Reactor

  14. Cesium reservoir and interconnective components

    International Nuclear Information System (INIS)

    The program objective is to demonstrate the technology readiness of a TFE (thermionic fuel element) suitable for use as the basic element in a thermionic reactor with electric power output in the 0.5 to 5.0 MW range. A thermionic converter must be supplied with cesium vapor for two reasons. Cesium atoms adsorbed on the surface of the emitter cause a reduction of the emitter work function to permit high current densities without excessive heating of the emitter. The second purpose of the cesium vapor is to provide space-charge neutralization in the emitter-collector gap so that the high current densities may flow across the gap unattenuated. The function of the cesium reservoir is to provide a source of cesium atoms, and to provide a reserve in the event that cesium is lost from the plasma by any mechanism. This can be done with a liquid cesium metal reservoir in which case it is heated to the desired temperature with auxiliary heaters. In a TFE, however, it is desirable to have the reservoir passively heated by the nuclear fuel. In this case, the reservoir must operate at a temperature intermediate between the emitter and the collector, ruling out the use of liquid reservoirs. Integral reservoirs contained within the TFE will produce cesium vapor pressures in the desired range at typical electrode temperatures. The reservoir material that appears to be the best able to meet requirements is graphite. Cesium intercalates easily into graphite, and the cesium pressure is insensitive to loading for a given intercalation stage. The goals of the cesium reservoir test program were to verify the performance of Cs-graphite reservoirs in the temperature-pressure range of interest to TFE operation, and to test the operation of these reservoirs after exposure to a fast neutron fluence corresponding to seven year mission lifetime. In addition, other materials were evaluated for possible use in the integral reservoir

  15. Cesium-137 in biosphere

    International Nuclear Information System (INIS)

    The behaviour of cesium-137 in environment is reviewed. Problems on 137Cs migration in environment, on metabolism andbiological effects are considered. Data on nuclide accumulation in various plants, ways of their entering the man's organism are presented. It is marked that the rate of 137Cs metabolism in the man's organism depends considerably on age, sex, temperature of environment, conditions for activity, water and mineral metabolism and some other factors. It is shown that the annual effective equivalent dose per capita will increase to 2000 yr. up to 1 μSv, that constitutes 0.05% of the average value of irradiation by a natural source

  16. Effects of microwave irradiation on metal hydrides and complex hydrides

    International Nuclear Information System (INIS)

    Effects of single-mode microwave irradiation on metal hydrides, MHn (LiH, MgH2, CaH2, TiH2, VH0.81, ZrH2, and LaH2.48) and complex hydrides MBH4 (LiBH4, NaBH4, and KBH4) were systematically investigated. Among the metal hydrides, TiH2, VH0.81, ZrH2, and LaH2.48 exhibit a rapid heating by microwave irradiation, where small amount of hydrogen (less than 0.5 mass%) are desorbed. On the other hand, LiBH4 is heated above 380 K by microwave irradiation, where 13.7 mass% of hydrogen is desorbed. The rapid heating of metal hydrides such as TiH2, VH0.81, ZrH2, and LaH2.48 are mainly due to the conductive loss. Meanwhile the microwave heating in LiBH4 is attributed to the conductive loss which is caused by a structural transition. The difference in the amount of desorbed hydrogen between metal hydrides and complex hydrides might be caused by the different microwave penetration depth and/or the temperature saturation in the microwave irradiation process. Microwave heating might be applied to hydrogen storage system, though further development of hydrides themselves and engineering techniques are required

  17. Preparation of metallic terbium and terbium hydride

    International Nuclear Information System (INIS)

    A method of metallic terbium preparation is described. The method consists in vacuum thermolysis of terbium hydride prepared as a result of terbium chloride interaction with lithium hydride. The prepared modification of terbium hydride demonstrates a high stability in the air. It is pointed out that problems arising from direct hydridation of the metal are responsible for certain advantages of the terbium hydride preparation method described

  18. Erbium hydride decomposition kinetics.

    Energy Technology Data Exchange (ETDEWEB)

    Ferrizz, Robert Matthew

    2006-11-01

    Thermal desorption spectroscopy (TDS) is used to study the decomposition kinetics of erbium hydride thin films. The TDS results presented in this report are analyzed quantitatively using Redhead's method to yield kinetic parameters (E{sub A} {approx} 54.2 kcal/mol), which are then utilized to predict hydrogen outgassing in vacuum for a variety of thermal treatments. Interestingly, it was found that the activation energy for desorption can vary by more than 7 kcal/mol (0.30 eV) for seemingly similar samples. In addition, small amounts of less-stable hydrogen were observed for all erbium dihydride films. A detailed explanation of several approaches for analyzing thermal desorption spectra to obtain kinetic information is included as an appendix.

  19. Metal hydride air conditioner

    Institute of Scientific and Technical Information of China (English)

    YANG; Ke; DU; Ping; LU; Man-qi

    2005-01-01

    The relationship among the hydrogen storage properties, cycling characteristics and thermal parameters of the metal hydride air conditioning systems was investigated. Based on a new alloy selection model, three pairs of hydrogen storage alloys, LaNi4.4 Mn0.26 Al0.34 / La0.6 Nd0.4 Ni4.8 Mn0.2 Cu0. 1, LaNi4.61Mn0. 26 Al0.13/La0.6 Nd0.4 Ni4.8 Mn0.2 Cu0. 1 and LaNi4.61 Mn0.26 Al0.13/La0.6 Y0.4 Ni4.8 Mn0. 2, were selected as the working materials for the metal hydride air conditioning system. Studies on the factors affecting the COP of the system showed that higher COP and available hydrogen content need the proper operating temperature and cycling time,large hydrogen storage capacity, flat plateau and small hysterisis of hydrogen alloys, proper original input hydrogen content and mass ratio of the pair of alloys. It also needs small conditioning system was established by using LaNi4.61 Mn0.26 Al0. 13/La0.6 Y0.4 Ni4.8 Mn0.2 alloys as the working materials, which showed that under the operating temperature of 180℃/40℃, a low temperature of 13℃ was reached, with COP =0.38 and Wnet =0.09 kW/kg.

  20. Hydride development for hydrogen storage

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, G.J.; Guthrie, S.E.; Bauer, W.; Yang, N.Y.C. [Sandia National Lab., Livermore, CA (United States); Sandrock, G. [SunaTech, Inc., Ringwood, NJ (United States)

    1996-10-01

    The purpose of this project is to develop and demonstrate improved hydride materials for hydrogen storage. The work currently is organized into four tasks: hydride development, bed fabrication, materials support for engineering systems, and IEA Annex 12 activities. At the present time, hydride development is focused on Mg alloys. These materials generally have higher weight densities for storing hydrogen than rare earth or transition metal alloys, but suffer from high operating temperatures, slow kinetic behavior and material stability. The authors approach is to study bulk alloy additions which increase equilibrium overpressure, in combination with stable surface alloy modification and particle size control to improve kinetic properties. This work attempts to build on the considerable previous research in this area, but examines specific alloy systems in greater detail, with attention to known phase properties and structures. The authors have found that specific phases can be produced which have significantly improved hydride properties compared to previous studies.

  1. Complex Hydrides for Hydrogen Storage

    Energy Technology Data Exchange (ETDEWEB)

    Slattery, Darlene; Hampton, Michael

    2003-03-10

    This report describes research into the use of complex hydrides for hydrogen storage. The synthesis of a number of alanates, (AIH4) compounds, was investigated. Both wet chemical and mechano-chemical methods were studied.

  2. Low density metal hydride foams

    International Nuclear Information System (INIS)

    Disclosed is a low density foam having a porosity of from 0 to 98% and a density less than about 0.67 gm/cc, prepared by heating a mixture of powered lithium hydride and beryllium hydride in an inert atmosphere at a temperature ranging from about 455 to about 490 K for a period of time sufficient to cause foaming of said mixture, and cooling the foam thus produced. Also disclosed is the process of making the foam. 6 figures

  3. Geoneutrino and Hydridic Earth model

    CERN Document Server

    Bezrukov, Leonid

    2013-01-01

    Uranium, Thorium and Potassium-40 abundances in the Earth were calculated in the frame of Hydridic Earth model. Terrestrial heat producton from U, Th and K40 decays was calculated also. We must admit the existance of Earth expansion process to understand the obtained large value of terrestrial heat producton. The geoneutrino detector with volume more than 5 kT (LENA type) must be constructed to definitely separate between Bulk Silicat Earth model and Hydridic Earth model.

  4. Mechanical properties and fracture of titanium hydrides

    International Nuclear Information System (INIS)

    Titanium hydrides tend to suffer fracture when their thicknesses reach a critical thickness. Morphology and mechanical property of the hydrides are, however, not well known. The study aims to reveal the hydride morphology and fracture types of the hydrides. Chevron shaped plate hydrides were found to be produced on the surface of pure titanium (Grade 1) and Grade 7 titanium absorbing hydrogen. There were tree types of fracture of the hydrides, i.e., crack in hydride layer, exfoliation of the layer and shear-type fracture of the hydride plates, during the growth of the hydrides and deformation. We next estimated the true stress-strain curves of the hydrides on Grade 1 and 7 titanium using the dual Vickers indentation method, and the critical strain causing the Mode-I fine crack by indentation. Fracture strength and strain of the hydrides in Grade 1 titanium were estimated as 566 MPa and 4.5%, respectively. Those of the hydride in Grade 7 titanium were 498 MPa and 16%. Though the fracture strains estimated from the plastic instability of true stress-strain curves were approximately the half of those estimated by finite element method, the titanium hydrides were estimated to possess some extent of toughness or plastic deformation capability. (author)

  5. Cesium Concentration in MCU Solvent

    International Nuclear Information System (INIS)

    During Modular Caustic-Side Solvent Extraction (CSSX) Unit (MCU) operations, Cs-137 concentrations in product streams will vary depending on the location in the process and on the recent process conditions. Calculations of cesium concentrations under a variety of operating conditions reveal the following: (1) Under nominal operations with salt solution feed containing 1.1 Ci Cs-137 per gallon, the maximum Cs-137 concentration in the process will occur in the strip effluent (SE) and equal 15-16.5 Ci/gal. (2) Under these conditions, the majority of the solvent will contain 0.005 to 0.01 Ci/gal, with a limited portion of the solvent in the contactor stages containing ∼4 Ci/gal. (3) When operating conditions yield product near 0.1 Ci Cs-137/gal in the decontaminated salt solution (DSS), the SE cesium concentration will be the same or lower than in nominal operations, but majority of the stripped solvent will increase to ∼2-3 Ci/gal. (4) Deviations in strip and waste stream flow rates cause the largest variations in cesium content: (a) If strip flow rates deviate by -30% of nominal, the SE will contain ∼23 Ci/gal, although the cesium content of the solvent will increase to only 0.03 Ci/gal; (b) If strip flow rate deviates by -77% (i.e., 23% of nominal), the SE will contain 54 Ci/gal and solvent will contain 1.65 Ci/gal. At this point, the product DSS will just reach the limit of 0.1 Ci/gal, causing the DSS gamma monitors to alarm; and (c) Moderate (+10 to +30%) deviations in waste flow rate cause approximately proportional increases in the SE and solvent cesium concentrations. Recovery from a process failure due to poor cesium stripping can achieve any low cesium concentration required. Passing the solvent back through the contactors while recycling DSS product will produce a ∼70% reduction during one pass through the contactors (assuming the stripping D value is no worse than 0.36). If the solvent is returned to the solvent hold tank (containing additional

  6. Hydrogen storage in magnesium-based hydrides and hydride composites

    International Nuclear Information System (INIS)

    Mg and Mg-based hydrides have attracted much attention because of their high gravimetric hydrogen storage densities and favourable kinetic properties. Due to novel preparation methods and the development of suitable catalysts, hydrogen uptake and desorption is now possible within less than 2 min. However, the hydrogen reaction enthalpy of pure Mg is too high for many applications, for example, for the zero emission car. Therefore, different routes are explored to tailor the hydrogen reaction enthalpy to potential applications. This article summarizes the recent developments concerning sorption properties and thermodynamics of Mg-based hydrides for hydrogen storage applications. In particular, promising strategies to decrease the hydrogen reaction enthalpy by alloying and the use of reactive hydride composites are discussed

  7. A New Reducing Regent: Dichloroindium Hydride

    Institute of Scientific and Technical Information of China (English)

    A. BABA; I. SHIBATA; N. HAYASHI

    2005-01-01

    @@ 1Introduction Among the hydride derivatives of group 13 elements, various types of aluminum hydrides and boron hydrides have been employed as powerful reduction tools. Indium hydrides have not received much attention,whereas the synthesis of indium trihydride (InH3) was reported several decades ago[1]. There have been no precedents for monometallic indium hydrides having practical reactivity, while activated hydrides such as an ate complex LiPhn InH4-n (n = 0- 2) and phosphine-coordinated indium hydrides readily reduce carbonyl compounds. In view of this background, we focused on the development of dichloroindium hydrides (Cl2InH) as novel reducing agents that bear characteristic features in both ionic and radical reactions.

  8. Luminescent properties of aluminum hydride

    International Nuclear Information System (INIS)

    We studied cathodoluminescence and photoluminescence of α-AlH3– a likely candidate for use as possible hydrogen carrier in hydrogen-fueled vehicles. Luminescence properties of original α-AlH3 and α-AlH3 irradiated with ultraviolet were compared. The latter procedure leads to activation of thermal decomposition of α-AlH3 and thus has a practical implementation. We showed that the original and UV-modified aluminum hydride contain luminescence centers ‐ structural defects of the same type, presumably hydrogen vacancies, characterized by a single set of characteristic bands of radiation. The observed luminescence is the result of radiative intracenter relaxation of the luminescence center (hydrogen vacancy) excited by electrons or photons, and its intensity is defined by the concentration of vacancies, and the area of their possible excitation. UV-activation of the dehydrogenation process of aluminum hydride leads to changes in the spatial distribution of the luminescence centers. For short times of exposure their concentration increases mainly in the surface regions of the crystals. At high exposures, this process extends to the bulk of the aluminum hydride and ends with a decrease in concentration of luminescence centers in the surface region. - Highlights: • Aluminum hydride contains hydrogen vacancies which serve as luminescence centers. • The luminescence is the result of radiative relaxation of excited centers. • Hydride UV-irradiation alters distribution and concentration of luminescence centers

  9. Luminescent properties of aluminum hydride

    Energy Technology Data Exchange (ETDEWEB)

    Baraban, A.P.; Gabis, I.E.; Dmitriev, V.A. [Saint-Petersburg State University, Department of Physics, Saint-Petersburg 198504 (Russian Federation); Dobrotvorskii, M.A., E-mail: mstislavd@gmail.com [Saint-Petersburg State University, Department of Physics, Saint-Petersburg 198504 (Russian Federation); Kuznetsov, V.G. [Saint-Petersburg State University, Department of Physics, Saint-Petersburg 198504 (Russian Federation); Matveeva, O.P. [National Mineral Resources University, Saint Petersburg 199106 (Russian Federation); Titov, S.A. [Petersburg State University of Railway Transport, Saint-Petersburg 190031 (Russian Federation); Voyt, A.P.; Elets, D.I. [Saint-Petersburg State University, Department of Physics, Saint-Petersburg 198504 (Russian Federation)

    2015-10-15

    We studied cathodoluminescence and photoluminescence of α-AlH{sub 3}– a likely candidate for use as possible hydrogen carrier in hydrogen-fueled vehicles. Luminescence properties of original α-AlH{sub 3} and α-AlH{sub 3} irradiated with ultraviolet were compared. The latter procedure leads to activation of thermal decomposition of α-AlH{sub 3} and thus has a practical implementation. We showed that the original and UV-modified aluminum hydride contain luminescence centers ‐ structural defects of the same type, presumably hydrogen vacancies, characterized by a single set of characteristic bands of radiation. The observed luminescence is the result of radiative intracenter relaxation of the luminescence center (hydrogen vacancy) excited by electrons or photons, and its intensity is defined by the concentration of vacancies, and the area of their possible excitation. UV-activation of the dehydrogenation process of aluminum hydride leads to changes in the spatial distribution of the luminescence centers. For short times of exposure their concentration increases mainly in the surface regions of the crystals. At high exposures, this process extends to the bulk of the aluminum hydride and ends with a decrease in concentration of luminescence centers in the surface region. - Highlights: • Aluminum hydride contains hydrogen vacancies which serve as luminescence centers. • The luminescence is the result of radiative relaxation of excited centers. • Hydride UV-irradiation alters distribution and concentration of luminescence centers.

  10. Cesium in the nutrient cycle

    International Nuclear Information System (INIS)

    Most radioactive cesium in forests is deposited in soil, from which it passes into berries and mushrooms, and further to game. The cesium contents of Finnish berries and mushrooms vary depending on the intensity of Chernobyl fallout. Northern Haeme, Pirkanmaa and parts of central Finland received the most fallout. Weather conditions and the environmental factors, and other circumstances during the growth period, also affect the contents. However, consumption of wild berries, mushrooms and game need not be restricted because of radioactivity anywhere in Finland

  11. Cesium contamination of heather honey

    International Nuclear Information System (INIS)

    In heather honey from Lueneburger Heide, FRG, relatively high values of cesium activity were found (up to about 650 Bq/kg). Activity values for heather honey, Calluna vulgaris plants and soil were measured. It is assumed that the origin of this activity is the direct Chernobyl fallout. There may also be a high transfer of cesium from the soil to the Calluna vulgaris plant, but in order to determine the transfer factor, fresh plants are needed, which have grown later than in spring 1986. (author) 21 refs.; 2 figs.; 2 tabs

  12. Hydrogen, lithium, and lithium hydride production

    Science.gov (United States)

    Brown, Sam W; Spencer, Larry S; Phillips, Michael R; Powell, G. Louis; Campbell, Peggy J

    2014-03-25

    A method of producing high purity lithium metal is provided, where gaseous-phase lithium metal is extracted from lithium hydride and condensed to form solid high purity lithium metal. The high purity lithium metal may be hydrided to provide high purity lithium hydride.

  13. Thermomechanical properties of hafnium hydride

    International Nuclear Information System (INIS)

    Fine bulk samples of delta-phase Hf hydride with various hydrogen contents (CH) ranging from 1.62 to 1.72 in the atomic ratio (H/Hf) were prepared, and their thermomechanical properties were characterized. At room temperature, the sound velocity and Vickers hardness were measured. The elastic modulus was calculated from the measured sound velocity. In the temperature range from room temperature to 673 K, the thermal expansion was measured by using a dilatometer, and the linear thermal expansion coefficient was calculated. Empirical equations describing the thermomechanical properties of Hf hydride as a function of CH were proposed. (author)

  14. Cesium transport data for HTGR systems

    International Nuclear Information System (INIS)

    Cesium transport data on the release of cesium from HTGR fuel elements are reviewed and discussed. The data available through 1976 are treated. Equations, parameters, and associated variances describing the data are presented. The equations and parameters are in forms suitable for use in computer codes used to calculate the release of metallic fission products from HTGR fuel elements into the primary circuit. The data cover the following processes: (1) diffusion of cesium in fuel kernels and pyrocarbon, (2) sorption of cesium on fuel rod matrix material and on graphite, and (3) migration of cesium in graphite. The data are being confirmed and extended through work in progress

  15. Cesium (Cs) particle formation based on a laser photochemical reaction with a self-injection-seeded Ti:sapphire laser for Cs isotope separation

    International Nuclear Information System (INIS)

    We studied laser isotope separation of cesium (Cs) on the basis of a laser photochemical reaction and two-photon excitation scheme using a narrow line width Ti:sapphire laser to reduce long-term radioactive toxicity of a long-lived fission product. Using resonant laser irradiation to Cs atoms in hydrogen gas, we observed cesium hydride fine particles and confirmed the formation by calculations using rate equations. Our results show that the process seems promising for efficient Cs isotope separation. (author)

  16. Properties of nanoscale metal hydrides

    International Nuclear Information System (INIS)

    Nanoscale hydride particles may exhibit chemical stabilities which differ from those of a macroscopic system. The stabilities are mainly influenced by a surface energy term which contains size-dependent values of the surface tension, the molar volume and an additional term which takes into account a potential reduction of the excess surface energy. Thus, the equilibrium of a nanoparticular hydride system may be shifted to the hydrogenated or to the dehydrogenated side, depending on the size and on the prefix of the surface energy term of the hydrogenated and dehydrogenated material. Additional complexity appears when solid-state reactions of complex hydrides are considered and phase segregation has to be taken into account. In such a case the reversibility of complex hydrides may be reduced if the nanoparticles are free standing on a surface. However, it may be enhanced if the system is enclosed by a nanoscale void which prevents the reaction partners on the dehydrogenated side from diffusing away from each other. Moreover, the generally enhanced diffusivity in nanocrystalline systems may lower the kinetic barriers for the material's transformation and, thus, facilitate hydrogen absorption and desorption.

  17. Decorporation of cesium-137; Decorporation du cesium-137

    Energy Technology Data Exchange (ETDEWEB)

    Le Fleche, Ph.; Destombe, C.; Grasseau, A.; Mathieu, J.; Chancerelle, Y.; Mestries, J.C. [GMR, Direction des Recherches, Etudes et Techniques, 94 - Arcueil (France)

    1997-12-31

    Cesium radio-isotopes, especially cesium-137 ({sup 137}Cs) are among the radionuclides of main importance produced by a fission reaction in reactor or a nuclear weapon explosion. In the environment, {sup 137}Cs is a major contaminant which can cause severe {beta}, {gamma}irradiations and contaminations. {sup 137}Cs is distributed widely and relatively uniformly throughout the body with the highest concentration in skeletal muscles. A treatment becomes difficult afterwards. The purposes of this report are Firstly to compare the Prussian blue verses cobalt and potassium ferrocyanide (D.I. blue) efficiency for the {sup 137}Cs decorporation and secondly to assess a chronological treatment with D.I. blue. (author)

  18. Deformation of vanadium and niobium on hydridation

    International Nuclear Information System (INIS)

    Deformation of wire samples made of polycrystalline vanadium and niobium on hydridation is studied. It is shown that sample allowance under loading after deformation below the yield strength doesn't cause considerable creep. Cathode saturation of samples with hydrogen sharply accelerates vanadium microdeformation velocity, that is connected with the beginning of intensive vanadium hydride precipitation (β-phase) from α-solid vanadium-hydrogen solution. Niobium hydridation at the first stage doesn't hydridation at the first stage doesn't cause negative deformation, then change in deformation direction takes place at the moment of intensive growth of the hydride phase. The conclusion is made that in both metals microdeformation is determined by contribution of two components: deformation caused by changing a shift module of metal-hydrogen system, and deformation caused by the oriented growth of the hydride phase in the field of apphed stresses

  19. Anodematerials for Metal Hydride Batteries

    DEFF Research Database (Denmark)

    Jensen, Jens Oluf

    1997-01-01

    This report describes the work on development of hydride forming alloys for use as electrode materials in metal hydride batteries. The work has primarily been concentrated on calcium based alloys derived from the compound CaNi5. This compound has a higher capacity compared with alloys used in today...... was developed. The parameters milling time, milling intensity, number of balls and form of the alloying metals were investigated. Based on this a final alloying technique for the subsequent preparation of electrode materials was established. The technique comprises milling for 4 hours twice possibly...... followed by annealing at 700°C for 12 hours. The alloys appeared to be nanocrystalline with an average crystallite size around 10 nm before annealing. Special steel containers was developed for the annealing of the metal powders in inert atmosphere. The use of various annealing temperatures was...

  20. Tritium processing using metal hydrides

    International Nuclear Information System (INIS)

    E.I. duPont de Nemours and Company is commissioned by the US Department of Energy to operate the Savannah River Plant and Laboratory. The primary purpose of the plant is to produce radioactive materials for national defense. In keeping with current technology, new processes for the production of tritium are being developed. Three main objectives of this new technology are to ease the processing of, ease the storage of, and to reduce the operating costs of the tritium production facility. Research has indicated that the use of metal hydrides offers a viable solution towards satisfying these objectives. The Hydrogen and Fuels Technology Division has the responsibility to conduct research in support of the tritium production process. Metal hydride technology and its use in the storage and transportation of hydrogen will be reviewed

  1. Extraction of radioactive cesium from tea leaves

    International Nuclear Information System (INIS)

    Radioactive contamination of foodstuffs attributed to the Fukushima Daiichi nuclear disaster has become a social problem. This study investigated the extraction of radioactive cesium from the contaminated leaves to the tea. The green tea was brewed twice reusing the same leaves to study the difference in extraction of cesium between the first and second brew. Moreover, the extraction of cesium was studied in correlation to brewing time. The concentration of radioactive cesium was determined with gamma spectrometry, and the concentration of caffeine was determined with absorption spectrometry. About 40% of cesium was extracted from leaves in the first brew, and about 80% was extracted in the second brew. The extraction of cesium increased over time, and it reached about 80% after 10 minutes brew. The ratio of radioactive cesium to caffeine decreased linearly over time. This study revealed that the extraction of cesium was higher for the second brew, and a rapid increase in extraction was seen as the tea was brewed for 6 minutes and more. Therefore, the first brew of green tea, which was brewed within 5 minutes, contained the least extraction of radioactive cesium from the contaminated leaves. (author)

  2. Drying dichloromethane over calcium hydride

    OpenAIRE

    sprotocols

    2015-01-01

    Authors: Lucas Kinard, Kurtis Kasper & Antonios Mikos ### Abstract This protocol describes the drying of dichloromethane by a simple 10 step procedure. One can implement this protocol using common lab glass and lab equipment. First, dichloromethane is refluxed with calcium hydride to remove water. Then, dichloromethane is distilled to separate it from the byproducts of the reflux reaction. This procedure can be implemented in 1 day. ### Introduction In many instances i...

  3. Complex hydrides for hydrogen storage

    Science.gov (United States)

    Zidan, Ragaiy

    2006-08-22

    A hydrogen storage material and process of forming the material is provided in which complex hydrides are combined under conditions of elevated temperatures and/or elevated temperature and pressure with a titanium metal such as titanium butoxide. The resulting fused product exhibits hydrogen desorption kinetics having a first hydrogen release point which occurs at normal atmospheres and at a temperature between 50.degree. C. and 90.degree. C.

  4. Nanostructured, complex hydride systems for hydrogen generation

    Directory of Open Access Journals (Sweden)

    Robert A. Varin

    2015-02-01

    Full Text Available Complex hydride systems for hydrogen (H2 generation for supplying fuel cells are being reviewed. In the first group, the hydride systems that are capable of generating H2 through a mechanical dehydrogenation phenomenon at the ambient temperature are discussed. There are few quite diverse systems in this group such as lithium alanate (LiAlH4 with the following additives: nanoiron (n-Fe, lithium amide (LiNH2 (a hydride/hydride system and manganese chloride MnCl2 (a hydride/halide system. Another hydride/hydride system consists of lithium amide (LiNH2 and magnesium hydride (MgH2, and finally, there is a LiBH4-FeCl2 (hydride/halide system. These hydride systems are capable of releasing from ~4 to 7 wt.% H2 at the ambient temperature during a reasonably short duration of ball milling. The second group encompasses systems that generate H2 at slightly elevated temperature (up to 100 °C. In this group lithium alanate (LiAlH4 ball milled with the nano-Fe and nano-TiN/TiC/ZrC additives is a prominent system that can relatively quickly generate up to 7 wt.% H2 at 100 °C. The other hydride is manganese borohydride (Mn(BH42 obtained by mechano-chemical activation synthesis (MCAS. In a ball milled (2LiBH4 + MnCl2 nanocomposite, Mn(BH42 co-existing with LiCl can desorb ~4.5 wt.% H2 at 100 °C within a reasonable duration of dehydrogenation. Practical application aspects of hydride systems for H2 generation/storage are also briefly discussed.

  5. Crystal structure of gold hydride

    International Nuclear Information System (INIS)

    Highlights: • Volume expansion of metal hydrides is due to the increase in the s-band filling. • AuH structure is similar to that of Hg having one more s electron compared to Au. • Structure stability of both Hg and AuH is governed by the Hume-Rothery rule. - Abstract: A number of transition metal hydrides with close-packed metal sublattices of fcc or hcp structures with hydrogen in octahedral interstitial positions were obtained by the high-pressure-hydrogen technique described by Ponyatovskii et al. (1982). In this paper we consider volume increase of metals by hydrogenation and possible crystal structure of gold hydride in relation with the structure of mercury, the nearest neighbor of Au in the Periodic table. Suggested structure of AuH has a basic tetragonal body-centered cell that is very similar to the mercury structure Hg-t I 2. The reasons of stability for this structure are discussed within the model of Fermi sphere–Brillouin zone interactions

  6. NMR study of hydride systems

    International Nuclear Information System (INIS)

    The hydrides of thorium (ThH2, Th4H15 and Th4D15) and the intermetallic compound system (Zr(Vsub(1-x)Cosub(x))2 and its hydrides were investigated using the nuclear magnetic resonance (NMR) technique. From the results for the thorium hydride samples it was concluded that the density of states at the Fermi level n(Esub(f)) is higher in Th4H15 than in ThH2; there is an indirect reaction between the protons and the d electrons belonging to the Th atoms in Th4H15; n(E) has a sharp structure near Esub(f). It was also found that the hydrogen diffusion mechanism changes with temperature. From the results for the intermetallic compound system conclusions were drawn concerning variations in the electronic structure, which explain the behavior of the system. In hydrogen diffusion studies in several samples it was found that Co atoms slow the diffusion rate. Quadrupole spectra obtained at low temperatures show that the H atoms preferably occupy tetrahedral sites formed by three V atoms and one Z atom. (H.K.)

  7. Crystal structure of gold hydride

    Energy Technology Data Exchange (ETDEWEB)

    Degtyareva, Valentina F., E-mail: degtyar@issp.ac.ru

    2015-10-05

    Highlights: • Volume expansion of metal hydrides is due to the increase in the s-band filling. • AuH structure is similar to that of Hg having one more s electron compared to Au. • Structure stability of both Hg and AuH is governed by the Hume-Rothery rule. - Abstract: A number of transition metal hydrides with close-packed metal sublattices of fcc or hcp structures with hydrogen in octahedral interstitial positions were obtained by the high-pressure-hydrogen technique described by Ponyatovskii et al. (1982). In this paper we consider volume increase of metals by hydrogenation and possible crystal structure of gold hydride in relation with the structure of mercury, the nearest neighbor of Au in the Periodic table. Suggested structure of AuH has a basic tetragonal body-centered cell that is very similar to the mercury structure Hg-t I 2. The reasons of stability for this structure are discussed within the model of Fermi sphere–Brillouin zone interactions.

  8. Activity of cesium-134 and cesium-137 in game and mushrooms in Poland

    International Nuclear Information System (INIS)

    The activity of cesium-134 and cesium-137 was measured in mushrooms and game in 1986-1991. The samples were collected all over Poland and most of the measurements were carried out for export purposes. The results indicate that the activity ratio of cesium-137 to cesium-134 in some samples is not comparable to that with fallout after the Chernobyl accident. The analysis of some samples of mushrooms from 1985 showed that the activity of cesium-137 was higher compared to any other foodstuff. The level of contamination varied greatly throughout Poland

  9. Delayed hydride cracking in Zr-2.5 % Nb: effect of hydride blisters

    International Nuclear Information System (INIS)

    In the zirconium base alloys subjected to a local thermal gradient, in presence of hydrogen, fully hydride region (frequently called blisters) can be formed. Due to the brittle character of the zirconium hydride, cracks are usually found inside the blisters. These cracks are prone to growing, under stress and temperature, by successive hydride precipitation at the crack tip. This process is called hydride induced delayed cracking (HIDC). In a previous work, hydride platelets were observed in the radial direction of the blister. In the present one, blisters were grown on Zr-2.5 wt % Nb pressure tubes. Then, tensile specimens were submitted to HIDC tests. During the test, the radial hydrides length increase due to stress concentrator effect of the blister. If a crack, that was initiated into the blister, reaches the Zr matrix therefore can propagate through the radial hydrides. (author)

  10. Kinetics of hydride front in Zircaloy-2 and H release from a fractional hydrided surface

    Energy Technology Data Exchange (ETDEWEB)

    Diaz, M.; Gonzalez-Gonzalez, A.; Moya, J. S.; Remartinez, B.; Perez, S.; Sacedon, J. L. [Instituto de Ciencia de Materiales de Madrid (CSIC), Sor Juana Ines de la Cruz 3, Cantoblanco, 28049 Madrid (Spain); Iberdrola, Tomas Redondo 3, 28033 Madrid (Spain); Instituto de Ciencia de Materiales de Madrid (CSIC), Sor Juana Ines de la Cruz 3, Cantoblanco, 28049 Madrid (Spain)

    2009-07-15

    The authors study the hydriding process on commercial nuclear fuel claddings from their inner surface using an ultrahigh vacuum method. The method allows determining the incubation and failure times of the fuel claddings, as well as the dissipated energy and the partial pressure of the desorbed H{sub 2} from the outer surface of fuel claddings during the hydriding process. The correlation between the hydriding dissipated energy and the amount of zirconium hydride (formed at different stages of the hydriding process) leads to a near t{sup 1/2} potential law corresponding to the time scaling of the reaction for the majority of the tested samples. The calibrated relation between energy and hydride thickness allows one to calculate the enthalpy of the {delta}-ZrH{sub 1.5} phase. The measured H{sub 2} desorption from the external surface is in agreement with a proposed kinetic desorption model from the hydrides precipitated at the surface.

  11. PIXE analyses of cesium in rice grains

    Science.gov (United States)

    Sugai, Hiroyuki; Ishii, Keizo; Matsuyama, Shigeo; Terakawa, Atsuki; Kikuchi, Yohei; Takahashi, Hiroaki; Ishizaki, Azusa; Fujishiro, Fumito; Arai, Hirotsugu; Osada, Naoyuki; Karahashi, Masahiro; Nozawa, Yuichiro; Yamauchi, Shosei; Kikuchi, Kosuke; Koshio, Shigeki; Watanabe, Koji

    2014-01-01

    The Fukushima nuclear power plant accident released vast amounts of radioactive material into the environment. For instance, 134Cs and 137Cs have half-lives of about 2 and 30 years, respectively, and emit many harmful gamma rays. In 2012, rice with radioactivity >100 Bq/kg was occasionally reported in Fukushima prefecture. To determine where and how cesium accumulates in rice, we grew rice in soil containing stable cesium and investigated the distribution of cesium in rice using particle-induced X-ray emission (PIXE). This study found that cesium is accumulated in bran and germ at high concentrations, and white rice contains 40% of the cesium found in brown rice.

  12. Predicting formation enthalpies of metal hydrides

    DEFF Research Database (Denmark)

    Andreasen, A.

    2004-01-01

    In order for the hydrogen based society viz. a society in which hydrogen is the primary energy carrier to become realizable an efficient way of storing hydrogen is required. For this purpose metal hydrides are serious candidates. Metal hydrides are formedby chemical reaction between hydrogen and ...

  13. Submillimeter Spectroscopy of Hydride Molecules

    Science.gov (United States)

    Phillips, T. G.

    1998-05-01

    Simple hydride molecules are of great importance in astrophysics and astrochemistry. Physically they dominate the cooling of dense, warm phases of the ISM, such as the cores and disks of YSOs. Chemically they are often stable end points of chemical reactions, or may represent important intermediate stages of the reaction chains, which can be used to test the validity of the process. Through the efforts of astronomers, physicists, chemists, and laboratory spectroscopists we have an approximate knowledge of the abundance of some of the important species, but a great deal of new effort will be required to achieve the comprehensive and accurate data set needed to determine the energy balance and firmly establish the chemical pathways. Due to the low moment of inertia, the hydrides rotate rapidly and so have their fundamental spectral lines in the submillimeter. Depending on the cloud geometry and temperature profile they may be observed in emission or absorption. Species such as HCl, HF, OH, CH, CH(+) , NH_2, NH_3, H_2O, H_2S, H_3O(+) and even H_3(+) have been detected, but this is just a fraction of the available set. Also, most deduced abundances are not nearly sufficiently well known to draw definitive conclusions about the chemical processes. For example, the most important coolant for many regions, H_2O, has a possible range of deduced abundance of a factor of 1000. The very low submillimeter opacity at the South Pole site will be a significant factor in providing a new capabilty for interstellar hydride spectroscopy. The new species and lines made available in this way will be discussed.

  14. Multiphoton ionization of atomic cesium

    International Nuclear Information System (INIS)

    We describe experimental studies of resonantly enhanced multiphoton ionization (MPI) of cesium atoms in the presence and absence of an external electric field. In the zero-field studies, photoelectron angular distributions for one- and two-photon resonantly enhanced MPI are compared with the theory of Tang and Lambropoulos. Deviations of experiment from theory are attributed to hyperfine coupling effects in the resonant intermediate state. The agreement between theory and experiment is excellent. In the absence of an external electric field, signal due to two-photon resonant three-photon ionization of cesium via np states is undetectable. Application of an electric field mixes nearby nd and ns levels, thereby inducing excitation and subsequent ionization. Signal due to two-photon excitation of ns levels in field-free experiments is weak due to their small photoionization cross section. An electric field mixes nearby np levels which again allows detectable photoionization signal. For both ns and np states the field induced MPI signal increases as the square of the electric field for a given principal quantum number and increases rapidly with n for a given field strength. Finally, we note that the classical two-photon field-ionization threshold is lower for the case in which the laser polarization and the electric field are parallel than it is when they are perpendicular. 22 references, 11 figures

  15. Activated aluminum hydride hydrogen storage compositions and uses thereof

    Science.gov (United States)

    Sandrock, Gary; Reilly, James; Graetz, Jason; Wegrzyn, James E.

    2010-11-23

    In one aspect, the invention relates to activated aluminum hydride hydrogen storage compositions containing aluminum hydride in the presence of, or absence of, hydrogen desorption stimulants. The invention particularly relates to such compositions having one or more hydrogen desorption stimulants selected from metal hydrides and metal aluminum hydrides. In another aspect, the invention relates to methods for generating hydrogen from such hydrogen storage compositions.

  16. Metal Hydrides for Rechargeable Batteries

    Energy Technology Data Exchange (ETDEWEB)

    Valoeen, Lars Ole

    2000-03-01

    Rechargeable battery systems are paramount in the power supply of modern electronic and electromechanical equipment. For the time being, the most promising secondary battery systems for the future are the lithium-ion and the nickel metal hydride (NiMH) batteries. In this thesis, metal hydrides and their properties are described with the aim of characterizing and improving those. The thesis has a special focus on the AB{sub 5} type hydrogen storage alloys, where A is a rare earth metal like lanthanum, or more commonly misch metal, which is a mixture of rare earth metals, mainly lanthanum, cerium, neodymium and praseodymium. B is a transition metal, mainly nickel, commonly with additions of aluminium, cobalt, and manganese. The misch metal composition was found to be very important for the geometry of the unit cell in AB{sub 5} type alloys, and consequently the equilibrium pressure of hydrogen in these types of alloys. The A site substitution of lanthanum by misch metal did not decrease the surface catalytic properties of AB{sub 5} type alloys. B-site substitution of nickel with other transition elements, however, substantially reduced the catalytic activity of the alloy. If the internal pressure within the electrochemical test cell was increased using inert argon gas, a considerable increase in the high rate charge/discharge performance of LaNi{sub 5} was observed. An increased internal pressure would enable the utilisation of alloys with a high hydrogen equivalent pressure in batteries. Such alloys often have favourable kinetics and high hydrogen diffusion rates and thus have a potential for improving the high current discharge rates in metal hydride batteries. The kinetic properties of metal hydride electrodes were found to improve throughout their lifetime. The activation properties were found highly dependent on the charge/discharge current. Fewer charge/discharge cycles were needed to activate the electrodes if a small current was used instead of a higher

  17. Hydrogen-storing hydride complexes

    Science.gov (United States)

    Srinivasan, Sesha S.; Niemann, Michael U.; Goswami, D. Yogi; Stefanakos, Elias K.

    2012-04-10

    A ternary hydrogen storage system having a constant stoichiometric molar ratio of LiNH.sub.2:MgH.sub.2:LiBH.sub.4 of 2:1:1. It was found that the incorporation of MgH.sub.2 particles of approximately 10 nm to 20 nm exhibit a lower initial hydrogen release temperature of 150.degree. C. Furthermore, it is observed that the particle size of LiBNH quaternary hydride has a significant effect on the hydrogen sorption concentration with an optimum size of 28 nm. The as-synthesized hydrides exhibit two main hydrogen release temperatures, one around 160.degree. C. and the other around 300.degree. C., with the main hydrogen release temperature reduced from 310.degree. C. to 270.degree. C., while hydrogen is first reversibly released at temperatures as low as 150.degree. C. with a total hydrogen capacity of 6 wt. % to 8 wt. %. Detailed thermal, capacity, structural and microstructural properties have been demonstrated and correlated with the activation energies of these materials.

  18. Surface tension of liquid dilute solutions of lead-cesium and bismuth-cesium systems

    International Nuclear Information System (INIS)

    Method of the maximal pressure in a drop was used to measure the surface tension of 15 liquid dilute solutions of lead-cesium system in 0-0.214 at% concentration range and of 12 diluted solutions of bismuth-cesium system in 0-0.160 at.% cesium range from solidification temperature up to 500 dec C. It was found that cesium was characterized as surfactant in lead and bismuth melts. It was established that the temperature coefficient of surface tension changes sufficiently in maximally diluted solutions of alkali metals in bismuth and lead melts. Effect of sodium, potassium, rubidum and cesium on the value of surface tension of lead and bismuth was systematized. Growth of activity in sodium, potassium, rubidium and cesium series was noted

  19. Experimental reproducibility analysis in DU hydriding

    Energy Technology Data Exchange (ETDEWEB)

    Koo, Daeseo; Park, Jongcheol; Chung, Hongsuk [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-10-15

    A storage and delivery system (SDS) is used for storing hydrogen isotopes as a metal hydride form. The rapid hydriding of tritium is very important not only for safety reasons but also for the economic design and operation of the SDS. For the storage, supply, and recovery of hydrogen isotopes, depleted uranium (DU) has been extensively proposed. To develop nuclear fusion technology, it will be necessary to store and supply hydrogen isotopes needed for Tokamak operation. The experimental reproducibility of bed temperature on DU hydriding was also analyzed. The experimental reproducibility of apparatus was acceptable for all the experiments. The experimental reproducibility of tank pressure on DU hydriding was analyzed. As the hydriding performs, the tank pressure showed decreasing trend. The experimental reproducibility of bed temperature on DU hydriding was also analyzed. As the hydriding performs, the bed temperatures increased up to maximum temperature with exothermic reaction and then they showed decreasing trend. The experimental reproducibility of apparatus was acceptable for all the experiments.

  20. Application of Cesium isotopes in daily life

    International Nuclear Information System (INIS)

    In the world of science, the desire of the scientific community to discover new chemical elements is crucial for the development of new technologies in various fields of knowledge. And the main chemical element addressed by this article is Cesium, but specifically 133Cesium isotope and radioisotope 137Cesium, exemplifying their physical and chemical characteristics, and their applications. This article will also show how these isotopes have provided researchers a breakthrough in the field of radiological medicine and in time and frequency metrology. (author)

  1. Decontamination of radioactive cesium in soil

    International Nuclear Information System (INIS)

    Agricultural soil containing radioactive cesium was decontaminated using an extraction method involving aqueous potassium solutions. Results demonstrated that the potassium solution could extract radioactive cesium from soil artificially contaminated with 137Cs, although extraction rate decreased as time after contamination increased. However, visual examination of radioactivity distribution in soil samples significantly contaminated by the accident at the Fukushima Daiichi nuclear power plant showed that radioactive cesium also existed as insoluble particles. Therefore, reducing the volume of radioactive wastes generated from soil decontamination requires a physical decontamination method combined with chemical treatment. (author)

  2. Studies on cesium uptake by phenolic resins

    International Nuclear Information System (INIS)

    The selective removal of cesium by phenolic ion-exchange resins from highly salted alkaline radioactive solutions was studied. The resins were synthesized by alkaline polycondensation of phenol, resorcinol, catechol, and resorcinol-catechol mixture with formaldehyde and characterized for their moisture regain, ion-exchange (H+ → Na+) capacity, and distribution coefficient (KD) for cesium. The effects of open and sealed curing of the polymers on their properties were studied. The effect of Na+, NaOH, and Cs+ concentration on the uptake of cesium by resorcinol-formaldehyde resin was investigated, in particular. The chemical, thermal, and radiation stabilities of the polymers were also studied

  3. Sorption of cesium on Latvian clays

    International Nuclear Information System (INIS)

    Cesium is like potassium - good solubility and mobile in a ground, easily assimilate in organism expressly brawn woof. It is a problem if pollutant is a radioactive 137Cs. We made experiments to sorption a 2M CsF solution on some Latvian clays which mainly contain hydro micas (cesium content after good elute of clays are in table). We establish, that clay treated with 25 % sulfuric acid adsorb cesium two times more that waste clay. Hereto unstuck elute Cs from clays. (author)

  4. Method for monitoring radioactive cesium concentration in water using cesium adsorption disk and GM survey meter

    International Nuclear Information System (INIS)

    A method for monitoring radioactive cesium concentration in water using a cesium adsorption disk and a GM survey meter has been developed to ascertain whether the water quality meets standards on radiological contaminants in water. In this method, both dissolved and suspended forms of radioactive cesium are collected on the cesium adsorption disk by means of filtration of a water sample. Beta count rate of the disk is converted into radioactivity using a conservative calibration factor obtained here. The present method was applied to monitoring of decontaminated water of an outdoor school swimming pool in Date City after Fukushima Daiichi Nuclear Power Plant accident. (author)

  5. Trapping characteristics for gaseous cesium generated from different cesium compounds by fly ash filter

    International Nuclear Information System (INIS)

    The purpose of this study is to evaluate the applicability of the fly ash ceramic foam filter to trap gaseous cesium generated during the OREOX and sintering processes of DUPIC green pellets. The trapping experiments of gaseous cesium generated from different cesium compounds using fly ash filters were carried out in a two-zone furnace under air and hydrogen (Ar/4% H2) conditions. XRD and SEM analyses were used to analyze reaction products of different cesium compounds with fly ash filters. To manufacture ceramic foam filters, fly ash with a Si/Al mole ratio of 2.1 and polyvinyl alcohol as binder were used. Reaction products formed by the trapping reaction of different cesium compounds with fly ash filters were investigated. The major reaction products of gaseous cesium generated from cesium silicate and CsI by fly ash filters indicated that pollucite (CsAlSi2O6) phase was formed under air and hydrogen conditions when the carrier gas velocity was 2 cm/sec. The minimum reaction temperature of fly ash filter with gaseous cesium was determined as about 600 deg. C. Finally, off-gas treatment system of sintering process in a hot cell of lMEF was explained as an application example of fly ash filter for trapping gaseous cesium. (author)

  6. Hydriding failure analysis based on PIE data

    International Nuclear Information System (INIS)

    Failure causes of the two fuel rods of a Korean nuclear power plant had been investigated by using PIE technique. The destructive and physico-chemical examinations revealed that the clad hydriding phenomena had caused the rod failures primarily and secondarily in each case. In this study the basic mechanisms of the primary and the secondary hydriding failures are reviewed, PIE data such as cladding inner and outer surface oxide thickness and the restructuring of fuel pellets are analyzed, and they are compared with predicted behaviors by a fuel performance code. The results strongly support that the hydriding processes, primary and secondary, had played critical roles in the respective fuel rods failures. (author)

  7. Solid hydrides as hydrogen storage reservoirs

    International Nuclear Information System (INIS)

    Metal hydrides as hydrogen storage materials are briefly reviewed in this paper. Fundamental properties of metal-hydrogen (gas) system such as Pressure-Composition-Temperature (P-C-T) characteristics are discussed on the light of the metal-hydride thermodynamics. Attention is specially paid to light metal hydrides which might have application in the car and transport sector. The pros and cons of MgH2 as a light material are outlined. Researches in course oriented to improve the behaviour of MgH2 are presented. Finally, other very promising alternative materials such as Al compounds (alanates) or borohydrides as light hydrogen accumulators are also considered. (Author)

  8. Hydride observations using the neutrography technique

    International Nuclear Information System (INIS)

    Neutron radiography observations were performed at the RA-6 experimental nuclear facility in Bariloche. Images from a prototype of a hydride-based hydrogen storage device have been obtained. The technique allows visualizing the inner hydride space distribution. The hydride appeared compacted at the lower part of the prototype after several cycles of hydrogen charge and discharge. The technique has also been applied to the study of Zr/ZrH2 samples. There is a linear relation between the sample width/hydrogen concentration and the photograph grey scale. This information could be useful for the study of nuclear engineering materials and to determine their possible degradation by hydrogen pick up (author)

  9. The electrochemical impedance of metal hydride electrodes

    DEFF Research Database (Denmark)

    Valøen, Lars Ole; Lasia, Andrzej; Jensen, Jens Oluf; Tunold, Reidar

    2002-01-01

    The electrochemical impedance responses for different laboratory type metal hydride electrodes were successfully modeled and fitted to experimental data for AB5 type hydrogen storage alloys as well as one MgNi type electrode. The models fitted the experimental data remarkably well. Several AC......, explaining the experimental impedances in a wide frequency range for electrodes of hydride forming materials mixed with copper powder, were obtained. Both charge transfer and spherical diffusion of hydrogen in the particles are important sub processes that govern the total rate of the electrochemical...... observed. The impedance analysis was found to be an efficient method for characterizing metal hydride electrodes in situ....

  10. Sintered wire cesium dispenser photocathode

    Energy Technology Data Exchange (ETDEWEB)

    Montgomery, Eric J; Ives, R. Lawrence; Falce, Louis R

    2014-03-04

    A photoelectric cathode has a work function lowering material such as cesium placed into an enclosure which couples a thermal energy from a heater to the work function lowering material. The enclosure directs the work function lowering material in vapor form through a low diffusion layer, through a free space layer, and through a uniform porosity layer, one side of which also forms a photoelectric cathode surface. The low diffusion layer may be formed from sintered powdered metal, such as tungsten, and the uniform porosity layer may be formed from wires which are sintered together to form pores between the wires which are continuous from the a back surface to a front surface which is also the photoelectric surface.

  11. Tritium removal using vanadium hydride

    International Nuclear Information System (INIS)

    The results of an initial examination of the feasibility of separation of tritium from gaseous protium-tritium mixtures using vanadium hydride in cyclic processes is reported. Interest was drawn to the vanadium-hydrogen system because of the so-called inverse isotope effect exhibited by this system. Thus the tritide is more stable than the protide, a fact which makes the system attractive for removal of tritium from a mixture in which the light isotope predominates. The initial results of three phases of the research program are reported, dealing with studies of the equilibrium and kinetics properties of isotope exchange, development of an equilibrium theory of isotope separation via heatless adsorption, and experiments on the performance of a single heatless adsorption stage. In the equilibrium and kinetics studies, measurements were made of pressure-composition isotherms, the HT--H2 separation factors and rates of HT--H2 exchange. This information was used to evaluate constants in the theory and to understand the performance of the heatless adsorption experiments. A recently developed equilibrium theory of heatless adsorption was applied to the HT--H2 separation using vanadium hydride. Using the theory it was predicted that no separation would occur by pressure cycling wholly within the β phase but that separation would occur by cycling between the β and γ phases and using high purge-to-feed ratios. Heatless adsorption experiments conducted within the β phase led to inverse separations rather than no separation. A kinetic isotope effect may be responsible. Cycling between the β and γ phases led to separation but not to the predicted complete removal of HT from the product stream, possibly because of finite rates of exchange. Further experimental and theoretical work is suggested which may ultimately make possible assessment of the feasibility and practicability of hydrogen isotope separation by this approach

  12. Cesium and strontium ion specific exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Yates, S.

    1996-10-01

    This work is one of two parallel projects that are part of an ESP task to develop high-capacity, selective, solid extractants for cesium, strontium, and technetium from nuclear wastes. In this subtask, Pacific Northwest National Laboratory (PNNL) is collaborating with AlliedSignal, Inc. (Des Plaines, Illinois) to develop inorganic ion exchangers that are selective for strontium and cesium from alkaline high-level waste and groundwater streams.

  13. Sorption of Cesium on Latvia clays

    International Nuclear Information System (INIS)

    Cesium is like potassium - good solubility and mobile in a ground, easy assimilates in organism expressly brawn woof. It is a problem if pollutant is radioactive 137Cs. We made experiments to sorption a 2M CsF solution on some Latvian clays which mainly contain hydro micas. We establish that clay treated with 25% sulfuric acid absorb cesium two times more that waste clay. Hereto unstuck elute Cs from clays

  14. Geoneutrino and Hydridic Earth model. Version 2

    OpenAIRE

    Bezrukov, Leonid

    2013-01-01

    Uranium, Thorium and Potassium-40 abundances in the Earth were calculated in the frame of Hydridic Earth model. Terrestrial heat producton from U, Th and K40 decays was calculated also. We must admit the existance of Earth expansion process to understand the obtained large value of terrestrial heat producton. The geoneutrino detector with volume more than 5 kT (LENA type) must be constructed to definitely separate between Bulk Silicat Earth model and Hydridic Earth model. In second version of...

  15. Atomistic Potentials for Palladium-Silver Hydrides

    OpenAIRE

    Hale, L. M.; Wong, B. M.; Zimmerman, J. A.; Zhou, X.

    2013-01-01

    New EAM potentials for the ternary palladium-silver-hydrogen system are developed by extending a previously developed palladium-hydrogen potential. The ternary potentials accurately capture the heat of mixing and structural properties associated with solid solution alloys of palladium-silver. Stable hydrides are produced with properties that smoothly transition across the compositions. Additions of silver to palladium are predicted to alter the properties of the hydrides by decreasing the mis...

  16. Probing the cerium/cerium hydride interface using nanoindentation

    Energy Technology Data Exchange (ETDEWEB)

    Brierley, Martin, E-mail: martin.brierley@awe.co.uk [Atomic Weapons Establishment, Aldermaston, Berkshire RG7 4PR (United Kingdom); University of Manchester, Manchester M13 9PL (United Kingdom); Knowles, John, E-mail: john.knowles@awe.co.uk [Atomic Weapons Establishment, Aldermaston, Berkshire RG7 4PR (United Kingdom)

    2015-10-05

    Highlights: • A disparity exists between the minimum energy and actual shape of a cerium hydride. • Cerium hydride is found to be harder than cerium metal by a ratio of 1.7:1. • A zone of material under compressive stress was identified surrounding the hydride. • No distribution of hardness was apparent within the hydride. - Abstract: A cerium hydride site was sectioned and the mechanical properties of the exposed phases (cerium metal, cerium hydride, oxidised cerium hydride) were measured using nanoindentation. An interfacial region under compressive stress was observed in the cerium metal surrounding a surface hydride that formed as a consequence of strain energy generated by the volume expansion associated with precipitation of the hydride phase.

  17. Probing the cerium/cerium hydride interface using nanoindentation

    International Nuclear Information System (INIS)

    Highlights: • A disparity exists between the minimum energy and actual shape of a cerium hydride. • Cerium hydride is found to be harder than cerium metal by a ratio of 1.7:1. • A zone of material under compressive stress was identified surrounding the hydride. • No distribution of hardness was apparent within the hydride. - Abstract: A cerium hydride site was sectioned and the mechanical properties of the exposed phases (cerium metal, cerium hydride, oxidised cerium hydride) were measured using nanoindentation. An interfacial region under compressive stress was observed in the cerium metal surrounding a surface hydride that formed as a consequence of strain energy generated by the volume expansion associated with precipitation of the hydride phase

  18. Influence of hydrides orientation on strain, damage and failure of hydrided zircaloy-4

    International Nuclear Information System (INIS)

    In pressurized water reactors of nuclear power plants, fuel pellets are contained in cladding tubes, made of Zirconium alloy, for instance Zircaloy-4. During their life in the primary water of the reactor (155 bars, 300 C), cladding tubes are oxidized and consequently hydrided. A part of the hydrogen given off precipitates as Zirconium hydrides in the bulk material and embrittles the material. This embrittlement depends on many parameters, among which hydrogen content and orientation of hydrides with respect to the applied stress. This investigation is devoted to the influence of the orientation of hydrides with respect to the applied stress on strain, damage and failure mechanisms. Macroscopic and SEM in-situ ring tensile tests are performed on cladding tube material (unirradiated cold worked stress-relieved Zircaloy-4) hydrided with about 200 and 500 wppm hydrogen, and with different main hydrides orientation: either parallel or perpendicular to the circumferential tensile direction. We get the mechanical response of the material as a function of hydride orientation and hydrogen content and we investigate the deformation, damage and failure mechanisms. In both cases, digital image correlation techniques are used to estimate local and global strain distributions. Neither the tensile stress-strain response nor the global and local strain modes are significantly affected by hydrogen content or hydride orientation, but the failure modes are strongly modified. Indeed, only 200 wppm radial hydrides embrittle Zy-4: sample fail in the elastic domain at about 350 MPa before strain bands could develop; whereas in other cases sample reach at least 750 MPa before necking and final failure, in ductile or brittle mode. To model this particular heterogeneous material behavior, a non-coupled damage approach which takes into account the anisotropic distribution of the hydrides is proposed. Its parameters are identified from the macroscopic strain field measurements and a

  19. Removal of cesium from wastewater: A cesium-specific ion exchange resin

    International Nuclear Information System (INIS)

    Researchers at the Savannah River Laboratory (SRL) have applied for a patent for an ion exchange resin that will remove cesium from water. Radioactive cesium-137 is a fission product of nuclear reactor operations. Cesium may enter the water of spent fuel holding basins through defects in fuel cladding. Control of cesium in these basins is desirable to keep personnel exposure to a minimum. Cesium is also present in the waste from reprocessing of defense nuclear reactor fuel. Research has been underway at SRL for over a decade to improve management of high-level reprocessing waste. The current technology separates the waste into soluble and insoluble components. Radioactive constituents are removed from the soluble component stream and combined with the insoluble components, which are then converted to a glass for long-term storage. Cesium is the most radioactive constituent of the soluble components stream. The SRL resin is a resorcinol-formaldehyde condensation polymer highly specific for cesium and is about 10 times more effective in removal of cesium than other ion exchange resins evaluated for use in processing defense nuclear waste. Tests have been run at SRL using both simulated and actual waste streams

  20. gamma-Zr-Hydride Precipitate in Irradiated Massive delta- Zr-Hydride

    DEFF Research Database (Denmark)

    Warren, M. R.; Bhattacharya, D. K.

    1975-01-01

    During examination of A Zircaloy-2-clad fuel pin, which had been part of a test fuel assembly in a boiling water reactor, several regions of severe internal hydriding were noticed in the upper-plenum end of the pin. Examination of similar fuel pins has shown that hydride of this type is caused by...

  1. Radioactive cesium in Finnish mushrooms

    International Nuclear Information System (INIS)

    Surveillance of radioactive cesium in Finnish mushrooms was started in 1986 at STUK. Results of the surveillance programs carried out in Lapland and other parts of Finland are given in this report. More than 2000 samples of edible mushrooms have been analysed during 1986-2008. The 137Cs detected in the mushrooms mainly originates from the 137Cs deposition due to the accident at the Chernobyl nuclear power plant in 1986. The 137Cs concentrations of mushrooms in the end of 1970s and in the beginning of 1980s varied from some ten to two hundred becquerels per kilogram originating from the nuclear weapon test period. The uneven division of the Chernobyl fallout is seen in the areal variation of 137Cs concentrations of mushrooms, the 137Cs concentrations being about tenfold in the areas with the highest deposition compared to those where the deposition was lowest. After the Chernobyl accident the maximum values in the 137Cs concentrations were reached during 1987-88 among most species of mushrooms. The 137Cs concentrations have decreased slowly, being in 2008 about 40 per cent of the maximum values. The 137Cs concentrations may be tenfold in the mushroom species with high uptake of cesium (Rozites caperatus, Hygrophorus camarophyllus, Lactarius trivialis) compared to the species with low uptake (Albatrellus ovinus, Leccinum sp.) picked in the same area. The 137Cs contents in certain species of commercial mushrooms in Finland still exceed the maximum permitted level, 600 Bq/kg, recommended to be respected when placing wild game, wild berries, wild mushrooms and lake fish on the market (Commission recommendation 2003/274/Euratom). Therefore, the 137Cs concentrations of mushrooms should be measured before placing them on the market in the areas of the highest 137Cs deposition, except for Albatrellus ovinus, Boletus sp. and Cantharellus cibarius. The 137Cs concentrations of common commercial mushroom species, Cantharellus tubaeformis and Craterellus cornucopioides often

  2. Plasma etching of cesium iodide

    International Nuclear Information System (INIS)

    Thick films of cesium iodide (CsI) are often used to convert x-ray images into visible light. Spreading of the visible light within CsI, however, reduces the resolution of the resulting image. Anisotropic etching of the CsI film into an array of micropixels can improve the image resolution by confining light within each pixel. The etching process uses a high-density inductively coupled plasma to pattern CsI samples held by a heated, rf-biased chuck. Fluorine-containing gases such as CF4 are found to enhance the etch rate by an order of magnitude compared to Ar+ sputtering alone. Without inert-gas ion bombardment, however, the CF4 etch becomes self-limited within a few microns of depth due to the blanket deposition of a passivation layer. Using CF4+Ar continuously removes this layer from the lateral surfaces, but the formation of a thick passivation layer on the unbombarded sidewalls of etched features is observed by scanning electron microscopy. At a substrate temperature of 220 deg. C, the minimum ion-bombardment energy for etching is Ei∼50 eV, and the rate depends on Ei1/2 above 65 eV. In dilute mixtures of CF4 and Ar, the etch rate is proportional to the gas-phase density of atomic fluorine. Above 50% CF4, however, the rate decreases, indicating the onset of net surface polymer deposition. These observations suggest that anisotropy is obtained through the ion-enhanced inhibitor etching mechanism. Etching exhibits an Arrhenius-type behavior in which the etch rate increases from ∼40 nm/min at 40 deg. C to 380 nm/min at 330 deg. C. The temperature dependence corresponds to an activation energy of 0.13±0.01 eV. This activation energy is consistent with the electronic sputtering mechanism for alkali halides

  3. Research on decontamination of cesium contaminated soil by electrokinetic process

    International Nuclear Information System (INIS)

    In this research, electrokinetic process was applied for the decontamination of cesium contaminated soil. As a result, about 4.0 times cesium removal was achieved by applying a DC electric field of 80 V/m to comparing zero electric field in treatment for 30 days. Therefore, the electrokinetic process has a possibility to decontamination of cesium contaminated soil. (author)

  4. Mechanism of corrosion of zirconium hydride and impact of precipitated hydrides on the Zircaloy-4 corrosion behaviour

    International Nuclear Information System (INIS)

    Highlights: • Higher corrosion rate of hydride compared to matrix (Zy4). • Higher oxygen diffusion coefficient through oxide formed on hydride. • Presence of Zr3O phase between hydride and oxide. • Hydrogen from the hydride phase is not integrated in the oxide during the corrosion process. - Abstract: In Pressurized Water Reactors, zirconium hydrides precipitate in the matrix and could increase the oxidation rate of the claddings. To understand their effect, corrosion tests, TEM and μ-XRD analyses have been performed. This work showed that the oxidation rate and the oxygen diffusion coefficient in the oxide formed on massive hydride are much greater than those of Zircaloy-4. Moreover, oxide characterizations indicated an additional phase indexed as the sub-oxide Zr3O between the oxide film and the massive hydride. Finally, the hydrogen of the hydrides is not incorporated in the oxide during the corrosion process

  5. Cesium ion uptake by moss (Hypnum cupressiforme)

    International Nuclear Information System (INIS)

    Lower land mosses uptake water and minerals from the atmosphere. They can collect metals polluting the air and radioactive fallout elements so they can be suitable for monitoring of these substances. Cesium ion uptake by Hypnum cupressiforme is studied by a radioactive tracer, 134Cs. The quantity of cesium ion in different celluar locations and the capacity of ion uptake is determined. The total capacity is found to be several times 10-3 mol g-1 and is therefore of the same order of magnitude as the cation exchange capacity of ion exchangers. The kinetics and reversibility of the process is studied as well. (orig.)

  6. Microbial accumulation of uranium, radium, and cesium

    International Nuclear Information System (INIS)

    Diverse microbial species varied considerably in their ability to accumulate uranium, cesium, and radium. Mechanistic differences in uranium uptake by Saccharomyces cerevisiae and Pseudomonas aeruginosa were indicated. S. serevisiae exhibited a slow (hours) surface accumulation of uranium which was subject to environmental factors, while P. aeruginosa accumulated uranium rapidly (minutes) as dense intracellular deposits and did not appear to be affected by environmental parameters. Metabolism was not required for uranium uptake by either organism. Cesium and radium were concentrated to a considerably lesser extent than uranium by the several species tested

  7. Environmental transfer of radio-cesium

    International Nuclear Information System (INIS)

    A large amount of Cs 134 and 137 were emitted from the destroyed reactors of Fukushima Daiichi Nuclear Power Station and deposited on the soil surface of vast area including forests, fields, and residential areas. The present report explains mainly land transfer behaviors of cesium which deposited on the surface soils, absorbed into soil particles as time passed on and finally became difficult to move from the particles (aging effect). Depth-distribution of radio-cesium in rice paddy and grassland as well as the change over years is presented. Changes with the passage of time of Cs 137 concentrations in leaves of spinach, wormwood, and persimmon are also provided. (S. Ohno)

  8. Crystalline silicotitanates for cesium/strontium removal

    Energy Technology Data Exchange (ETDEWEB)

    Brown, N.; Miller, J.; Sherman, J.

    1996-10-01

    A new class of inorganic ion exchangers called crystalline silicotitanates (CST) has been developed that exhibits very high selectivity for cesium and strontium in the highly alkaline radioactive wastes at the Hanford Site and other DOE sites. Tests have also shown that CSTs have high selectivity for cesium in acidic and neutral solutions. The ESP is supporting an effort at Sandia National Laboratories and Texas A & M University to further develop and characterize the important chemical and physical properties that will determine the applicability of CST to radioactive waste treatment at Hanford and other DOE facilities.

  9. Hydrogen storage in complex metal hydrides

    Directory of Open Access Journals (Sweden)

    BORISLAV BOGDANOVIĆ

    2009-02-01

    Full Text Available Complex metal hydrides such as sodium aluminohydride (NaAlH4 and sodium borohydride (NaBH4 are solid-state hydrogen-storage materials with high hydrogen capacities. They can be used in combination with fuel cells as a hydrogen source thus enabling longer operation times compared with classical metal hydrides. The most important point for a wide application of these materials is the reversibility under moderate technical conditions. At present, only NaAlH4 has favourable thermodynamic properties and can be employed as a thermally reversible means of hydrogen storage. By contrast, NaBH4 is a typical non- -reversible complex metal hydride; it reacts with water to produce hydrogen.

  10. The versatility of hydride-forming materials

    International Nuclear Information System (INIS)

    Full text: Already in 1866 it was realised by Graham that large amounts of hydrogen gas were, as he called it, occluded in pure metallic palladium. Even after more than one century of research in the field of hydrogen storage materials this area is still of great interest. This is not only due to the present-day commercial importance of rechargeable Nickel-Metal Hydride (NiMH) batteries, in which hydride-forming intermetallic materials are widely exploited, but also from a fundamental point of view where new discoveries are still being made. In this review these two areas will be highlighted on the basis of two illustrative examples. The first example relates to the application of hydride-forming bulk materials as electrodes in NiMH batteries. Several hydride-forming compounds are, in principle, available to be used as energy storage electrode material. It turned out, however, that AB5 -type compounds are most successfully applied due to their excellent electrode properties, like high storage capacity, rate capability and rapid electrode activation. Another important aspect is the electrode stability during cycling, which determines the battery cycle life. By designing multicomponent AB5 compounds it has been shown that this stability can be drastically improved. Recently, a second class of very stable compounds has been proposed. These so-called non-stoichiometric AB5+x compounds are characterised by the fact that the severe particle size reduction, always accompanying the hydride-formation process, is reduced. The stability mechanism responsible for this remarkable behaviour will be outlined. The second example relates to thin film applications. Recently, it has been found that the electronic conductivity of thin films composed of rare earth metal hydrides like, for example, yttrium hydride and gadolinium hydride, changes dramatically from metallic in the dihydride state to semiconducting in the trihydride state. In line with these conductivity changes the

  11. Stress induced reorientation of vanadium hydride

    Energy Technology Data Exchange (ETDEWEB)

    Beardsley, M. B.

    1977-10-01

    The critical stress for the reorientation of vanadium hydride was determined for the temperature range 180/sup 0/ to 280/sup 0/K using flat tensile samples containing 50 to 500 ppM hydrogen by weight. The critical stress was observed to vary from a half to a third of the macroscopic yield stress of pure vanadium over the temperature range. The vanadium hydride could not be stress induced to precipitate above its stress-free precipitation temperature by uniaxial tensile stresses or triaxial tensile stresses induced by a notch.

  12. Automotive cooling systems based on metal hydrides

    OpenAIRE

    Linder, Marc

    2010-01-01

    The present work focuses on metal hydride sorption systems as an alternative technology for automotive air-conditioning systems. Although this technology offers the possibility to increase the energy efficiency of a car (by utilising waste heat) and consequently reduces the CO2 emissions, its weight specific cooling power has so far been the main obstacle for an automotive application. Based on investigations of various metal hydrides, two alloys (LmNi4.91Sn0.15 and Ti0.99Zr0.01V0.43Fe0.09Cr0...

  13. Cesium and Strontium Separation Technologies Literature Review

    Energy Technology Data Exchange (ETDEWEB)

    T. A. Todd; T. A. Todd; J. D. Law; R. S. Herbst

    2004-03-01

    Integral to the Advanced Fuel Cycle Initiative (AFCI) Program’s proposed closed nuclear fuel cycle, the fission products cesium and strontium in the dissolved spent nuclear fuel stream are to be separated and managed separately. A comprehensive literature survey is presented to identify cesium and strontium separation technologies that have the highest potential and to focus research and development efforts on these technologies. Removal of these high-heat-emitting fission products reduces the radiation fields in subsequent fuel cycle reprocessing streams and provides a significant short-term (100 yr) heat source reduction in the repository. This, along with separation of actinides, may provide a substantial future improvement in the amount of fuel that could be stored in a geologic repository. The survey and review of the candidate cesium and strontium separation technologies are presented herein. Because the AFCI program intends to manage cesium and strontium together, technologies that simultaneously separate both elements are of the greatest interest, relative to technologies that separate only one of the two elements.

  14. Scintillator handbook with emphasis on cesium iodide

    Science.gov (United States)

    Tidd, J. L.; Dabbs, J. R.; Levine, N.

    1973-01-01

    This report provides a background of reasonable depth and reference material on scintillators in general. Particular attention is paid to the cesium iodide scintillators as used in the High Energy Astronomy Observatory (HEAO) experiments. It is intended especially for use by persons such as laboratory test personnel who need to obtain a working knowledge of these materials and their characteristics in a short time.

  15. Anomalous wetting of helium on cesium

    International Nuclear Information System (INIS)

    The authors report studies of the anomalous wetting of a cesium substrate by a liquid helium film by means of the technique of third sound. A hysteretic pre-wetting transition is observed as a function of the amount of helium in the experimental cell. 10 refs., 2 figs

  16. Effects of δ-hydride precipitation at a crack tip on crack propagation in delayed hydride cracking of Zircaloy-2

    International Nuclear Information System (INIS)

    Highlights: • Steady state crack velocity of delayed hydride cracking in Zircaloy-2 was analyzed. • A large stress peak is induced at an end of hydride by volume expansion of hydride. • Hydrogen diffuses to the stress peak, thereby accelerating steady hydride growth. • Crack velocity was estimated from the calculated hydrogen flux into the stress peak. • There was good agreement between calculation results and experimental data. -- Abstract: Delayed hydride cracking (DHC) of Zircaloy-2 is one possible mechanism for the failure of boiling water reactor fuel rods in ramp tests at high burnup. Analyses were made for hydrogen diffusion around a crack tip to estimate the crack velocity of DHC in zirconium alloys, placing importance on effects of precipitation of δ-hydride. The stress distribution around the crack tip is significantly altered by precipitation of hydride, which was strictly analyzed using a finite element computer code. Then, stress-driven hydrogen diffusion under the altered stress distribution was analyzed by a differential method. Overlapping of external stress and hydride precipitation at a crack tip induces two stress peaks; one at a crack tip and the other at the front end of the hydride precipitate. Since the latter is larger than the former, more hydrogen diffuses to the front end of the hydride precipitate, thereby accelerating hydride growth compared with that in the absence of the hydride. These results indicated that, after hydride was formed in front of the crack tip, it grew almost steadily accompanying the interaction of hydrogen diffusion, hydride growth and the stress alteration by hydride precipitation. Finally, crack velocity was estimated from the calculated hydrogen flux into the crack tip as a function of temperature, stress intensity factor and material strength. There was qualitatively good agreement between calculation results and experimental data

  17. Effect of yttrium on nucleation and growth of zirconium hydrides

    International Nuclear Information System (INIS)

    Addition of yttrium in zirconium causes precipitates of yttrium, which form two types of particles and are oxidized upon heat treatment. One type of particles with sub-micrometer scale sizes has a low population, whereas the other with nano scale sizes has a high population and cluster distribution. Owing to strong affinity of yttrium to hydrogen, the nanoparticles, mostly within the grains of the Zr–Y alloy, attract nucleation of hydrides at the clusters of the nanoparticles and cause preferential distribution of intragranular hydrides. In comparison with that of Zr, additional nanoparticles in the Zr–Y alloy impede further growth of hydride precipitates during hydriding. It is deduced that the impediment of growing hydride precipitates by the nanoparticles is developed during an auto-catalytic nucleation process, which leads to formation of thin and intragranular hydrides, favorable to mitigation of hydride embrittlement

  18. Effect of yttrium on nucleation and growth of zirconium hydrides

    Energy Technology Data Exchange (ETDEWEB)

    Li, Changji; Xiong, Liangyin; Wu, Erdong; Liu, Shi, E-mail: sliu@imr.ac.cn

    2015-02-15

    Addition of yttrium in zirconium causes precipitates of yttrium, which form two types of particles and are oxidized upon heat treatment. One type of particles with sub-micrometer scale sizes has a low population, whereas the other with nano scale sizes has a high population and cluster distribution. Owing to strong affinity of yttrium to hydrogen, the nanoparticles, mostly within the grains of the Zr–Y alloy, attract nucleation of hydrides at the clusters of the nanoparticles and cause preferential distribution of intragranular hydrides. In comparison with that of Zr, additional nanoparticles in the Zr–Y alloy impede further growth of hydride precipitates during hydriding. It is deduced that the impediment of growing hydride precipitates by the nanoparticles is developed during an auto-catalytic nucleation process, which leads to formation of thin and intragranular hydrides, favorable to mitigation of hydride embrittlement.

  19. Metal hydrides for hydrogen storage in nickel hydrogen batteries

    International Nuclear Information System (INIS)

    Metal hydride hydrogen storage in nickel hydrogen (Ni/H2) batteries has been shown to increase battery energy density and improve battery heat management capabilities. However the properties of metal hydrides in a Ni/H2 battery environment, which contains water vapor and oxygen in addition to the hydrogen, have not been well characterized. This work evaluates the use of hydrides in Ni/H2 batteries by fundamental characterization of metal hydride properties in a Ni/H2 cell environment. Hydrogen sorption properties of various hydrides have been measured in a Ni/H2 cell environment. Results of detailed thermodynamic and kinetic studies of hydrogen sorption in LaNi5 in a Ni/H2 cell environment are presented. Long-term cycling studies indicate that degradation of the hydride can be minimized by cycling between certain pressure limits. A model describing the mechanism of hydride degradation is presented

  20. Are RENiAl hydrides metallic?

    Czech Academy of Sciences Publication Activity Database

    Eichinger, K.; Havela, L.; Prokleška, J.; Stelmakhovych, O.; Daniš, S.; Šantavá, Eva; Miliyanchuk, K.

    2009-01-01

    Roč. 100, č. 9 (2009), s. 1200-1202. ISSN 1862-5282 Grant ostatní: GA ČR(CZ) GA202/07/0418 Institutional research plan: CEZ:AV0Z10100520 Keywords : rare earth metals * magnetism * hydrides Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.862, year: 2009

  1. Computational study of metal hydride cooling system

    Energy Technology Data Exchange (ETDEWEB)

    Satheesh, A.; Muthukumar, P.; Dewan, Anupam [Department of Mechanical Engineering, Indian Institute of Technology, Guwahati, Guwahati 781039 (India)

    2009-04-15

    A computational study of a metal hydride cooling system working with MmNi{sub 4.6}Al{sub 0.4}/MmNi{sub 4.6}Fe{sub 0.4} hydride pair is presented. The unsteady, two-dimensional mathematical model in an annular cylindrical configuration is solved numerically for predicting the time dependent conjugate heat and mass transfer characteristics between coupled reactors. The system of equations is solved by the fully implicit finite volume method (FVM). The effects of constant and variable wall temperature boundary conditions on the reaction bed temperature distribution, hydrogen concentration, and equilibrium pressures of the reactors are investigated. A dynamic correlation of the pressure-concentration-temperature plot is presented. At the given operating temperatures of 363/298/278 K (T{sub H}/T{sub M}/T{sub C}), the cycle time for the constant and variable wall temperature boundary conditions of a single-stage and single-effect metal hydride system are found to be 1470.0 s and 1765.6 s, respectively. The computational results are compared with the experimental data reported in the literature for LaNi{sub 4.61}Mn{sub 0.26}Al{sub 0.13}/La{sub 0.6}Y{sub 0.4}Ni{sub 4.8}Mn{sub 0.2} hydride pair and a good agreement between the two was observed. (author)

  2. Composition and process for separating cesium ions from an acidic aqueous solution also containing other ions

    Science.gov (United States)

    Dietz, M.L.; Horwitz, E.P.; Bartsch, R.A.; Barrans, R.E. Jr.; Rausch, D.

    1999-03-30

    A crown ether cesium ion extractant is disclosed as is its synthesis. The crown ether cesium ion extractant is useful for the selective purification of cesium ions from aqueous acidic media, and more particularly useful for the isolation of radioactive cesium-137 from nuclear waste streams. Processes for isolating cesium ions from aqueous acidic media using the crown ether cesium extractant are disclosed as are processes for recycling the crown ether cesium extractant and processes for recovering cesium from a crown ether cesium extractant solution. 4 figs.

  3. Strontium-90 and cesium-137 in milk

    International Nuclear Information System (INIS)

    The milk samples have been collected from 30 prefectures by prefectural public health laboratories and institutes (raw milk: 4 times per year for the report to WHO, and raw and city milk: 2 times per year), and analysed for strontium-90 and cesium-137 content at Japan Chemical Analysis Center. Collected samples were the raw milk and the city ones for the producing districts and the consuming ones, respectively. Three liters of fresh milk were carbonized in each prefectural public health laboratories and institutes, and then it was asked at Japan Chemical Analysis Center. The ask to which both some carriers and hydrochloric acid were added, was destroyed under heating. The nuclides was dissolved into hydrochloric acid and filtrated, after it was added with nitric acid and heated to dryness. The filtrate was radiochemically analysed for strontium-90 and cesium-137 using the method recommended by Science and Technology Agency. (author)

  4. Cesium stress and adaptation in pseudomonas fluorescens

    International Nuclear Information System (INIS)

    Industrialization and acid rain have led to a marked increment on the bioavailability of numerous metals. These metallic pollutants pose a serious threat to the ecosystem due to their ability to interact negatively with living organisms. Thus, considerable effort has been directed towards the development of environmentally-friendly technologies tailored to the management of metal wastes. As microbes are known to adapt to most environmental stresses, they constitute organisms of choice in the study of molecular adaptation processes. The adaptive features may be subsequently engineered for biotechnological applications. Cesium, a monovalent metal with chemical similarities to potassium but no know essential biological function has become a cause of environmental concern owing to its accidental release from the Chernobyl nuclear accident. This study examines the impact of cesium on the soil microbe Pseudomonas fluorescensts, and discusses the possibilities of its use in management of this nuclear waste. 15 refs., 3 figs

  5. Thermochemical evaluation and preparation of cesium uranates

    International Nuclear Information System (INIS)

    Two kinds of cesium uranates, Cs2UO4 and Cs2U2O7, which are predicted by thermochemical estimation to be formed in irradiated oxide fuels, were prepared from U3O8 and Cs2CO3 for measurements of the thermal expansions and thermal conductivities. In advance of the preparation, thermochemical calculations for the formation and decomposition of these cesium uranates were performed by Gibbs free energy minimizer. The preparation temperatures for Cs2UO4 and Cs2U2O7 were determined from the results of the thermochemical calculations. The prepared samples were analyzed by X-ray diffraction, which showed that the single phases of Cs2UO4 and Cs2U2O7 were formed. Thermogravimetry and differential thermal analysis were also performed on these samples, and the decomposition temperatures were evaluated. The experimental results were in good agreement with those of the thermochemical calculations. (author)

  6. Cesium legacy safety project management work plan

    International Nuclear Information System (INIS)

    This Management Work Plan (MWP) describes the process flow, quality assurance controls, and the Environment, Safety, and Health requirements of the Cesium Legacy Safety Project. This MWP provides an overview of the project goals and methods for repackaging the non-conforming Type W overpacks and packaging the CsCl powder and pellets. This MWP is not intended to apply to other activities associated with the CsCl Legacy Safety Program (i.e., clean out of South Cell)

  7. Hydrogen storage in metallic hydrides: the hydrides of magnesium-nickel alloys

    International Nuclear Information System (INIS)

    The massive and common use of hydrogen as an energy carrier requires an adequate solution to the problem of storing it. High pressure or low temperatures are not entirely satisfactory, having each a limited range of applications. Reversible metal hydrides cover a range of applications intermediate to high pressure gas and low temperature liquid hydrogen, retaining very favorable safety and energy density characteristics, both for mobile and stationary applications. This work demonstrates the technical viability of storing hydrogen in metal hydrides of magnesium-nickel alloys. Also, it shows that technology, a product of science, can be generated within an academic environment, of the goal is clear, the demand outstanding and the means available. We review briefly theoretical models relating to metal hydride properties, specially the thermodynamics properties relevant to this work. We report our experimental results on hydrides of magnesium-nickel alloys of various compositions including data on structure, hydrogen storage capacities, reaction kinetics, pressure-composition isotherms. We selected a promising alloy for mass production, built and tested a modular storage tank based on the hydrides of the alloy, with a capacity for storing 10 Nm sup(3) of hydrogen of 1 atm and 20 sup(0)C. The tank weighs 46,3 Kg and has a volume of 21 l. (author)

  8. Murine immunization by cesium-137 irradiation attenuated Schistosoma mansoni cercariae

    International Nuclear Information System (INIS)

    Cesium-137, becoming a more readily available ionizing gamma radiation source for laboratory use, was shown to effectively attenuate Schistosoma mansoni cercariae for vaccine production. In parallel comparison studies with the murine model, cesium-137 attenuated cercariae consistently afforded better protection than did the cobalt-60 prepared vaccine. Dose-response data indicated that the optimal total irradiation with cesium-137 was between 45 and 50 Krad

  9. Murine immunization by cesium-137 irradiation attenuated Schistosoma mansoni cercariae

    Energy Technology Data Exchange (ETDEWEB)

    Stek, M. Jr.; Minard, P.; Cruess, D.F.

    1984-06-01

    Cesium-137, becoming a more readily available ionizing gamma radiation source for laboratory use, was shown to effectively attenuate Schistosoma mansoni cercariae for vaccine production. In parallel comparison studies with the murine model, cesium-137 attenuated cercariae consistently afforded better protection than did the cobalt-60 prepared vaccine. Dose-response data indicated that the optimal total irradiation with cesium-137 was between 45 and 50 Krad.

  10. Sorption of cesium 137 by steel from sodium melt

    International Nuclear Information System (INIS)

    Sorption of cesium-137 radionuclide by Kh18N10T steel from sodium melt at different temperatures (150-450 deg C) has been studied. Equilibrium coefficients of cesium distribution between sodium and steel are determined, which depend on the conditions of sorption realization, such as cesium concentration in sodium melt, the content of oxygen admixture in sodium and the state of sorbing surface

  11. Cesium-137 as a radiation source

    International Nuclear Information System (INIS)

    The U.S. Department of Energy (DOE) Byproducts Utilization Program (BUP) seeks to develop and encourage widespread commercial use of defense byproducts that are produced by DOE. Cesium-l37 is one such byproduct that is radioactive and decays with emission of gamma rays. The beneficial use of this radiation to disinfect sewage sludge or disinfest food commodities is actively being pursued by the program. The radiation produced by cesium-l37(Cs-l37) is identical in form to that produced by cobalt-60(Co-60), an isotope that is widely used in commercial applications such as medical product sterilization. The choice of isotope to use depends on several factors ranging from inherent properties of the isotopes to availability and cost. The BUP, although centrally concerned with the beneficial use of Cs-l37, by investigating and assessing the feasibility of various uses hopes to define appropriate circumstances where cesium or cobalt might best be used to accomplish specific objectives. This paper discusses some of the factors that should be considered when evaluating potential uses for isotopic sources

  12. Removal of cesium from red deer meat

    International Nuclear Information System (INIS)

    The effect was studied of marinading on the reduction of cesium radionuclide activity in red deer meat contaminated by ingestion of feed containing 134Cs+137Cs from radioactive fallout following the Chernobyl accident. Two types of marinade were studied, viz., a vinegar infusion and a vinegar infusion with an addition of vegetables and spices. The meat was chopped to cubes of about 1.5 cm in size and the marinading process took place at temperatures of 5 and 11 degC. The drop of cesium content in the meat was determined by gamma spectrometry at given time intervals. The replacement of the marinade and the duration of the process were found to maximally affect efficiency. If the solution was not replaced, about 80% of cesium radionuclides were removed after seven hours of marinading. With one replacement of the infusion the drop in 134Cs+137Cs radioactivity amounted to up to 90% after seven hours of marinading. No effects were shown of vegetable additions to the vinegar infusion and of the change in temperature from 5 to 11 degC on the efficiency of the process. (author). 3 tabs., 6 refs

  13. Metal hydrides based high energy density thermal battery

    International Nuclear Information System (INIS)

    Highlights: • The principle of the thermal battery using advanced metal hydrides was demonstrated. • The thermal battery used MgH2 and TiMnV as a working pair. • High energy density can be achieved by the use of MgH2 to store thermal energy. - Abstract: A concept of thermal battery based on advanced metal hydrides was studied for heating and cooling of cabins in electric vehicles. The system utilized a pair of thermodynamically matched metal hydrides as energy storage media. The pair of hydrides that was identified and developed was: (1) catalyzed MgH2 as the high temperature hydride material, due to its high energy density and enhanced kinetics; and (2) TiV0.62Mn1.5 alloy as the matching low temperature hydride. Further, a proof-of-concept prototype was built and tested, demonstrating the potential of the system as HVAC for transportation vehicles

  14. METHOD OF FABRICATING A URANIUM-ZIRCONIUM HYDRIDE REACTOR CORE

    Science.gov (United States)

    Weeks, I.F.; Goeddel, W.V.

    1960-03-22

    A method is described of evenly dispersing uranlum metal in a zirconium hydride moderator to produce a fuel element for nuclear reactors. According to the invention enriched uranium hydride and zirconium hydride powders of 200 mesh particle size are thoroughly admixed to form a mixture containing 0.1 to 3% by weight of U/sup 235/ hydride. The mixed powders are placed in a die and pressed at 100 tons per square inch at room temperature. The resultant compacts are heated in a vacuum to 300 deg C, whereby the uranium hydride deoomposes into uranium metal and hydrogen gas. The escaping hydrogen gas forms a porous matrix of zirconium hydride, with uramum metal evenly dispersed therethrough. The advantage of the invention is that the porosity and uranium distribution of the final fuel element can be more closely determined and controlled than was possible using prior methods of producing such fuel ele- ments.

  15. SANS Measurement of Hydrides in Uranium

    International Nuclear Information System (INIS)

    SANS scattering is shown to be an effective method for detecting the presence of hydrogen precipitates in uranium. High purity polycrystalline samples of depleted uranium were given several hydriding treatments which included extended exposures to hydrogen gas at two different pressures at 630 C as well as a furnace anneal at 850 C followed by slow cooling in the near absence hydrogen gas. All samples exhibited neutron scattering that was in proportion to the expected levels of hydrogen content. While the scattering signal was strong, the shape of the scattering curve indicated that the scattering objects were large sized objects. Only by use of a very high angular resolution SANS technique was it possible to make estimates of the major diameter of the scattering objects. This analysis permits an estimate of the volume fraction and means size of the hydride precipitates in uranium

  16. NMR investigations of YMn2Hx hydrides

    International Nuclear Information System (INIS)

    The YMn2Hx hydrides with x = 1, 2, 3 were investigated by 55Mn NMR spin echo measurements at atmospheric and high pressure. Resonance lines at frequencies up to 440 MHz were observed for the hydrides, corresponding to a huge increase of the hyperfine fields at those Mn with hydrogen neighbours. At high pressure the initial decrease of the magnitude of the Mn hyperfine field of YMn2H1 at 4.2 K was found to be 4% per kbar which is an order of magnitude bigger than observed in the other magnetically ordered materials. The effects are interpreted in terms of changes of the orbital contribution and valence electron contribution to the hyperfine field caused by hydrogenation and the influence of the external pressure. (orig.)

  17. The electrochemical impedance of metal hydride electrodes

    DEFF Research Database (Denmark)

    Valøen, Lars Ole; Lasia, Andrzej; Jensen, Jens Oluf;

    2002-01-01

    The electrochemical impedance responses for different laboratory type metal hydride electrodes were successfully modeled and fitted to experimental data for AB5 type hydrogen storage alloys as well as one MgNi type electrode. The models fitted the experimental data remarkably well. Several AC......, explaining the experimental impedances in a wide frequency range for electrodes of hydride forming materials mixed with copper powder, were obtained. Both charge transfer and spherical diffusion of hydrogen in the particles are important sub processes that govern the total rate of the electrochemical...... hydrogen absorption/desorption reaction. To approximate the experimental data, equations describing the current distribution in porous electrodes were needed. Indications of one or more parallel reduction/oxidation processes competing with the electrochemical hydrogen absorption/desorption reaction were...

  18. Synthesis of metal hydrides by cold rolling

    International Nuclear Information System (INIS)

    'Full text:' In the development of metal hydrides for commercial applications, a special attention should be devoted to the ways of production. For commercial success, the raw elements of the hydrogen storage materials should be of low cost, the synthesis process should be inexpensive and easily scalable. Therefore, it is important to put some effort on the elaboration of new and more efficient means of producing metal hydrides. In this perspective, cold rolling was investigated as a new means of producing nanocrystalline materials. This technique is well-known in the industry and easily scalable. Cold rolling was performed on Mg-Ni system. The evolution of morphology, crystal structure, crystallite size, deformation, and preferred orientation was studied as a function of number of rolling passes. Cold rolling followed by a heat treatment produced the intermetallic Mg2Ni. Without heat treatment and for a large number of rolling, an amorphous phase was synthesized. (author)

  19. Numerical study of a magnesium hydride tank

    Science.gov (United States)

    Delhomme, Baptiste; de Rango, Patricia; Marty, Philippe

    2012-11-01

    Hydrogen storage in metal hydride tanks (MHT) is a very promising solution. Several experimental tanks, studied by different teams, have already proved the feasibility and the interesting performances of this solution. However, in much cases, an optimization of tank geometry is still needed in order to perform fast hydrogen loading. The development of efficient numerical tools is a key issue for MHT design and optimization. We propose a simple model representing a metal hydride tank exchanging its heat of reaction with a thermal fluid flow. In this model, the radial and axial discretisations have been decoupled by using Matlab® one-dimensional tools. Calculations are compared to experimental results obtained in a previous study. A good agreement is found for the loading case. The discharging case shows some discrepancies, which are discussed in this paper.

  20. The hydride fluoride crystal structure database, HFD

    Energy Technology Data Exchange (ETDEWEB)

    Gingl, F.; Gelato, L.; Yvon, K. [Geneva Univ. (Switzerland). Lab. Crystallographie aux Rayons X

    1997-05-20

    HFD is a new data base containing crystal structure information on more than one thousand metal hydrides and fluorides. It includes space group, cell parameters, standardized atom positions, site occupancies and references. The compilation is critical as only refined crystal structures are considered and the data are checked for internal consistency. It is comprehensive as structural information is extracted from all major scientific journals, and it is continuously updated. HFD can be searched according to various criteria such as symmetry, chemical elements, composition etc. The primary motivation for creating HFD was to predict new metal hydrides and to study their structural analogies with metal fluorides. However, HFD can also be used for other applications such as the simulation of diffraction patterns and the drawing of crystal structures. (orig.) 13 refs.

  1. Surface interactions of cesium and boric acid with stainless steel

    International Nuclear Information System (INIS)

    In this report, the effects of cesium hydroxide and boric acid on oxidized stainless steel surfaces at high temperatures and near one atmosphere of pressure are investigated. This is the first experimental investigation of this chemical system. The experimental investigations were performed using a mass spectrometer and a mass electrobalance. Surfaces from the different experiments were examined using a scanning electron microscope to identify the presence of deposited species, and electron spectroscopy for chemical analysis to identify the species deposited on the surface. A better understanding of the equilibrium thermodynamics, the kinetics of the steam-accelerated volatilizations, and the release kinetics are gained by these experiments. The release rate is characterized by bulk vaporization/gas-phase mass transfer data. The analysis couples vaporization, deposition, and desorption of the compounds formed by cesium hydroxide and boric acid under conditions similar to what is expected during certain nuclear reactor accidents. This study shows that cesium deposits on an oxidized stainless steel surface at temperatures between 1000 and 1200 Kelvin. Cesium also deposits on stainless steel surfaces coated with boric oxide in the same temperature ranges. The mechanism for cesium deposition onto the oxide layer was found to involve the chemical reaction between cesium and chromate. Some revaporization in the cesium hydroxide-boric acid system was observed. It has been found that under the conditions given, boric acid will react with cesium hydroxide to form cesium metaborate. A model is proposed for this chemical reaction

  2. Distribution and retention of cesium in Swedish boreal forest ecosystems

    International Nuclear Information System (INIS)

    The retention and distribution of cesium in forest environments are being studied at three locations in Sweden. The main part of the cesium found in the soil was recovered in horizons rich in organic matter. The cesium was retained in the soil organic matter in a more or less extractable form. As different soil types have a different distribution pattern of organic matter the distribution of cesium will depend on the forest soil type. The clay content in Swedish forest soils is in general low which will mitigate the retention of cesium in the soil mineral horizons. The cesium present in the tree was considered to be an effect of assimilation by the tissues in the canopy as well as by the roots. The redistribution of cesium within the trees was extensive which was considered to be an effect of a high mobility of cesium in the close system of a forest environment. The cesium will remain in the forest environment for a considerable time but can be removed by forest practice, by leaching out of the soil profile or by the radioactive decay. (au)

  3. Lanthanide doped strontium-barium cesium halide scintillators

    Science.gov (United States)

    Bizarri, Gregory; Bourret-Courchesne, Edith; Derenzo, Stephen E.; Borade, Ramesh B.; Gundiah, Gautam; Yan, Zewu; Hanrahan, Stephen M.; Chaudhry, Anurag; Canning, Andrew

    2015-06-09

    The present invention provides for a composition comprising an inorganic scintillator comprising an optionally lanthanide-doped strontium-barium, optionally cesium, halide, useful for detecting nuclear material.

  4. Speciesion arsenic and selenium using hydride method atomic absorption spectroscopy

    International Nuclear Information System (INIS)

    Hydrides production - atomic absorption spectroscopy system was studied. Hydrides production tool and gas-liquid separator were tested and successfully used in this work. Hydride was produced through natrium borohydride reaction with sample solution. Emitted gas was separated by gas-liquid separator before it is carried by nitrogen gas through T tube which is put in atomic absorption flame spectrophotometer. Efficiency of the system was tested through standard reference sample and seawater / sediment samples which is collected from Negeri Johor water bays

  5. Plasmonic hydrogen sensing with nanostructured metal hydrides.

    Science.gov (United States)

    Wadell, Carl; Syrenova, Svetlana; Langhammer, Christoph

    2014-12-23

    In this review, we discuss the evolution of localized surface plasmon resonance and surface plasmon resonance hydrogen sensors based on nanostructured metal hydrides, which has accelerated significantly during the past 5 years. We put particular focus on how, conceptually, plasmonic resonances can be used to study metal-hydrogen interactions at the nanoscale, both at the ensemble and at the single-nanoparticle level. Such efforts are motivated by a fundamental interest in understanding the role of nanosizing on metal hydride formation processes in the quest to develop efficient solid-state hydrogen storage materials with fast response times, reasonable thermodynamics, and acceptable long-term stability. Therefore, a brief introduction to the thermodynamics of metal hydride formation is also given. However, plasmonic hydrogen sensors not only are of academic interest as research tool in materials science but also are predicted to find more practical use as all-optical gas detectors in industrial and medical applications, as well as in a future hydrogen economy, where hydrogen is used as a carbon free energy carrier. Therefore, the wide range of different plasmonic hydrogen sensor designs already available is reviewed together with theoretical efforts to understand their fundamentals and optimize their performance in terms of sensitivity. In this context, we also highlight important challenges to be addressed in the future to take plasmonic hydrogen sensors from the laboratory to real applications in devices, including poisoning/deactivation of the active materials, sensor lifetime, and cross-sensitivity toward other gas species. PMID:25427244

  6. Sorption of cesium in intact rock

    Energy Technology Data Exchange (ETDEWEB)

    Puukko, E. [Univ. of Helsinki, Dept. of Chemistry (Finland)

    2014-04-15

    The mass distribution coefficient K{sub d} is used in performance assessment (PA) to describe sorption of a radionuclide on rock. The R{sub d} is determined using crushed rock which causes uncertainty in converting the R{sub d} values to K{sub d} values for intact rock. This work describes a method to determine the equilibrium of sorption on intact rock. The rock types of the planned Olkiluoto waste disposal site were T-series mica gneiss (T-MGN), T-series tonalite granodiorite granite gneiss (T-TGG), P-series tonalite granodiorite granite gneiss (P-TGG) and pegmatitic granite (PGR). These rocks contain different amount of biotite which is the main sorbing mineral. The sorption of cesium on intact rock slices was studied by applying an electrical field to speed up migration of cesium into the rock. Cesium is in the solution as a noncomplex cation Cs{sup +} and it is sorbed by ion exchange. The tracer used in the experiments was {sup 134}Cs. The experimental sorption on the intact rock is compared with values calculated using the in house cation exchange sorption model (HYRL model) in PHREEQC program. The observed sorption on T-MGN and T-TGG rocks was close to the calculated values. Two PGR samples were from a depth of 70 m and three samples were from a depth of 150 m. Cesium sorbed more than predicted on the two 70 m PGR samples. The sorption of Cs on the three 150 m PGR samples was small which was consistent with the calculations. The pegmatitic granite PGR has the smallest content of biotite of the four rock types. In the case of P-TGG rock the observed values of sorption were only half of the calculated values. Two kind of slices were cut from P-TGG drill core. The slices were against and to the direction of the foliation of the biotite rims. The sorption of cesium on P-TGG rock was same in both cases. The results indicated that there was no effect of the directions of the electric field and the foliation of biotite in the P-TGG rock. (orig.)

  7. METHOD AND APPARATUS FOR MAKING URANIUM-HYDRIDE COMPACTS

    Science.gov (United States)

    Wellborn, W.; Armstrong, J.R.

    1959-03-10

    A method and apparatus are presented for making compacts of pyrophoric hydrides in a continuous operation out of contact with air. It is particularly useful for the preparation of a canned compact of uranium hydride possessing high density and purity. The metallic uranium is enclosed in a container, positioned in a die body evacuated and nvert the uranium to the hydride is admitted and the container sealed. Heat is applied to bring about the formation of the hydride, following which compression is used to form the compact sealed in a container ready for use.

  8. Spectrophotometric determination of volautile inorganic hydrides in binary gaseous mixtures

    International Nuclear Information System (INIS)

    A study was made on possibility of single and continuons analysis of binary mixtures (hydride-gas) for the content of volatile inorganic hydrides (VIH) from absorption spectra in the 185-280 nm band. Dependences of the percentage of VIH transmission on the wavelength are presented. It is shown that the maximum of their absorption depends on the element-hydrogen the bond length and binding energy. Detection limit for boron hydride was established to be n x 10-3% vol at 185-190 nm wavelength. Technique for spectrophotometric hydride determination in binary mixtures with hydrogen, argon, helium was developed. The technique provides the continuous control of gaseous mixture composition

  9. Identification of the zirconium hydrides metallography in zircaloy-2

    International Nuclear Information System (INIS)

    Technique for the Identification of the zirconium hydrides in metallographic specimens have been developed. Microhardness, quantitative estimation and relative orientation of the present hydrides as well as grain size determination of the different Zircaloy-2 tube specimens have also been made. The specimens used were corrosion- tested in water during various periods of time at 300 degree castrating, prior to the metallographic examination. Reference specimens, as received, and heavily hydride specimens in a hydrogen atmosphere at 800 degree centigrees, have been used in the previous stages of the work. No difficulties have been met in this early stage of acquaintanceship with the zirconium hydrides. (Author) 5 refs

  10. Uranium-zirconium hydride fuel properties

    Energy Technology Data Exchange (ETDEWEB)

    Olander, D. [Department of Nuclear Engineering, University of California at Berkeley, Berkeley, CA 94720 (United States)], E-mail: fuelpr@nuc.berkeley.edu; Greenspan, Ehud [Department of Nuclear Engineering, University of California at Berkeley, Berkeley, CA 94720 (United States); Garkisch, Hans D. [Westinghouse Electric Company LLC, Pittsburgh, PA 15236 (United States); Petrovic, Bojan [School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA (United States)

    2009-08-15

    Properties of the two-phase hydride U{sub 0.3}ZrH{sub 1.6} pertinent to performance as a nuclear fuel for LWRs are reviewed. Much of the available data come from the Space Nuclear Auxiliary Power (SNAP) program of 4 decades ago and from the more restricted data base prepared for the TRIGA research reactors some 3 decades back. Transport, mechanical, thermal and chemical properties are summarized. A principal difference between oxide and hydride fuels is the high thermal conductivity of the latter. This feature greatly decreases the temperature drop over the fuel during operation, thereby reducing the release of fission gases to the fraction due only to recoil. However, very unusual early swelling due to void formation around the uranium particles has been observed in hydride fuels. Avoidance of this source of swelling limits the maximum fuel temperature to {approx}650 deg. C (the design limit recommended by the fuel developer is 750 deg. C). To satisfy this temperature limitation, the fuel-cladding gap needs to be bonded with a liquid metal instead of helium. Because the former has a thermal conductivity {approx}100 times larger than the latter, there is no restriction on gap thickness as there is in helium-bonded fuel rods. This opens the possibility of initial gap sizes large enough to significantly delay the onset of pellet-cladding mechanical interaction (PCMI). The large fission-product swelling rate of hydride fuel (3x that of oxide fuel) requires an initial radial fuel-cladding gap of {approx}300 m if PCMI is to be avoided. The liquid-metal bond permits operation of the fuel at current LWR linear-heat-generation rates without exceeding any design constraint. The behavior of hydrogen in the fuel is the source of phenomena during operation that are absent in oxide fuels. Because of the large heat of transport (thermal diffusivity) of H in ZrH{sub x}, redistribution of hydrogen in the temperature gradient in the fuel pellet changes the initial H/Zr ratio of 1

  11. Uranium-zirconium hydride fuel properties

    International Nuclear Information System (INIS)

    Properties of the two-phase hydride U0.3ZrH1.6 pertinent to performance as a nuclear fuel for LWRs are reviewed. Much of the available data come from the Space Nuclear Auxiliary Power (SNAP) program of 4 decades ago and from the more restricted data base prepared for the TRIGA research reactors some 3 decades back. Transport, mechanical, thermal and chemical properties are summarized. A principal difference between oxide and hydride fuels is the high thermal conductivity of the latter. This feature greatly decreases the temperature drop over the fuel during operation, thereby reducing the release of fission gases to the fraction due only to recoil. However, very unusual early swelling due to void formation around the uranium particles has been observed in hydride fuels. Avoidance of this source of swelling limits the maximum fuel temperature to ∼650 deg. C (the design limit recommended by the fuel developer is 750 deg. C). To satisfy this temperature limitation, the fuel-cladding gap needs to be bonded with a liquid metal instead of helium. Because the former has a thermal conductivity ∼100 times larger than the latter, there is no restriction on gap thickness as there is in helium-bonded fuel rods. This opens the possibility of initial gap sizes large enough to significantly delay the onset of pellet-cladding mechanical interaction (PCMI). The large fission-product swelling rate of hydride fuel (3x that of oxide fuel) requires an initial radial fuel-cladding gap of ∼300 m if PCMI is to be avoided. The liquid-metal bond permits operation of the fuel at current LWR linear-heat-generation rates without exceeding any design constraint. The behavior of hydrogen in the fuel is the source of phenomena during operation that are absent in oxide fuels. Because of the large heat of transport (thermal diffusivity) of H in ZrHx, redistribution of hydrogen in the temperature gradient in the fuel pellet changes the initial H/Zr ratio of 1.6 to ∼1.45 at the center and

  12. Stress field computation for hydride blister forming in Zr alloys

    International Nuclear Information System (INIS)

    Hydrogen migration under thermal gradient in zirconium alloys results in formation of hydride blisters. An array of blisters makes Zirconium alloy components of nuclear reactors susceptible to fracture. The whole process of hydride blister formation and fracture of these components is very complex and involves hydrogen migration under thermal gradient, hydride precipitation, straining of the matrix, setting up of hydrostatic stress gradient, enhanced hydrogen migration under the combined influence of thermal and stress gradients, stress reorientation of hydrides, cracking of hydrides, crack growth by delayed hydride cracking mechanism, interlinking of blisters and spontaneous fracture of the component. In this work we estimate the stress components in hydride blisters and the surrounding matrix for certain assumed blister depth as a function of hydride matrix yield strength ratio. The simulation was carried out for a semi ellipsoidal blister using ABAQUS finite element package. The blister formation was simulated by single step and multiple step transformation of the matrix to hydride. It is felt that the same methodology can be used to estimate the stress field around semi constrained inclusion such as hydride blister(s) in hydride forming metals like uranium, zirconium, titanium etc. and of localized corrosion products in metals and alloys. A matrix of dimension in the ratio 5 (along direction 1):1 (along direction 2) was considered for the computations. The Zr matrix having hexagonal crystal structure and faced centered cubic zirconium hydride was modeled as elastically isotropic. Both matrix and hydride was modeled to undergo linear work hardening up to ultimate tensile strength (=1.25Xyield strength), corresponding to a plastic strain of 10 percent. A small strain small displacement theory was adopted. Computations were made for an axisymmetric case with the symmetry axis along the 2 direction. Transformation of zirconium hydrogen solid solution into hydride

  13. Distillation device supplies cesium vapor at constant pressure

    Science.gov (United States)

    Basiulis, A.; Shefsiek, P. K.

    1968-01-01

    Distillation apparatus in the form of a U tube supplies small amounts of pure cesium vapor at constant pressure to a thermionic converter. The upstream leg of the U tube is connected to a vacuum pump to withdraw noncondensable impurities, the bottom portion serves as a reservoir for the liquid cesium.

  14. High ramp rate thermogravimetric analysis of zirconium(II) hydride and titanium(II) hydride

    International Nuclear Information System (INIS)

    Highlights: • A unique arc image device has been proposed for high ramp rate thermogravimetry. • Powder oxidation influences decomposition kinetics at temperatures below 933 K. • Particle size has a negligible effect on TiH2 decomposition behavior. • Improvements to the device are required to conduct accurate kinetic analysis. - Abstract: Zirconium and titanium hydride are utilized in liquid phase metal foam processing techniques. This application results in immediate exposure to molten metal and almost immediate decomposition at high temperatures. Most decomposition characterization techniques utilize slow heating rates and are unable to capture the decomposition behavior of hydrides under foam processing conditions. In order to address this issue a specialized high ramp rate thermogravimetric analyzer was created from a xenon arc image refiner. In addition to thermogravimetry, complimentary techniques including X-ray diffraction and scanning electron microscopy were used to characterize hydride decomposition and compare the results to literature. Hydrides were partially oxidized and separated into particles size ranges to evaluate the influence of these factors on decomposition. Oxidizing treatments were found to decrease decomposition rate only at temperatures below 933 K (660 °C) while particle size effects appeared to be negligible. Several improvements to the unique TGA apparatus presented in the current work are suggested to allow reliable kinetic modeling and analysis

  15. Ion and electron thermoemission of cesium alumosilicates

    International Nuclear Information System (INIS)

    Relationships between and electron thermoemission of cesium aluminosilicate were studied. Measurements were made at 5.10-8-5.10-9 Tor and temperatures up to 1400 deg C. The effect of additions refractory metals Ti, Mo, Cu and Ir was studied. Ion thermoemission in the pulse regime was also studied. Conclusions are drawn that capacity depends upon additions. The temperature dependence of thermoionic emission current has two maxima and is characterized by instability in time. A conclusion is drawn that aluminosilicate thermionic cathodes can be reckoned as cathodes of a film type

  16. Cesium-137 in grass from Chernobyl fallout

    International Nuclear Information System (INIS)

    Grass ecosystem was monitored for 137Cs, a relatively long-lived radionuclide, for about 16 years since the Chernobyl reactor accident occurred on April 26, 1986. Cesium-137 in grass gramineae or poaceae the species, ranged from 122.9 Bq kg-1 (September 4, 1986) to 5.8 mBq kg-1 (October 16, 2001) that is a range of five orders of magnitude. It was observed that there was a trend of decreasing 137Cs with time reflecting a removal half-time of 40 months (3 1/3 years), which is the ecological half-life, T ec of 137Cs in grassland

  17. Plutonium and Cesium Colloid Mediated Transport

    Science.gov (United States)

    Boukhalfa, H.; Dittrich, T.; Reimus, P. W.; Ware, D.; Erdmann, B.; Wasserman, N. L.; Abdel-Fattah, A. I.

    2013-12-01

    Plutonium and cesium have been released to the environment at many different locations worldwide and are present in spent fuel at significant levels. Accurate understanding of the mechanisms that control their fate and transport in the environment is important for the management of contaminated sites, for forensic applications, and for the development of robust repositories for the disposal of spent nuclear fuel and nuclear waste. Plutonium, which can be present in the environment in multiple oxidations states and various chemical forms including amorphous oxy(hydr)oxide phases, adsorbs/adheres very strongly to geological materials and is usually immobile in all its chemical forms. However, when associated with natural colloids, it has the potential to migrate significant distances from its point of release. Like plutonium, cesium is not very mobile and tends to remain adhered to geological materials near its release point, although its transport can be enhanced by natural colloids. However, the reactivity of plutonium and cesium are very different, so their colloid-mediated transport might be significantly different in subsurface environments. In this study, we performed controlled experiments in two identically-prepared columns; one dedicated to Pu and natural colloid transport experiments, and the other to Cs and colloid experiments. Multiple flow-through experiments were conducted in each column, with the effluent solutions being collected and re-injected into the same column two times to examine the persistence and scaling behavior of the natural colloids, Pu and Cs. The data show that that a significant fraction of colloids were retained in the first elution through each column, but the eluted colloids collected from the first run transported almost conservatively in subsequent runs. Plutonium transport tracked natural colloids in the first run but deviated from the transport of natural colloids in the second and third runs. Cesium transport tracked natural

  18. Extraction of radioactive cesium from ash of flammable radioactive material

    International Nuclear Information System (INIS)

    Huge amount of radioactive materials was released by the hydrogen explosion at Fukushima Daiichi Nuclear Power Plant due to the Great East Japan Earthquake on March 11, 2011. Suppression of the volume of radioactive materials stored by decontamination works is strongly required since the preparation of storage places is not easy. We are developing the technology for separation and concentration of radioactive cesium using nano-particle, Prussian blue, as a cesium adsorption material which has a high efficiency and good selectivity. We propose a method in which radioactive cesium is extracted from the ash of flammable materials into the water and the Prussian blue nano-particles are added to the water to collect cesium. The volume of radioactive wastes contaminated by cesium is expected to be cut down with these processes. (J.P.N.)

  19. Evaluation of electrochemical ion exchange for cesium elution

    International Nuclear Information System (INIS)

    Electrochemical elution was investigated as an alternative method to acid elution for the desorption of cesium from loaded ion exchange resins. The approach was found to have several potential advantages over existing technologies, in particular, electrochemical elution eliminates the need for addition of chemicals to elute cesium from the ion exchange resin. Also, since, in the electrochemical elution process the eluting solution is not in direct contact with the ion exchange material, very small volumes of the eluting solution can be used in a complete recycle mode in order to minimize the total volume of the cesium elute. In addition, the cesium is eluted as an alkaline solution that does not require neutralization with caustic to meet the tank farm specifications. Other advantages include easy incorporation of the electrochemical elution process into the present cesium recovery schemes

  20. A combined cesium-strontium extraction/recovery process

    International Nuclear Information System (INIS)

    A new solvent extraction process for the simultaneous extraction of cesium and strontium from acidic nitrate media is described. This process uses a solvent formulation comprised of 0.05 M di-t-butylcyclohexano-18-crown-6 (DtBuCH18C6), 0.1 M Crown 100' (a proprietary, cesium-selective derivative of dibenzo-18-crown-6), 1.2 M tributyl phosphate (TBP), and 5% (v/v) lauryl nitrile in an isoparaffinic hydrocarbon diluent. Distribution ratios for cesium and strontium from 4 M nitric acid are 4.13 and 3.46, respectively. A benchtop batch countercurrent extraction experiment indicates that >98% of the cesium and strontium initially present in the feed solution can be removed in only four extraction stages. Through proper choice of extraction and strip conditions, extracted cesium and strontium can be recovered either together or individually

  1. Electrochemical and Optical Properties of Magnesium-Alloy Hydrides Reviewed

    Directory of Open Access Journals (Sweden)

    Thirugnasambandam G. Manivasagam

    2012-10-01

    Full Text Available As potential hydrogen storage media, magnesium based hydrides have been systematically studied in order to improve reversibility, storage capacity, kinetics and thermodynamics. The present article deals with the electrochemical and optical properties of Mg alloy hydrides. Electrochemical hydrogenation, compared to conventional gas phase hydrogen loading, provides precise control with only moderate reaction conditions. Interestingly, the alloy composition determines the crystallographic nature of the metal-hydride: a structural change is induced from rutile to fluorite at 80 at.% of Mg in Mg-TM alloy, with ensuing improved hydrogen mobility and storage capacity. So far, 6 wt.% (equivalent to 1600 mAh/g of reversibly stored hydrogen in MgyTM(1-yHx (TM: Sc, Ti has been reported. Thin film forms of these metal-hydrides reveal interesting electrochromic properties as a function of hydrogen content. Optical switching occurs during (dehydrogenation between the reflective metal and the transparent metal hydride states. The chronological sequence of the optical improvements in optically active metal hydrides starts with the rare earth systems (YHx, followed by Mg rare earth alloy hydrides (MgyGd(1-yHx and concludes with Mg transition metal hydrides (MgyTM(1-yHx. In-situ optical characterization of gradient thin films during (dehydrogenation, denoted as hydrogenography, enables the monitoring of alloy composition gradients simultaneously.

  2. Kinetics of Final Degassing of Hydrogen Desorption by Metal Hydrides

    CERN Document Server

    Drozdov, I V

    2014-01-01

    The proposed model concerns the 'confluent shrinking core' scenario and reproduces the desorption kinetic after the complete decay of the stoichiometric hydride ($\\beta$-phase). The exact analytical solution is obtained, the numerical values are demonstrated by the example of magnesium hydride.

  3. High energy density battery based on complex hydrides

    Science.gov (United States)

    Zidan, Ragaiy

    2016-04-26

    A battery and process of operating a battery system is provided using high hydrogen capacity complex hydrides in an organic non-aqueous solvent that allows the transport of hydride ions such as AlH.sub.4.sup.- and metal ions during respective discharging and charging steps.

  4. Growth and decomposition of Lithium and Lithium hydride on Nickel

    DEFF Research Database (Denmark)

    Engbæk, Jakob; Nielsen, Gunver; Nielsen, Jane Hvolbæk;

    2006-01-01

    -hydride films. By only making thin films of LiH it is possible to study the stability of these hydride layers and compare it directly with the stability of pure Li without having any transport phenomena or adsorbed oxygen to obscure the results. The desorption of metallic lithium takes place at a lower...

  5. Hydrogen storage in the form of metal hydrides

    Science.gov (United States)

    Zwanziger, M. G.; Santana, C. C.; Santos, S. C.

    1984-01-01

    Reversible reactions between hydrogen and such materials as iron/titanium and magnesium/ nickel alloy may provide a means for storing hydrogen fuel. A demonstration model of an iron/titanium hydride storage bed is described. Hydrogen from the hydride storage bed powers a converted gasoline electric generator.

  6. Ultra-sonic observation in niobium hydride precipitation

    International Nuclear Information System (INIS)

    The hidrogen embrittlement of exothermic ocluders, had been considered as due to applied stress induced hydride precipitates leading to brittle fracture. The results of simultaneous measurements of macroscopic deformation and elastic change due to hydride precipitation, using the ultrasonic pulse-echo technique are showed. THen it was tested the possibility of kinectis precipitation parameters evoluation. (Author)

  7. Preferred hydride growth orientations on oxide-coated gadolinium surfaces

    International Nuclear Information System (INIS)

    Highlights: ► The preferred hydride growth orientations on gadolinium metal coated by a thin oxide layer are presented. ► A preferred growth of the (1 0 0)h plane of the face centered cubic (FCC) GdH2 is observed for the hydride spots forming below the oxidation layer. ► A change to the (1 1 1)h plane of the cubic hydride dominates for the hydride's Growth Centers. ► The texture change is attributed to the surface normal compressive stress component exerted by the oxidation layer on the developing hydride. - Abstract: The initial development of hydrides on polycrystalline gadolinium (Gd), as on some other hydride forming metals, is characterized by two sequential steps. The first step involves the rapid formation of a dense pattern of small hydride spots (referred to as the “small family” of hydrides) below the native oxidation layer. The second stage takes place when some of the “small family” nucleants (referred to as “growth centers”, GCs) break the oxide layer, leading to their rapid growth and finally to the massive hydriding of the sample. In the present study, the texture of the two hydride families was studied, by combining X-ray diffraction (XRD) analysis with a microscopic analysis of the hydride, using scanning electron microscopy (SEM) and atomic force microscopy (AFM). It has been observed that for the “small family”, a preferred growth of the (1 0 0)h plane of the cubic GdH2 takes place, whereas for the GCs, a change to the (1 1 1)h plane of the cubic hydride dominates. These preferred growth orientations were analyzed by their structure relation with the (0 0 .1)m basal plane of the Gd metal. It has been concluded that the above texture change is due to the surface normal compressive stress component exerted by the oxidation overlayer on the developing hydride, preventing the (0 0 .1)m||(1 1 1)h growth orientation. This stress is relieved upon the rupture of that overlayer and the development of the GCs, leading to the

  8. Adsorption of cesium on cement mortar from aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Volchek, Konstantin, E-mail: konstantin.volchek@ec.gc.ca [Emergencies Science and Technology Section, Environment Canada, 335 River Road, Ottawa, Ontario, Canada K1A 0H3 (Canada); Miah, Muhammed Yusuf [Emergencies Science and Technology Section, Environment Canada, 335 River Road, Ottawa, Ontario, Canada K1A 0H3 (Canada); Department of Applied Chemistry and Chemical Technology, Noakhali Science and Technology University (Bangladesh); Kuang, Wenxing; DeMaleki, Zack [Emergencies Science and Technology Section, Environment Canada, 335 River Road, Ottawa, Ontario, Canada K1A 0H3 (Canada); Tezel, F. Handan [Department of Chemical and Biological Engineering, University of Ottawa, 161 Louis-Pasteur, Ottawa, Ontario, Canada K1N 6N5 (Canada)

    2011-10-30

    Highlights: {yields} The adsorption of cesium on cement mortar was investigated in a range of temperatures and cesium concentrations. {yields} The pseudo-second order kinetic model produced a good fit with the experimental kinetic data. {yields} Equilibrium test results correlated well with the Freundlich isotherm adsorption model. {yields} The interaction between cesium ions and cement mortar was dominated by chemical adsorption. - Abstract: The adsorption of cesium on cement mortar from aqueous solutions was studied in series of bench-scale tests. The effects of cesium concentration, temperature and contact time on process kinetics and equilibrium were evaluated. Experiments were carried out in a range of initial cesium concentrations from 0.0103 to 10.88 mg L{sup -1} and temperatures from 278 to 313 K using coupons of cement mortar immersed in the solutions. Non-radioactive cesium chloride was used as a surrogate of the radioactive {sup 137}Cs. Solution samples were taken after set periods of time and analyzed by inductively coupled plasma mass spectroscopy. Depending on the initial cesium concentration, its equilibrium concentration in solution ranged from 0.0069 to 8.837 mg L{sup -1} while the respective surface concentration on coupons varied from 0.0395 to 22.34 {mu}g cm{sup -2}. Equilibrium test results correlated well with the Freundlich isotherm model for the entire test duration. Test results revealed that an increase in temperature resulted in an increase in adsorption rate and a decrease in equilibrium cesium surface concentration. Among several kinetic models considered, the pseudo-second order reaction model was found to be the best to describe the kinetic test results in the studied range of concentrations. The adsorption activation energy determined from Arrhenius equation was found to be approximately 55.9 kJ mol{sup -1} suggesting that chemisorption was the prevalent mechanism of interaction between cesium ions and cement mortar.

  9. Modular hydride beds for mobile applications

    Energy Technology Data Exchange (ETDEWEB)

    Malinowski, M.E.; Stewart, K.D.

    1997-08-01

    Design, construction, initial testing and simple thermal modeling of modular, metal hydride beds have been completed. Originally designed for supplying hydrogen to a fuel cell on a mobile vehicle, the complete bed design consists of 8 modules and is intended for use on the Palm Desert Vehicle (PDV) under development at the Schatz Energy Center, Humbolt State University. Each module contains approximately 2 kg of a commercially available, low temperature, hydride-forming metal alloy. Waste heat from the fuel cell in the form of heated water is used to desorb hydrogen from the alloy for supplying feed hydrogen to the fuel cell. In order to help determine the performance of such a modular bed system, six modules were constructed and tested. The design and construction of the modules is described in detail. Initial testing of the modules both individually and as a group showed that each module can store {approximately} 30 g of hydrogen (at 165 PSIA fill pressure, 17 C), could be filled with hydrogen in 6 minutes at a nominal, 75 standard liters/min (slm) fueling rate, and could supply hydrogen during desorption at rates of 25 slm, the maximum anticipated hydrogen fuel cell input requirement. Tests made of 5 modules as a group indicated that the behavior of the group run in parallel both in fueling and gas delivery could be directly predicted from the corresponding, single module characteristics by using an appropriate scaling factor. Simple thermal modeling of a module as an array of cylindrical, hydride-filled tubes was performed. The predictions of the model are in good agreement with experimental data.

  10. Metal hydrides for concentrating solar thermal power energy storage

    Science.gov (United States)

    Sheppard, D. A.; Paskevicius, M.; Humphries, T. D.; Felderhoff, M.; Capurso, G.; Bellosta von Colbe, J.; Dornheim, M.; Klassen, T.; Ward, P. A.; Teprovich, J. A.; Corgnale, C.; Zidan, R.; Grant, D. M.; Buckley, C. E.

    2016-04-01

    The development of alternative methods for thermal energy storage is important for improving the efficiency and decreasing the cost of concentrating solar thermal power. We focus on the underlying technology that allows metal hydrides to function as thermal energy storage (TES) systems and highlight the current state-of-the-art materials that can operate at temperatures as low as room temperature and as high as 1100 °C. The potential of metal hydrides for thermal storage is explored, while current knowledge gaps about hydride properties, such as hydride thermodynamics, intrinsic kinetics and cyclic stability, are identified. The engineering challenges associated with utilising metal hydrides for high-temperature TES are also addressed.

  11. Helium trapping at erbium oxide precipitates in erbium hydride

    Energy Technology Data Exchange (ETDEWEB)

    Foiles, Stephen M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Battaile, Corbett Chandler [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2016-02-01

    The formation of He bubbles in erbium tritides is a significant process in the aging of these materials. Due to the long-standing uncertainty about the initial nucleation process of these bubbles, there is interest in mechanisms that can lead to the localization of He in erbium hydrides. Previous work has been unable to identify nucleation sites in homogeneous erbium hydride. This work builds on the experimental observation that erbium hydrides have nano- scale erbium oxide precipitates due to the high thermodynamic stability of erbium oxide and the ubiquitous presence of oxygen during materials processing. Fundamental DFT calculations indicate that the He is energetically favored in the oxide relative to the bulk hydride. Activation energies for the motion of He in the oxide and at the oxide-hydride interface indicate that trapping is kinetically feasible. A simple kinetic Monte Carlo model is developed that demonstrates the degree of trapping of He as a function of temperature and oxide fraction.

  12. Low-frequency excitations in zirconium hydrides

    International Nuclear Information System (INIS)

    The slow inelastic neutron scattering (INS) on ZrHx systems (x = 0.38, 0.52) revealed new excitations located within the energy range 2-10 MeV. Besides the acoustic vibrations specific to α-HCP Zr and γ-FCO Zr hydride the fine structure of these excitations is clearly observed. The origin of the new observed peaks is not very clear but a proton tunneling or a resonance effect in α-Zr lattice could be taken into account

  13. Tritium immobilization and packaging using metal hydrides

    International Nuclear Information System (INIS)

    Tritium recovered from CANDU heavy water reactors will have to be packaged and stored in a safe manner. Tritium will be recovered in the elemental form, T2. Metal tritides are effective compounds in which to immobilize the tritium as a stable non-reactive solid with a high tritium capacity. The technology necessary to prepare hydrides of suitable metals, such as titanium and zirconium, have been developed and the properties of the prepared materials evaluated. Conceptual designs of packages for containing metal tritides suitable for transportation and long-term storage have been made and initial testing started. (author)

  14. Nanostructured Magnesium Hydride for Reversible Hydrogen Storage

    Science.gov (United States)

    de Rango, P.; Chaise, A.; Fruchart, D.; Miraglia, S.; Marty, Ph.

    2013-05-01

    The aim of this work was to develop suitable materials to store hydrogen in a solid state. A systematic investigation of the co-milling process of magnesium hydride with a transition metal was undertaken in order to produce nanostructured and highly reactive powders. The initiating role of the transition metal was evidenced by in situ neutron diffraction experiments. High performances in terms of thermal and mechanical behavior were achieved introducing expanded graphite and compacting the mixture to form composite materials. Absorption and desorption kinetics have been measured versus temperature and H2 pressure.

  15. Formation of hydrides blisters in zirconium alloys

    International Nuclear Information System (INIS)

    The formation of zirconium hydrides blisters in zirconium alloys due to the presence of a thermal gradient is a possible phenomenon which may occur in structural components of a reactor (pressure tubes), thus resulting a very important matter for the nuclear industry. For this reason, a series of experiments were initiated in the Hydrogen Damage Laboratory so as to obtain blisters of zirconium alloys and to study the aspects related to them. Zry-4 and Zr-2.5% Nb blisters were obtained. The propagation of a fissure present in a blister and the fracture surface were observed. The fissure propagated weakly in the blister and stopped in the Zry-4 matrix. (Author)

  16. Studies on release and deposition behaviour of cesium from contaminated sodium pools and cesium trap development for FBTR

    International Nuclear Information System (INIS)

    Investigations were carried out on the release and deposition behaviour of cesium from sodium pools in air-filled chamber in the temperature range of 673 to 873 K, using Cs-134 to simulate Cs-137. About 0.12 kg of sodium was loaded in a burn-pot together with 92.5 kBq of cesium. Experiments were carried out with 21% oxygen. Natural burning period of sodium and specific activity ratio between cesium and sodium showed a tendency to decrease and release fractions of both the species tended to increase with temperature. From the surface deposited aerosols it was observed that cesium has propensity to settle down closer to the point of release. A cesium trap has been developed for FBTR with RVC as getter material. Absorption kinetics and particle release behaviour studies pointed to its intended satisfactory performance in the plant. (author)

  17. Hydrogen in novel solid-state metal hydrides

    International Nuclear Information System (INIS)

    Solid-state metal hydrides display hydrogen densities close to that of liquid hydrogen and thus provide a safe and efficient way of storing hydrogen. As a result of recent neutron and synchrotron diffraction work some novel metal hydrides have been characterized that shed new light on the nature of metal-hydrogen interactions. While hydrogen appears as an anion surrounded by a large inventory of cation configurations in ionic hydrides such as Ca4Mg3H14, Ca19Mg8H54, Eu2MgD6, Eu6Mg7D26 and Eu2Mg3D10, it acts as a terminal ligand in covalently bonded hydride complexes based on p-elements such as [BH4]- and d-elements such as [IrH5]4- and [IrH4]5- in the complex hydrides LiBH4 and Mg6Ir2H11, respectively. Surprisingly, hydride complexes and hydride anions can also be discerned in typically metallic (interstitial) hydrides such as NdMgNi4H4 (= Nd3+Mg+2.[Ni4H4]5-) and LaMg2NiD7 (= La3+Mg+22.[NiH4]4-.3H-). Some hydrides also reveal other interesting features such as a hydrogenation induced Ce4+→Ce3+ valence change in CeMn1.8Al0.2H4.4 at room temperature that is accompanied by a Mn/Al metal atom exchange over distances of ∝2.6 A, and a hydrogen induced metal-to-nonmetal transition near ambient conditions that leads from the metallic compound Mg3Ir to the red colored hydride Mg6Ir2H11. In this article recent work and some methodological aspects are highlighted. (orig.)

  18. Results of NDE Technique Evaluation of Clad Hydrides

    Energy Technology Data Exchange (ETDEWEB)

    Dennis C. Kunerth

    2014-09-01

    This report fulfills the M4 milestone, M4FT-14IN0805023, Results of NDE Technique Evaluation of Clad Hydrides, under Work Package Number FT-14IN080502. During service, zirconium alloy fuel cladding will degrade via corrosion/oxidation. Hydrogen, a byproduct of the oxidation process, will be absorbed into the cladding and eventually form hydrides due to low hydrogen solubility limits. The hydride phase is detrimental to the mechanical properties of the cladding and therefore it is important to be able to detect and characterize the presence of this constituent within the cladding. Presently, hydrides are evaluated using destructive examination. If nondestructive evaluation techniques can be used to detect and characterize the hydrides, the potential exists to significantly increase test sample coverage while reducing evaluation time and cost. To demonstrate the viability this approach, an initial evaluation of eddy current and ultrasonic techniques were performed to demonstrate the basic ability to these techniques to detect hydrides or their effects on the microstructure. Conventional continuous wave eddy current techniques were applied to zirconium based cladding test samples thermally processed with hydrogen gas to promote the absorption of hydrogen and subsequent formation of hydrides. The results of the evaluation demonstrate that eddy current inspection approaches have the potential to detect both the physical damage induced by hydrides, e.g. blisters and cracking, as well as the combined effects of absorbed hydrogen and hydride precipitates on the electrical properties of the zirconium alloy. Similarly, measurements of ultrasonic wave velocities indicate changes in the elastic properties resulting from the combined effects of absorbed hydrogen and hydride precipitates as well as changes in geometry in regions of severe degradation. However, for both approaches, the signal responses intended to make the desired measurement incorporate a number of contributing

  19. Sympathetic cooling in a rubidium cesium mixture: Production of ultracold cesium atoms

    International Nuclear Information System (INIS)

    This thesis presents experiments for the production of ultracold rubidium cesium mixture in a magnetic trap. The long-termed aim of the experiment is the study of the interaction of few cesium atoms with a Bose-Einstein condensate of rubidium atoms. Especially by controlled variation of the cesium atom number the transition in the description of the interaction by concepts of the one-particle physics to the description by concepts of the many-particle physics shall be studied. The rubidium atoms are trapped in a magneto-optical trap (MOT) and from there reloaded into a magnetic trap. In this the rubidium atoms are stored in the state vertical stroke f=2,mf=2 right angle of the electronic ground state and evaporatively cooled by means of microwave-induced transitions into the state vertical stroke f=1,mf=1] (microwave cooling). The cesium atoms are also trppaed in a MOT and into the same magnetic trap reloaded, in which they are stored in the state vertical stroke f=4,mf=4 right angle of the electronic ground state together with rubidium. Because of the different hyperfine splitting only rubidium is evaporatively cooled, while cesium is cooled jointly sympathetically - i.e. by theramal contact via elastic collisions with rubidium atoms. The first two chapters contain a description of interatomic interactions in ultracold gases as well as a short summary of theoretical concepts in the description of Bose-Einstein condensates. The chapters 3 and 4 contain a short presentation of the methods applied in the experiment for the production of ultracold gases as well as the experimental arrangement; especially in the framework of this thesis a new coil system has been designed, which offers in view of future experiments additionally optical access for an optical trap. Additionally the fourth chapter contains an extensive description of the experimental cycle, which is applied in order to store rubidium and cesium atoms together into the magnetic trap. The last chapter

  20. Development of hydride absorber for fast reactor. Application of hafnium hydride to control rod of large fast reactor

    International Nuclear Information System (INIS)

    The application of hafnium hydride (Hf-hydride) to a control rod for a large fast reactor where the B4C control rod is originally employed is studied. Three types of Hf-hydride control rods are designed. The control rod worth and its change during the burnup are evaluated for different hydrogen-to-hafnium ratios and are compared with those of the original B4C control rod. The result indicates that the worths of the Hf-hydride and the 10B-enriched B4C control rods are approximately the same, and the lifetime of the Hf-hydride control rod is almost four times longer than that of the 10B-enriched B4C control rod. The core performances of the shutdown margin, sodium void reactivity, Doppler reactivity coefficient, and breeding ratio are analyzed. It is indicated that those for the Hf-hydride control rod are almost the same as those for the original B4C control rod. The behavior of neutrons moderated by the Hf-hydride control rod is analyzed. It is confirmed that the Hf-hydride control rod does not cause any thermal spike problems in the fast reactor core. (author)

  1. Nanoindentation measurements of the mechanical properties of zirconium matrix and hydrides in unirradiated pre-hydrided nuclear fuel cladding

    Energy Technology Data Exchange (ETDEWEB)

    Rico, A., E-mail: alvaro.rico@urjc.es [DIMME, Departamento de Tecnología Mecánica, Universidad Rey Juan Carlos, c/Tulipán s/n, E-28933 Móstoles, Madrid (Spain); Martin-Rengel, M.A., E-mail: mamartin@mater.upm.es [Departamento de Ciencia de los Materiales, UPM, E.T.S.I. Caminos, Canales y Puertos, Profesor Aranguren SN, E-28040 Madrid (Spain); Ruiz-Hervias, J., E-mail: jesus.ruiz@upm.es [Departamento de Ciencia de los Materiales, UPM, E.T.S.I. Caminos, Canales y Puertos, Profesor Aranguren SN, E-28040 Madrid (Spain); Rodriguez, J. [DIMME, Departamento de Tecnología Mecánica, Universidad Rey Juan Carlos, c/Tulipán s/n, E-28933 Móstoles, Madrid (Spain); Gomez-Sanchez, F.J., E-mail: javier.gomez@amsimulation.com [Advanced Material Simulation, S.L, Madrid (Spain)

    2014-09-15

    It is well known that the mechanical properties of the nuclear fuel cladding may be affected by the presence of hydrides. The average mechanical properties of hydrided cladding have been extensively investigated from a macroscopic point of view. In addition, the mechanical and fracture properties of bulk hydride samples fabricated from zirconium plates have also been reported. In this paper, Young’s modulus, hardness and yield stress are measured for each phase, namely zirconium hydrides and matrix, of pre-hydrided nuclear fuel cladding. To this end, nanoindentation tests were performed on ZIRLO samples in as-received state, on a hydride blister and in samples with 150 and 1200 ppm of hydrogen homogeneously distributed along the hoop direction of the cladding. The results show that the measured mechanical properties of the zirconium hydrides and ZIRLO matrix (Young’s modulus, hardness and yield stress) are rather similar. From the experimental data, the hydride volume fraction in the cladding samples with 150 and 1200 ppm was estimated and the average mechanical properties were calculated by means of the rule of mixtures. These values were compared with those obtained from ring compression tests. Good agreement between the results obtained by both methods was found.

  2. Microbial uptake of uranium, cesium, and radium

    International Nuclear Information System (INIS)

    The ability of diverse microbial species to concentrate uranium, cesium, and radium was examined. Saccharomyces cerevisiae, Pseudomonas aeruginosa, and a mixed culture of denitrifying bacteria accumulated uranium to 10 to 15% of the dry cell weight. Only a fraction of the cells in a given population had visible uranium deposits in electron micrographs. While metabolism was not required for uranium uptake, mechanistic differences in the metal uptake process were indicated. Uranium accumulated slowly (hours) on the surface of S. cerevisiae and was subject to environmental factors (i.e., temperature, pH, interfering cations and anions). In contrast, P. aeruginosa and the mixed culture of denitrifying bacteria accumulated uranium rapidly (minutes) as dense, apparently random, intracellular deposits. This very rapid accumulation has prevented us from determining whether the uptake rate during the transient between the initial and equilibrium distribution of uranium is affected by environmental conditions. However, the final equilibrium distributions are not affected by those conditions which affect uptake by S. cerevisiae. Cesium and radium were concentrated to a considerably lesser extent than uranium by the several microbial species tested. The potential utility of microorganisms for the removal and concentration of these metals from nuclear processing wastes and several bioreactor designs for contacting microorganisms with contaminated waste streams will be discussed

  3. Intense non-relativistic cesium ion beam

    International Nuclear Information System (INIS)

    The Heavy Ion Fusion group at Lawrence Berkeley Laboratory has constructed the One Ampere Cesium Injector as a proof of principle source to supply an induction linac with a high charge density and high brightness ion beam. This is studied here. An electron beam probe was developed as the major diagnostic tool for characterizing ion beam space charge. Electron beam probe data inversion is accomplished with the EBEAM code and a parametrically adjusted model radial charge distribution. The longitudinal charge distribution was not derived, although it is possible to do so. The radial charge distribution that is derived reveals an unexpected halo of trapped electrons surrounding the ion beam. A charge fluid theory of the effect of finite electron temperature on the focusing of neutralized ion beams (Nucl. Fus. 21, 529 (1981)) is applied to the problem of the Cesium beam final focus at the end of the injector. It is shown that the theory's predictions and assumptions are consistent with the experimental data, and that it accounts for the observed ion beam radius of approx. 5 cm, and the electron halo, including the determination of an electron Debye length of approx. 10 cm

  4. Cesium separation Using Electrically Switched Ion Exchange

    International Nuclear Information System (INIS)

    Electrically Switched Ion Exchange (ESIX) is a separation technology being developed at Pacific Northwest National Laboratory as an alternative to conventional ion exchange for removing metal ions from wastewater. In ESIX, which combines ion exchange and electro-chemistry, ion uptake and elution can be controlled directly by modulating the potential of an ion exchange film that has been electrochemically deposited onto an electrode. This paper presents the results of experiments on high surface area electrodes and the development of a flow system for cesium ion separation. Bench-scale flow system studies showed no change in capacity or performance of the ESIX films at a flow rate up to 113 BV/h, the maxi-mum flow rate tested, and breakthrough curves supported once-through waste processing. A comparison of results for a stacked 5-electrode cell versus a single-electrode cell showed enhanced breakthrough performance. In the stacked configuration, break-through began at about 120 BV for a feed containing 0.2 ppm cesium at a flow rate of 13 BV/h. A case study for the KE Basin (a spent nuclear fuel storage basin) on the Hanford Site demonstrated that KE Basin wastewater could be processed continuously with minimal waste generation, reduced disposal costs, and lower capital expenditures

  5. Biosorption behavior and mechanism of cesium-137 on Rhodosporidium fluviale strain UA2 isolated from cesium solution

    International Nuclear Information System (INIS)

    In order to identify a more efficient biosorbent for 137Cs, we have investigated the biosorption behavior and mechanism of 137Cs on Rhodosporidium fluviale (R. fluviale) strain UA2, one of the dominant species of a fungal group isolated from a stable cesium solution. We observed that the biosorption of 137Cs on R. fluviale strain UA2 was a fast and pH-dependent process in the solution composed of R. fluviale strain UA2 (5 g/L) and cesium (1 mg/L). While a Langmuir isotherm equation indicated that the biosorption of 137Cs was a monolayer adsorption, the biosorption behavior implied that R. fluviale strain UA2 adsorbed cesium ions by electrostatic attraction. The TEM analysis revealed that cesium ions were absorbed into the cytoplasm of R. fluviale strain UA2 across the cell membrane, not merely fixed on the cell surface, which implied that a mechanism of metal uptake contributed largely to the cesium biosorption process. Moreover, PIXE and EPBS analyses showed that ion-exchange was another biosorption mechanism for the cell biosorption of 137Cs, in which the decreased potassium ions were replaced by cesium ions. All the above results implied that the biosorption of 137Cs on R. fluviale strain UA2 involved a two-step process. The first step is passive biosorption that cesium ions are adsorbed to cells surface by electrostatic attraction; after that, the second step is active biosorption that cesium ions penetrate the cell membrane and accumulate in the cytoplasm. - Highlights: • Microorganisms isolated from a cesium solution are considered as a biosorbent to remove cesium ions. • The biosorption equilibrium is fitted well to a Langmuir model with a correlation coefficient of 0.9997. • First attempt to explore biosorption mechanisms using PIXE and EPBS. • Living and dead microorganisms have different biosorption mechanisms. • The biosorption of 137Cs involved a two-step process: passive and active

  6. Neutron scattering on hydrides of intermetallic compounds

    International Nuclear Information System (INIS)

    This review surveys the application of neutron scattering for the investigation of the microscopic behaviour of hydrogen in intermetallic compounds. This concerns the structure as well as the dynamics. Neutron diffraction experiments were performed on Ti1.2Mn1.8D3 and LaNi5D7. In the latter case the dominant nickel scattering could be suppressed by isotope substitution with 60Ni, and the anisotropic broadening of the Bragg peaks could be modelled in a correspondingly modified Rietveld-profile refinement. For the investigation of hydrogen diffusion in intermetallic hydrides by means of quasielastic neutron scattering an iterative multiple scattering correction procedure has been developped which allows a reliable determination of hydrogen diffusion coefficients. The mechanism of hydrogen diffusion in intermetallic hydrides comprises three types of jumps: escape jumps out of energetically lower interstitials, transport jumps over the energetically higher sites and locally restricted jump processes. For Ti1.2Mn1.8H3 the main features of the diffusional behaviour could be described quantitatively in the framework of a three state model. By means of neutron vibrational spectroscopy information about the occupied hydrogen sites and thus about the structure can be extracted from the symmetry splitting of the vibrational modes. In this way we showed that in α-LaNi5Hx, La2Ni4-octahedral and La2Ni2-tetrahedral interstitial sites are occupied. (orig./GG)

  7. Millimeter-Wave Spectroscopy of Ethylmercury Hydride

    Science.gov (United States)

    Goubet, M.; Motiyenko, R. A.; Margulès, L.; Guillemin, J.-C.

    2012-06-01

    The first millimeter-wave rotational spectrum of an organomercury compound, ethylmercury hydride (CH_3CH_2HgH), has been recorded using the Lille fast-scan spectrometer in the frequency range 120 -- 180 GHz. The spectroscopic study is complemented by quantum chemical calculations taking into account relativistic effects on the mercury atom. The very good agreement between theoretical and experimental molecular parameters validates the chosen ab initio method, in particular its capability to predict the accurate values of the quartic centrifugal distortion constants related to this type of compound. Estimations of the nuclear quadrupole coupling constants are not as predictive as the structural parameters but good enough to satisfy the spectroscopic needs. In addition, the orientation of the H--Hg--C bonds axis deduced from the experimental nuclear quadrupole coupling constants compares well with the corresponding ab initio value. From the good agreement between experimental and theoretical results, together with the observation of the six most abundant isotopes of mercury, ethylmercury hydride is unambiguously identified and its calculated equilibrium geometry is confirmed. Alekseev, E.A. et al. Radio Physics and Radio Astronomy 3 (2012) 78.

  8. NATO Advanced Study Institute on Metal Hydrides

    CERN Document Server

    1981-01-01

    In the last five years, the study of metal hydrides has ex­ panded enormously due to the potential technological importance of this class of materials in hydrogen based energy conversion schemes. The scope of this activity has been worldwide among the industrially advanced nations. There has been a consensus among researchers in both fundamental and applied areas that a more basic understanding of the properties of metal/hydrogen syster;,s is required in order to provide a rational basis for the selection of materials for specific applications. The current worldwide need for and interest in research in metal hydrides indicated the timeliness of an Advanced Study Insti­ tute to provide an in-depth view of the field for those active in its various aspects. The inclusion of speakers from non-NATO coun­ tries provided the opportunity for cross-fertilization of ideas for future research. While the emphasis of the Institute was on basic properties, there was a conscious effort to stimulate interest in the applic...

  9. Metal hydrides for lithium-ion batteries.

    Science.gov (United States)

    Oumellal, Y; Rougier, A; Nazri, G A; Tarascon, J-M; Aymard, L

    2008-11-01

    Classical electrodes for Li-ion technology operate via an insertion/de-insertion process. Recently, conversion electrodes have shown the capability of greater capacity, but have so far suffered from a marked hysteresis in voltage between charge and discharge, leading to poor energy efficiency and voltages. Here, we present the electrochemical reactivity of MgH(2) with Li that constitutes the first use of a metal-hydride electrode for Li-ion batteries. The MgH(2) electrode shows a large, reversible capacity of 1,480 mAh g(-1) at an average voltage of 0.5 V versus Li(+)/Li(o) which is suitable for the negative electrode. In addition, it shows the lowest polarization for conversion electrodes. The electrochemical reaction results in formation of a composite containing Mg embedded in a LiH matrix, which on charging converts back to MgH(2). Furthermore, the reaction is not specific to MgH(2), as other metal or intermetallic hydrides show similar reactivity towards Li. Equally promising, the reaction produces nanosized Mg and MgH(2), which show enhanced hydrogen sorption/desorption kinetics. We hope that such findings can pave the way for designing nanoscale active metal elements with applications in hydrogen storage and lithium-ion batteries. PMID:18849978

  10. Spatial variability and Cesium-137 inventories in native forest

    International Nuclear Information System (INIS)

    With the nuclear fission discovery and development of nuclear weapons in 1940s, artificial radioisotopes were introduced in the environment. This contamination is due to worldwide fallout by superficial nuclear tests realized from early 1950s to late 1970s by USA, former URSS, UK, France and China. One of theses radioisotopes that have been very studied is cesium-137. Cesium-137 has a half-life of 30.2 years and its biological behavior is similar to the potassium. The behavior in soil matrix, depth distribution, spatial variability and inventories values of cesium-137 has been determinate for several regions of the world. In Brazil, some research groups have worked on this subject, but there are few works published about theses properties of cesium-137. The aim of this paper was study the depth distribution, spatial variability, and inventory of cesium-137 in native forest. Two native forests (Mata 1 and Mata UEL) were sampling in region of Londrina, PR. The results shows that there is a spatial variability of 40% for Mata 1 and 42% for Mata UEL. The depth distribution of cesium-137 for two forests presented a exponential form, characteristic to undisturbed soil. Cesium-137 inventory determinate for Mata 1 was 358 Bq m-2 and for Mata UEL was 320 Bq m-2. (author)

  11. Synthesis and hydride transfer reactions of cobalt and nickel hydride complexes to BX3 compounds.

    Science.gov (United States)

    Mock, Michael T; Potter, Robert G; O'Hagan, Molly J; Camaioni, Donald M; Dougherty, William G; Kassel, W Scott; DuBois, Daniel L

    2011-12-01

    Hydrides of numerous transition metal complexes can be generated by the heterolytic cleavage of H(2) gas such that they offer alternatives to using main group hydrides in the regeneration of ammonia borane, a compound that has been intensely studied for hydrogen storage applications. Previously, we reported that HRh(dmpe)(2) (dmpe = 1,2-bis(dimethylphosphinoethane)) was capable of reducing a variety of BX(3) compounds having a hydride affinity (HA) greater than or equal to the HA of BEt(3). This study examines the reactivity of less expensive cobalt and nickel hydride complexes, HCo(dmpe)(2) and [HNi(dmpe)(2)](+), to form B-H bonds. The hydride donor abilities (ΔG(H(-))°) of HCo(dmpe)(2) and [HNi(dmpe)(2)](+) were positioned on a previously established scale in acetonitrile that is cross-referenced with calculated HAs of BX(3) compounds. The collective data guided our selection of BX(3) compounds to investigate and aided our analysis of factors that determine favorability of hydride transfer. HCo(dmpe)(2) was observed to transfer H(-) to BX(3) compounds with X = H, OC(6)F(5), and SPh. The reaction with B(SPh)(3) is accompanied by the formation of dmpe-(BH(3))(2) and dmpe-(BH(2)(SPh))(2) products that follow from a reduction of multiple B-SPh bonds and a loss of dmpe ligands from cobalt. Reactions between HCo(dmpe)(2) and B(SPh)(3) in the presence of triethylamine result in the formation of Et(3)N-BH(2)SPh and Et(3)N-BH(3) with no loss of a dmpe ligand. Reactions of the cationic complex [HNi(dmpe)(2)](+) with B(SPh)(3) under analogous conditions give Et(3)N-BH(2)SPh as the final product along with the nickel-thiolate complex [Ni(dmpe)(2)(SPh)](+). The synthesis and characterization of HCo(dedpe)(2) (dedpe = Et(2)PCH(2)CH(2)PPh(2)) from H(2) and a base is also discussed, including the formation of an uncommon trans dihydride species, trans-[(H)(2)Co(dedpe)(2)][BF(4)]. PMID:22040085

  12. Effect of metal hydrides on the burning characteristics of boron

    International Nuclear Information System (INIS)

    Highlights: • The effect of some metal hydrides on the burning characteristics of boron is studied for the first time. • We are the first to conduct a TG experiment on boron samples at high temperatures (a maximum of 1750 °C). • The thermal reaction process of boron is firstly divided into five stages according to the weight gain rate of the sample. • Specific values of metal hydrides on ignition delay time and combustion intensity of boron are obtained. - Abstract: In this study, the effect of four metal hydrides on the burning characteristics of boron was investigated. Thermogravimetric experiment results show that the thermal reaction process of boron samples can be divided into five stages. The thermal reactions of boron can be significantly promoted with LiH, which can reduce the initial temperature of the first violent reaction stage by ∼140 °C. The starting temperature of the post-reaction stage also decreases by ∼260 °C. The results of the laser ignition experiment suggest that all four metal hydrides can promote boron burning. Nonetheless, different metal hydrides display varied promotional effects. Among the studied hydrides, LiH is the most effective additive and shortens the ignition delay time of boron by ∼34.1%. Moreover, it enhances the combustion intensity of boron by ∼117.6%. The other three metal hydrides (CaH2, TiH2, and ZrH2) can also contribute to boron burning

  13. Zircaloy-4 hydriding. Hydrogen distribution in PWR's rod cladding

    International Nuclear Information System (INIS)

    In pressurised water reactors, Zircaloy 4 is used as fuel cladding in contact with hot water. The precipitation of hydrides at room temperatures causes mechanical deterioration of the cladding. As the cladding is subjected to a radial temperature gradient, the hydrogen distribution is greatly affected. The image analysis method is used to determine the hydride distribution in the irradiated cladding. To calibrate this method, a device was specially built for the preparation of Zircaloy specimens with known hydrogen contents. The hydriding conditions and hydrogen content determination procedures were fixed. We have successfully realized specimens with various hydrogen contents. With these specimens, a relationship between the parameter Sv (surface density of hydrides) and the hydrogen content was established. This parameter Sv is independent from the Zircaloy 4 metallurgical state (i.e. stress relieved or recrystallized) and from the analysis section (longitudinal or transverse). Study of hydrogen content and hydride distribution in irradiated cladding by means of image analysis showed that the method is limited by its ability of separation between neighbouring hydrides at cladding's periphery where the hydrogen content can reach several thousands ppm. Nevertheless, this method gives us some information about hydride distribution inside the cladding. A model for thermal diffusion was developped to stimulate the migration of hydrogen in Zirconium alloys. This model was used to predict hydrogen distribution in the irradiated cladding. Comparison of model predictions with results of image analysis shows good agreement. (Author). refs., figs., tabs

  14. Isotope exchange between gaseous hydrogen and uranium hydride powder

    International Nuclear Information System (INIS)

    Highlights: • Isotope exchange between hydrogen gas and uranium hydride powder can be rapid and reversible. • Gas–solid exchange rate is controlled by transport within ∼0.7 μm hydride particles. • Gas chromatographic separation of hydrogen isotopes using uranium hydride is feasible. - Abstract: Isotope exchange between gaseous hydrogen and solid uranium hydride has been studied by flowing hydrogen (deuterium) gas through packed powder beds of uranium deuteride (hydride). We used a residual gas analyzer system to perform real-time analysis of the effluent gas composition. We also developed an exchange and transport model and, by fitting it to the experimental data, extracted kinetic parameters for the isotope exchange reaction. Our results suggest that, from approximately 70 to 700 kPa and 25 to 400 °C, the gas-to-solid exchange rate is controlled by hydrogen and deuterium transport within the ∼0.7 μm diameter uranium hydride particles. We use our kinetic parameters to show that gas chromatographic separation of hydrogen and deuterium using uranium hydride could be feasible

  15. Pollution of drug-technical materials by cesium-137

    International Nuclear Information System (INIS)

    Drug-technical raw materials are medicinal plants (flowers, folium, grasses, mushrooms, roots, fruits, berry, kidney, cortex), used in pharmacy. To limit receipt cesium-137 in people body in 1993 in the Republic of Belarus were created 'Temporary permission levels of the cesium-137 radionuclides contents in drug-technical raw materials' were created (TPL-1993). The permission levels of cesium-137 are following: for drug-technical raw material (flowers, folium, grass, mushrooms, roots and other plants parts) - 1850 Bq/kg, for dried up fruits and berries - 2590 Bq/kg. (Author)

  16. Synthesis and peculiarities of the cesium zeolite crystal structure (cesite)

    International Nuclear Information System (INIS)

    An attempt is made to synthesize cesium zeolite by introduction of amorphous seed crystals which correspond by composition with cesium-containing zeolite into the aluminosilicate gel, since this method can produce zeolite with a crystal structure it would not adopt under the usual conditions. It is seen that during crystablization upon introduction of a seed crystal the cesium content in zeolite decreases. A more complete structural elucidation of zeolite obtained by the suggested method was carried out by x0ray and IR spectral analyses. The data of x-ray analysis showed that the structures of synthesized zeolite and binary octagonal pores are similar

  17. The development of metal hydrides using as concentrating solar thermal storage materials

    Science.gov (United States)

    Qu, Xuanhui; Li, Yang; Li, Ping; Wan, Qi; Zhai, Fuqiang

    2015-12-01

    Metal hydrides high temperature thermal heat storage technique has great promising future prospects in solar power generation, industrial waste heat utilization and peak load regulating of power system. This article introduces basic principle of metal hydrides for thermal storage, and summarizes developments in advanced metal hydrides high-temperature thermal storage materials, numerical simulation and thermodynamic calculation in thermal storage systems, and metal hydrides thermal storage prototypes. Finally, the future metal hydrides high temperature thermal heat storage technique is been looked ahead.

  18. Management of cesium loaded AMP- Part I preparation of 137Cesium concentrate and cementation of secondary wastes

    International Nuclear Information System (INIS)

    Separation of 137cesium from High Level Waste can be achieved by use of composite-AMP, an engineered form of Ammonium Molybdo-Phosphate(AMP). Direct vitrification of cesium loaded composite AMP in borosilicate glass matrix leads to separation of water soluble molybdate phase. A proposed process describes two different routes of selective separation of molybdates and phosphate to obtain solutions of cesium concentrates. Elution of 137Cesium from composite-AMP by decomposing it under flow conditions using saturated barium hydroxide was investigated. This method leaves molybdate and phosphate embedded in the column but only 70% of total cesium loaded on column could be eluted. Alternatively composite-AMP was dissolved in sodium hydroxide and precipitation of barium molybdate-phosphate from the resultant solution, using barium nitrate was investigated by batch methods. The precipitation technique gave over 99.9% of 137Cesium activity in solutions, free of molybdates and phosphates, which is ideally suited for immobilization in borosilicate glass matrix. Detailed studies were carried out to immobilize secondary waste of 137Cesium contaminated barium molybdate-phosphate precipitates in the slag cement matrix using vermiculite and bentonite as admixtures. The cumulative fraction of 137Cs leached from the cement matrix blocks was 0.05 in 140 days while the 137Cs leach rate was 0.001 gm/cm2/d. (author)

  19. Structural relationships in complex hydrides of the late transition metals

    International Nuclear Information System (INIS)

    Literature data on complex hydrides of the late transition metals (groups 7-10), such as the hydrogen storage material Mg2NiH4, are reviewed with respect to order-disorder phase transitions and structural relationships. They are analysed in terms of crystallographic group-subgroup trees and their use in understanding the different crystal structures from a symmetry point of view is demonstrated. New data are presented on the low temperature behaviour of magnesium iridium hydrides and strontium rhodium hydrides studied by powder X-ray diffraction. (orig.)

  20. Technical and economic aspects of hydrogen storage in metal hydrides

    Science.gov (United States)

    Schmitt, R.

    1981-01-01

    The recovery of hydrogen from such metal hydrides as LiH, MgH2, TiH2, CaH2 and FeTiH compounds is studied, with the aim of evaluating the viability of the technique for the storage of hydrogen fuel. The pressure-temperature dependence of the reactions, enthalpies of formation, the kinetics of the hydrogen absorption and desorption, and the mechanical and chemical stability of the metal hydrides are taken into account in the evaluation. Economic aspects are considered. Development of portable metal hydride hydrogen storage reservoirs is also mentioned.

  1. PIE techniques for hydride reorientation test at NDC

    International Nuclear Information System (INIS)

    Dry storage of spent fuels in the interim storage facility is being planned in Japan. However, the gradual deterioration of the mechanical property of fuel cladding due to internal pressure and temperature during the storage term is known. Therefore, the integrity of stored fuel rods should be confirmed before the start of dry storage. For the last several years, NDC had a lot of experiences on the hydride reorientation test. The specimen preparation techniques on the hydride reorientation test and the mechanical testing techniques after the hydride reorientation are shown in this paper. (author)

  2. Biosorption of uranium, radium, and cesium

    International Nuclear Information System (INIS)

    Some fundamental aspects of the biosorption of metals by microbial cells were investigated. These studies were carried out in conjunction with efforts to develop a process to utilize microbial cells as biosorbents for the removal of radionuclides from waste streams generated by the nuclear fuel cycle. It was felt that an understanding of the mechanism(s) of metal uptake would potentially enable the enhancement of the metal uptake phenomenon through environmental or genetic manipulation of the microorganisms. Also presented are the results of a preliminary investigation of the applicability of microorganisms for the removal of 137cesium and 226radium from existing waste solutions. The studies were directed primarily at a characterization of uranium uptake by the yeast, Saccharomyces cerevisiae, and the bacterium, Pseudomonas aeruginosa

  3. Structure of double hafnium and cesium sulfate

    International Nuclear Information System (INIS)

    The structure of a compound whose formula according to the structural investigation is Cssub(2+x)Hf(SOsub(4))sub(2+x)(HSOsub(4))sub(2-x)x3Hsub(2)O (x approximately 0.7) (a=10.220, b=12.004, c=15.767 A, space group Pcmn) is determined by diffractometric data (2840 reflections, anisotropic refinement, R=0.087). It is build of complex unions [Hf(SO4)4H2O]4-, Cs+ cations and water molecules. Eight O atoms surrounding Hf atom (dodecahedron Hf-O 2.10-2.22 A) belong to four sulphate groups and water molecule. Three sulphate groups are bidentate-cyclic, and one group - monodentate relative to Hf. The structure has a cesium deficit in particular positions

  4. Double manganese(III) cesium triphosphate

    International Nuclear Information System (INIS)

    Double triphosphates have been identified in research on interactions in the P2O5-M2O3-Cs2O-H2O system, where M(III) = Al, Ga, Cr, Fe, at 570-770K, which have the M(III)Cs2 - P3O10 composition; here we report the identification of a new phase made under analogous conditions in a system containing Mn(III) together with some of its physicochemical properties. The product was analyzed for phosphorus by a colorimetric method, for manganese by titration with EDTA, and for cesium by atomic absorption. The x-ray phase analysis was performed with a DRON-3.0 diffractometer. The IR spectra were recorded. Thermogravimetry indicates that the product is MnCs2P3O10·H2O

  5. Low-work-function surfaces produced by cesium carbonate decomposition

    Science.gov (United States)

    Briere, T. R.; Sommer, A. H.

    1977-01-01

    Cesium carbonate (Cs2CO3) was heated to the decomposition temperature of approximately 600 C. The nonvolatile decomposition products were condensed on a nickel substrate while the carbon dioxide was removed by pumping. The deposited material is characterized by an effective work function of between 1.05 and 1.15 eV at 450 K and by photoemission in the visible and near-infrared region of the spectrum. It is suggested that the deposited material consists of Cs2O, possibly Cs2O2, and adsorbed cesium. Silver, evaporated from a heated silver bead, produced the typical photoemissive and thermionic properties of a silver-oxygen-cesium (S-1) photocathode. The material may be of interest for thermionic energy converters and for the formation of silver-oxygen-cesium photocathodes.

  6. Sorption of cesium and strontium by arid region desert soil

    International Nuclear Information System (INIS)

    Adsorption and ion exchange in soil systems are the principal mechanisms that retard the migration of nuclear waste to the biosphere. Cesium and strontium are two elements with radioactive isotopes (Cs137 and Sr90) that are commonly disposed of as nuclear waste. The sorption and ion exchange properties of nonradioactive cesium and strontium were studied in this investigation. The soil used in this study was collected at an experimental infiltration site on Frenchman Flat, a closed drainage basin on the Nevada Test Site. This soil is mostly nonsaline-alkali sandy loam and loamy sand with a cation exchange capacity ranging from 13 to 30 me/100g. The clay fraction of the soil contains illite, montmorillonite, and clinoptilolite. Ion exchange studies have shown that this soil sorbs cesium preferentially relative to strontium, and that charge for charge, the exchange-phase cations released from exchange sites exceed the cesium and strontium sorbed by the soil. 38 references, 22 figures

  7. Cesium iodide crystals fused to vacuum tube faceplates

    Science.gov (United States)

    Fleck, H. G.

    1964-01-01

    A cesium iodide crystal is fused to the lithium fluoride faceplate of a photon scintillator image tube. The conventional silver chloride solder is then used to attach the faceplate to the metal support.

  8. Delayed hydride in zirconium based alloys

    International Nuclear Information System (INIS)

    Delayed Hydride Cracking (DHC) velocity along the axial direction of Zirconium-2.5% Nb pressure tube materials of different origins i.e. CANDU and RBMK (TMT -I), has been determined in the temperature range of 162 to 250 degree C. DHC crack growth was monitored using Direct Current Potential Drop Technique. It has been observed that the DHC velocity of both materials increases with increase in test temperature. The DHC velocity for the RBMK (TMT -I) material was found about 2 to 5 times lower than that for the CANDU materials at each temperature. In addition, the activation energy of the phenomena was calculated taking into account that DHC is a thermal activated mechanism, following an Arrhenius-type law. (author)

  9. The progress of nanocrystalline hydride electrode materials

    International Nuclear Information System (INIS)

    This paper reviews research at the Institute of Materials Science and Engineering, Poznan University of Technology, on the synthesis of nanocrystalline hydride electrode materials. Nanocrystalline materials have been synthesized by mechanical alloying (MA) followed by annealing. Examples of the materials include TiFe-, ZrV2-, LaNi5 and Mg2Ni-type phases. Details on the process used and the enhancement of properties due to the nanoscale structures are presented. The synthesized alloys were used as negative electrode materials for Ni-MH battery. The properties of hydrogen host materials can be modified substantially by alloying to obtain the desired storage characteristics. For example, it was found that the respective replacement of Fe in TiFe by Ni and/or by Cr, Co, Mo improved not only the discharge capacity but also the cycle life of these electrodes. The hydrogen storage properties of nanocrystalline ZrV2- and LaNi5-type powders prepared by mechanical alloying and annealing show no big difference with those of melt casting (polycrystalline) alloys. On the other hand, a partial substitution of Mg by Mn or Al in Mg2Ni alloy leads to an increase in discharge capacity, at room temperature. Furthermore, the effect of the nickel and graphite coating on the structure of some nanocrystalline alloys and the electrodes characteristics were investigated. In the case of Mg2Ni-type alloy mechanical coating with graphite effectively reduced the degradation rate of the studied electrode materials. The combination of a nanocrystalline TiFe-, ZrV2- and LaNi5-type hydride electrodes and a nickel positive electrode to form a Ni-MH battery, has been successful. (authors)

  10. Hydrogen storage in sodium aluminum hydride.

    Energy Technology Data Exchange (ETDEWEB)

    Ozolins, Vidvuds; Herberg, J.L. (Lawrence Livermore National Laboratories, Livermore, CA); McCarty, Kevin F.; Maxwell, Robert S. (Lawrence Livermore National Laboratories, Livermore, CA); Stumpf, Roland Rudolph; Majzoub, Eric H.

    2005-11-01

    Sodium aluminum hydride, NaAlH{sub 4}, has been studied for use as a hydrogen storage material. The effect of Ti, as a few mol. % dopant in the system to increase kinetics of hydrogen sorption, is studied with respect to changes in lattice structure of the crystal. No Ti substitution is found in the crystal lattice. Electronic structure calculations indicate that the NaAlH{sub 4} and Na{sub 3}AlH{sub 6} structures are complex-ionic hydrides with Na{sup +} cations and AlH{sub 4}{sup -} and AlH{sub 6}{sup 3-} anions, respectively. Compound formation studies indicate the primary Ti-compound formed when doping the material at 33 at. % is TiAl{sub 3} , and likely Ti-Al compounds at lower doping rates. A general study of sorption kinetics of NaAlH{sub 4}, when doped with a variety of Ti-halide compounds, indicates a uniform response with the kinetics similar for all dopants. NMR multiple quantum studies of solution-doped samples indicate solvent interaction with the doped alanate. Raman spectroscopy was used to study the lattice dynamics of NaAlH{sub 4}, and illustrated the molecular ionic nature of the lattice as a separation of vibrational modes between the AlH{sub 4}{sup -} anion-modes and lattice-modes. In-situ Raman measurements indicate a stable AlH{sub 4}{sup -} anion that is stable at the melting temperature of NaAlH{sub 4}, indicating that Ti-dopants must affect the Al-H bond strength.

  11. Sorption of cesium on Olkiluoto mica gneiss, granodiorite and granite

    International Nuclear Information System (INIS)

    Cesium was selected as a model to study the sorption in bedrock occurring by ion exchange mechanism. The aim of the study was to supplement the existing data on sorption occurring by ion exchange mechanism in bedrock of the candidate sites for spent fuel disposal at Olkiluoto. The sorption of cesium was studied on crushed mica gneiss, tonalite (granodiorite) and granite in artificial groundwaters. Fresh water was represented by Allard water, pH 8 and pH 7, and saline water by Ol-So water, pH 7 and pH 9. In addition, a Na-Ca-Cl brine water and its 1:10 dilution were used as simulants. Cesium concentrations were between 10-8 and 10-3 mol/l. The distribution coefficients of the sorption, Rd and Ra values were determined by batch method. Isotherms were partly non-linear with slopes 0.7 - 1.0 depending on rock and water. At the end of the sorption experiment, the water was analysed for cations exchanged for cesium. The sorption of cesium was also studied as a function of ionic strength. The ionic strength increased in the order Allard < 0l-Br 1:10 < 0l-So < 0l-Br. The sorption of cesium was lower at higher ionic strength and higher Cs concentration. The mineral composition of rocks was determined by thin section analysis, and the sorption distribution ratios on thin sections in the different waters were determined by batch technique. The minerals, that sorbed most cesium were determined by autoradiography. These were biotite, muscovite and chlorite. Cordierite in mica gneiss also sorbed cesium very effectively. (orig.)

  12. Sorption of cesium on Olkiluoto mica gneiss, granodiorite and granite

    Energy Technology Data Exchange (ETDEWEB)

    Huitti, T.; Hakanen, M. [Univ. of Helsinki (Finland). Lab. of Radiochemistry; Lindberg, A. [Geological Survey of Finland, Espoo (Finland)

    1998-09-01

    Cesium was selected as a model to study the sorption in bedrock occurring by ion exchange mechanism. The aim of the study was to supplement the existing data on sorption occurring by ion exchange mechanism in bedrock of the candidate sites for spent fuel disposal at Olkiluoto. The sorption of cesium was studied on crushed mica gneiss, tonalite (granodiorite) and granite in artificial groundwaters. Fresh water was represented by Allard water, pH 8 and pH 7, and saline water by Ol-So water, pH 7 and pH 9. In addition, a Na-Ca-Cl brine water and its 1:10 dilution were used as simulants. Cesium concentrations were between 10{sup -8} and 10{sup -3} mol/l. The distribution coefficients of the sorption, R{sub d} and R{sub a} values were determined by batch method. Isotherms were partly non-linear with slopes 0.7 - 1.0 depending on rock and water. At the end of the sorption experiment, the water was analysed for cations exchanged for cesium. The sorption of cesium was also studied as a function of ionic strength. The ionic strength increased in the order Allard < 0l-Br 1:10 < 0l-So < 0l-Br. The sorption of cesium was lower at higher ionic strength and higher Cs concentration. The mineral composition of rocks was determined by thin section analysis, and the sorption distribution ratios on thin sections in the different waters were determined by batch technique. The minerals, that sorbed most cesium were determined by autoradiography. These were biotite, muscovite and chlorite. Cordierite in mica gneiss also sorbed cesium very effectively. (orig.) 12 refs.

  13. Cesium pre-implantation of embedded biological sections

    International Nuclear Information System (INIS)

    An ion implantation system which allows the implantation of a large surface of a specimen has been used to obtain an homogeneous enrichment with cesium of embedded biological tissues sections. In such a specimen, containing already oxygen at a high concentration, the addition of cesium allows both positive and negative secondary ions to be studied with the highest sensitivity, using the same primary ion source.

  14. Kelvin Probe Studies of Cesium Telluride Photocathode for AWA Photoinjector

    OpenAIRE

    Wisniewski, Eric; Velazquez, Daniel; Yusof, Zikri; Spentzouris, Linda; Terry, Jeff; Harkay, Katherine

    2012-01-01

    Cesium telluride is an important photocathode as an electron source for particle accelerators. It has a relatively high quantum efficiency (>1%), is sufficiently robust in a photoinjector, and has a long lifetime. This photocathode is grown in-house for a new Argonne Wakefield Accelerator (AWA) beamline to produce high charge per bunch (~50 nC) in a long bunch train. Here, we present a study of the work function of cesium telluride photocathode using the Kelvin Probe technique. The study incl...

  15. Adsorption Behaviour of Liquid 4He on Cesium Substrates

    OpenAIRE

    Iov, Valentin

    2004-01-01

    The aim of this thesis is to investigate the wetting properties of 4He on cesium substrates using optical and electrical methods. Due to the fact that the cesium substrates are deposited at low temperatures onto a thin silver underlayer, it is necessary firstly to study and understand the adsorption of helium on silver. The work presented here is structured as follows: some of the fundamental concepts on the theory of physisorbed films, such as van der Waals interaction, adsorption isotherms ...

  16. Artificial exomuscle investigations for applications-metal hydride

    International Nuclear Information System (INIS)

    In pursuing the development of bionic devices, Victhom identified a need for technologies that could replace current motorized systems and be better integrated into the human body motion. The actuators used to obtain large displacements are noisy, heavy, and do not adequately reproduce human muscle behavior. Subsequently, a project at Victhom was devoted to the development of active materials to obtain an artificial exomuscle actuator. An exhaustive literature review was done at Victhom to identify promising active materials for the development of artificial muscles. According to this review, metal hydrides were identified as a promising technology for artificial muscle development. Victhom's investigations focused on determining metal hydride actuator potential in the context of bionics technology. Based on metal hydride properties and artificial muscle requirements such as force, displacement and rise time, an exomuscle was built. In addition, a finite element model, including heat and mass transfer in the metal hydride, was developed and implemented in FEMLAB software. (review article)

  17. Artificial exomuscle investigations for applications-metal hydride

    Energy Technology Data Exchange (ETDEWEB)

    Crevier, Marie-Charlotte; Richard, Martin; Rittenhouse, D Matheson; Roy, Pierre-Olivier; Bedard, Stephane [Victhom Human Bionics Inc., Saint-Augustin-de-Desmaures, QC (Canada)

    2007-03-01

    In pursuing the development of bionic devices, Victhom identified a need for technologies that could replace current motorized systems and be better integrated into the human body motion. The actuators used to obtain large displacements are noisy, heavy, and do not adequately reproduce human muscle behavior. Subsequently, a project at Victhom was devoted to the development of active materials to obtain an artificial exomuscle actuator. An exhaustive literature review was done at Victhom to identify promising active materials for the development of artificial muscles. According to this review, metal hydrides were identified as a promising technology for artificial muscle development. Victhom's investigations focused on determining metal hydride actuator potential in the context of bionics technology. Based on metal hydride properties and artificial muscle requirements such as force, displacement and rise time, an exomuscle was built. In addition, a finite element model, including heat and mass transfer in the metal hydride, was developed and implemented in FEMLAB software. (review article)

  18. Formation of hydride blisters in zirconium alloy pressure tubes

    International Nuclear Information System (INIS)

    The fracture of the Zircaloy-2 pressure tube in the Pickering Unit 2 power reactor was associated with the growth of hydride blisters at points of contact between the pressure tube and the cooler calandria tube surrounding it. Similar blisters have been observed in a Zr-2.5 wt% Nb pressure tube in WR-1, an organic-cooled research reactor. These hydride blisters were formed and grew as a result of the thermal diffusion of hydrogen in the zirconium, a mechanism whereby hydrogen diffuses down a temperature gradient. If the terminal solid solubility of hydrogen is exceeded in the cooler regions, hydride will precipitate. In this paper, the time required to grow these hydride blisters will be estimated from the blister size and the hydrogen distribution in its neighborhood, by using simple equations derived from thermal diffusion theory

  19. Out-of-pile accelerated hydriding of Zircaloy fasteners

    International Nuclear Information System (INIS)

    Mechanical joints between Zircaloy and nickel-bearing alloys, mainly the Zircaloy-4/Inconel-600 combination, were exposed to water at 4500F and 5200F to study hydriding of Zircaloy in contact with a dissimilar metal. Accelerated hydriding of the Zircaloy occurred at both temperatures. At 4500F the dissolved hydrogen level of the water was over ten times that at 5200F. At 5200F the initially high hydrogen ingress rate decreased rapidly as exposure time increased and was effectively shut off in about 25 days. Severely hydrided Zircaloy components successfully withstood thermal cycling and mechanical testing. Chromium plating of the nickel-bearing parts was found to be an effective and practical barrier in preventing nickel-alloy smearing and accelerated hydriding of Zircaloy

  20. A nuclear analytical model for uranium zirconium hydride reactor core

    International Nuclear Information System (INIS)

    The nuclear analytical model and codes for the uranium zirconium hydride reactor are outlined. The criticality and control rods effeciency of abroad TRIGA reactor are obtained using this model and codes. The results are satisfactory

  1. A mechanistic approach to develop the secondary hydriding criteria

    International Nuclear Information System (INIS)

    Reliable criteria of secondary hydriding failures are important to assure safe operation of nuclear fuel in LWR power units. The present paper reviews available data on massive hydriding of Zirconium claddings covering out-of-pile studies and in-pile tests in research reactors. Analyses of these experimental data give evidence that threshold conditions leading to the onset of massive hydriding are drastically changed under irradiation. The changes are caused mainly by irradiation damage of oxygen sublattice in ZrO2 by fission fragments leaving the periphery of fuel pellets. The tests in research reactors provide a basis to develop a parametric dependency which relates the threshold of massive hydriding to composition of steam-hydrogen mixture, irradiation dose rate and temperature

  2. Study of strontium and cesium migration in fractured crystalline rock

    International Nuclear Information System (INIS)

    The purpose of this investigation has been to study the retardation and dilution of non-active strontium and cesium relative to a non-absorbing substance (iodide) in a well-defined fracture zone in the Finnsjoen field research area. The investigation was carried out in a previously tracer-tested fracture zone. The study has encompassed two separate test runs with prolonged injection of strontium and iodide and of cesium and iodide. The test have shown that: - Strontium is not retarded, but rather absorbed to about 40% at equilibrium. - At injection stop, 36.3% of the injected mass of strontium has been absorbed and there is no deabsorption. -Cesium is retarded a factor of 2-3 and absorbed to about 30% at equilibrium. - At injection stop, 39.4% of the injected mass of cesium has been absorbed. Cesium is deabsorbed after injection stop (400h) and after 1300 hours, only 22% of the injected mass of cesium is absorbed. (author)

  3. Transparent yttrium hydride thin films prepared by reactive sputtering

    OpenAIRE

    Mongstad, T.; Platzer-Björkman, C.; Karazhanov, S. Zh.; Holt, A.; Maehlen, J. P.; Hauback, B. C.

    2011-01-01

    Metal hydrides have earlier been suggested for utilization in solar cells. With this as a motivation we have prepared thin films of yttrium hydride by reactive magnetron sputter deposition. The resulting films are metallic for low partial pressure of hydrogen during the deposition, and black or yellow-transparent for higher partial pressure of hydrogen. Both metallic and semiconducting transparent YHx films have been prepared directly in-situ without the need of capping layers and post-deposi...

  4. The Production of Uranium Metal by Metal Hydrides Incorporated

    Energy Technology Data Exchange (ETDEWEB)

    Alexander, P. P.

    1943-01-01

    Metal Hydrides Incorporated was a pioneer in the production of uranium metal on a commercial scale and supplied it to all the laboratories interested in the original research, before other methods for its production were developed. Metal Hydrides Inc. supplied the major part of the metal for the construction of the first experimental pile which, on December 2, 1942, demonstrated the feasibility of the self-sustaining chain reaction and the release of atomic energy.

  5. Electronic structure and optical properties of lightweight metal hydrides

    NARCIS (Netherlands)

    Setten, van M.J.; Popa, V.A.; Wijs, de G.A.; Brocks, G.

    2007-01-01

    We study the dielectric functions of the series of simple hydrides LiH, NaH, MgH2, and AlH3, and of the complex hydrides Li3AlH6, Na3AlH6, LiAlH4, NaAlH4, and Mg(AlH4)2, using first-principles density-functional theory and GW calculations. All compounds are large gap insulators with GW single-partic

  6. Thin-film metal hydrides for solar energy applications

    OpenAIRE

    2012-01-01

    Thin-film metal hydrides may become important solar energy materials in the future. This thesis demonstrates interesting material properties of metal hydride films, relevant for applications as semiconducting materials for photovoltaic (PV) solar cells and for regulation of light using smart window technology. List of papers. Papers II-VI are removed from the thesis due to copyright restrictions. Paper I C. Platzer-Björkman, T. Mongstad, S. Zh. Karazhanov, J. P. Mæhlen, E. S. Marst...

  7. Suppression of the critical temperature in binary vanadium hydrides

    International Nuclear Information System (INIS)

    Highlights: • Addition of 10 mol% Cr to V increases the β-hydride TC to >200 °C. • Addition of 10 mol% Ni to V increases the β-hydride TC to >400 °C. • Addition of 10 mol% Al to V decreases the β-hydride TC to 90Al10 membrane can be cycled to 2 without β-hydride formation. -- Abstract: The tendency of vanadium-based alloy membranes to embrittle is the biggest commercialisation barrier for this hydrogen separation technology. Excessive hydrogen absorption and the α → β hydride transition both contribute to brittle failure of these membranes. Alloying is known to reduce absorption, but the influence of alloying on hydride phase formation under conditions relevant to membrane operation has not been studied in great detail previously. Here, the effect of Cr, Ni, and Al alloying additions on V–H phase equilibrium has been studied using hydrogen absorption measurements and in situ X-ray diffraction studies. The addition of 10 mol% Ni increases the critical temperature for α + β hydride formation to greater than 400 °C, compared to 170 °C for V. Cr also increases the critical temperature, to between 200 and 300 °C. The addition of 10 mol% Al, however, suppresses the critical temperature to less than 30 °C, thereby enabling this material to be cycled thermally and hydrostatically while precluding formation of the β-hydride phase. This is despite Al also decreasing hydrogen absorption. The implication of this finding is that one of the mechanisms of brittle failure in vanadium-based hydrogen-selective membranes has been eliminated, thereby increasing the robustness of this material relative to V

  8. Modelling of fuel rod hydriding failures in water reactors

    International Nuclear Information System (INIS)

    Mechanistic models which were developed to describe primary hydriding phenomena in claddings of initially intact rods with residual moisture are described. The models include the following key processes: fuel rod thermal behavior, UO2 fuel oxidation in steam-hydrogen atmosphere under irradiation, hydrogen diffusion in zirconium and in the hydride, growth of the hydride phase. Fuel rod thermomechanical behavior is calculated by using RTOP integral fuel code. An oxidation model represents the effects of temperature dynamics and temperature profile along fuel axis and radius on fuel oxidation as well as on hydrogen accumulation inside the fuel rod. Along with ordinary thermal dissociation of water molecules, the oxidation model also addresses radiolysis of the steam-hydrogen mixture due to fission fragments. The present radiolysis model takes into account the effects of the gas mixture composition, temperature and pressure. A new model of cladding hydriding is proposed in which calculation of the massive hydride growth is performed in 2-D geometry. Hydrogen transport in zirconium cladding is modeled with account for thermodiffusion. The RTOP code comprising the models developed allows us to calculate different scenarios of hydriding rod failures under given operation conditions. Test calculations were carried out and compared to available data. It is shown that there are threshold values of initial steam content inside the intact fuel rod which lead to the possibility of through-cladding hydride growth and formation of the primary defect. The threshold values depend on the oxidation state of the cladding inner surface, linear power profile in the fuel rod, fuel rod geometry, cladding temperature conditions and hydrogen diffusivities in zirconium and zirconium hydride

  9. Seasonal variation of cesium 134 and cesium 137 in semidomestic reindeer in Norway after the Chernobyl accident

    Directory of Open Access Journals (Sweden)

    I.M. H. Eikelmann

    1990-09-01

    Full Text Available The Chernobyl accident had a great impact on the semidomestic reindeer husbandry in central Norway. Seasonal differences in habitat and diet resulted in large variations in observed radiocesium concentrations in reindeer after the Chernobyl accident. In three areas with high values of cesium-134 and cesium-137 in lichens, the main feed for reindeer in winter, reindeer were sampled every second month to monitor the seasonal variation and the decrease rate of the radioactivity. The results are based on measurements of cesium-134 and cesium-137 content in meat and blood and by whole-body monitoring of live animals. In 1987 the increase of radiocesium content in reindeer in Vågå were 4x from August to January. The mean reductions in radiocesium content from the winter 1986/87 to the winter 1987/88 were 32%, 50% and 43% in the areas of Vågå, Østre-Namdal and Lom respectively.

  10. Hydride distribution around a blister in Zr-2.5Nb pressure tubes

    International Nuclear Information System (INIS)

    Blisters were grown in Zr-2.5Nb pressure tube sections by a thermal gradient without applying external stress. The surrounding hydride distribution was analyzed. Hydride platelets were observed in the radial direction of the blister. The precipitation of these hydrides was found to be favored by low temperature of blister growth and slow cooling rate after blister formation. The misfit strain produced by hydride blister growth provides the stress necessary to promote radial precipitation. During the subsequent tensile test at 200 C (delayed hydride cracking test) the radial hydride length and thickness are increased. This increase is explained by a stress concentrator effect of the blister. When this effect vanishes, the increase of radial hydrides continues by an autocatalytic effect and stress concentrator effect of the hydride platelet. If a crack originated in the blister reaches the matrix it could propagate along a radial hydride previously precipitated. (orig.)

  11. Optimization of Hydride Rim Formation in Unirradiated Zr 4 Cladding

    Energy Technology Data Exchange (ETDEWEB)

    Shimskey, Rick W.; Hanson, Brady D.; MacFarlan, Paul J.

    2013-09-30

    The purpose of this work is to build on the results reported in the M2 milestone M2FT 13PN0805051, document number FCRD-USED-2013-000151 (Hanson, 2013). In that work, it was demonstrated that unirradiated samples of zircaloy-4 cladding could be pre-hydrided at temperatures below 400°C in pure hydrogen gas and that the growth of hydrides on the surface could be controlled by changing the surface condition of the samples and form a desired hydride rim on the outside diameter of the cladding. The work performed at Pacific Northwest National Laboratory since the issuing of the M2 milestone has focused its efforts to optimize the formation of a hydride rim on available zircaloy-4 cladding samples by controlling temperature variation and gas flow control during pre-hydriding treatments. Surface conditioning of the outside surface was also examined as a variable. The results of test indicate that much of the variability in the hydride thickness is due to temperature variation occurring in the furnaces as well as how hydrogen gas flows across the sample surface. Efforts to examine other alloys, gas concentrations, and different surface conditioning plan to be pursed in the next FY as more cladding samples become available

  12. Metal Hydrides for High-Temperature Power Generation

    Directory of Open Access Journals (Sweden)

    Ewa C. E. Rönnebro

    2015-08-01

    Full Text Available Metal hydrides can be utilized for hydrogen storage and for thermal energy storage (TES applications. By using TES with solar technologies, heat can be stored from sun energy to be used later, which enables continuous power generation. We are developing a TES technology based on a dual-bed metal hydride system, which has a high-temperature (HT metal hydride operating reversibly at 600–800 °C to generate heat, as well as a low-temperature (LT hydride near room temperature that is used for hydrogen storage during sun hours until there is the need to produce electricity, such as during night time, a cloudy day or during peak hours. We proceeded from selecting a high-energy density HT-hydride based on performance characterization on gram-sized samples scaled up to kilogram quantities with retained performance. COMSOL Multiphysics was used to make performance predictions for cylindrical hydride beds with varying diameters and thermal conductivities. Based on experimental and modeling results, a ~200-kWh/m3 bench-scale prototype was designed and fabricated, and we demonstrated the ability to meet or exceed all performance targets.

  13. Metal hydrides based high energy density thermal battery

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Zhigang Zak, E-mail: zak.fang@utah.edu [Department of Metallurgical Engineering, The University of Utah, 135 South 1460 East, Room 412, Salt Lake City, UT 84112-0114 (United States); Zhou, Chengshang; Fan, Peng [Department of Metallurgical Engineering, The University of Utah, 135 South 1460 East, Room 412, Salt Lake City, UT 84112-0114 (United States); Udell, Kent S. [Department of Metallurgical Engineering, The University of Utah, 50 S. Central Campus Dr., Room 2110, Salt Lake City, UT 84112-0114 (United States); Bowman, Robert C. [Department of Metallurgical Engineering, The University of Utah, 135 South 1460 East, Room 412, Salt Lake City, UT 84112-0114 (United States); Vajo, John J.; Purewal, Justin J. [HRL Laboratories, LLC, 3011 Malibu Canyon Road, Malibu, CA 90265 (United States); Kekelia, Bidzina [Department of Metallurgical Engineering, The University of Utah, 50 S. Central Campus Dr., Room 2110, Salt Lake City, UT 84112-0114 (United States)

    2015-10-05

    Highlights: • The principle of the thermal battery using advanced metal hydrides was demonstrated. • The thermal battery used MgH{sub 2} and TiMnV as a working pair. • High energy density can be achieved by the use of MgH{sub 2} to store thermal energy. - Abstract: A concept of thermal battery based on advanced metal hydrides was studied for heating and cooling of cabins in electric vehicles. The system utilized a pair of thermodynamically matched metal hydrides as energy storage media. The pair of hydrides that was identified and developed was: (1) catalyzed MgH{sub 2} as the high temperature hydride material, due to its high energy density and enhanced kinetics; and (2) TiV{sub 0.62}Mn{sub 1.5} alloy as the matching low temperature hydride. Further, a proof-of-concept prototype was built and tested, demonstrating the potential of the system as HVAC for transportation vehicles.

  14. U-8 wt %Mo and 7 wt %Mo alloys powder obtained by an hydride-de hydride process

    International Nuclear Information System (INIS)

    Uranium-molybdenum alloys are been tested as a component in high-density LEU dispersion fuels with very good performances. These alloys need to be transformed to powder due to the manufacturing requirements of the fuels. One method to convert ductile alloys into powder is the hydride-de hydride process, which takes advantage of the ability of the U-α phase to transform to UH3: a brittle and relatively low-density compound. U-Mo alloys around 7 and 8 wt % Mo were melted and heat treated at different temperature ranges in order to partially convert γ -phase to α -phase. Subsequent hydriding transforms this α -phase to UH3. The volume change associated to the hydride formation embrittled the material which ends up in a powdered alloy. Results of the optical metallography, scanning electron microscopy, X-ray diffraction during different steps of the process are shown. (author)

  15. Dose mapping experiments of refurbished cesium irradiator

    International Nuclear Information System (INIS)

    Full text: Cesium irradiator is a technology demonstration facility for irradiation of food commodities to achieve various purposes like control of sprouting in onion and potato, insect disinfestations of cereals and pulses, quarantine treatment of fresh fruits and vegetables and shelf life extension of perishable foods. The facility was installed in 1968 and recently refurbished with the new control console. The current source strength (137Cs) of the irradiator is 44.3 kCi. The real success of irradiation of food commodities lies in the adequate delivery of radiation dose to achieve the particular purpose of irradiation. Therefore, evaluation of dose distribution pattern in the product trays of the irradiation facility is of paramount importance. Two sets of dose mapping experiments of the product trays of the facility were carried out to find out the dose distribution profile and dose uniformity ratio. Reference standard dosimeter Fricke was used for the experiment. The standardized ionic concentrations of Fricke dosimeter are Ferrous Ammonium Sulphate (FeSO4(NH4)2SO4 6H2O ) - 1 mM, Sodium Chloride (NaCl) - 1 mM, Sulphuric acid (H2SO4) - 400 mM. The Optical Density (O.D) evaluation was carried out using Spectrophotometry with wave length of 304 nm. The dosimetry tray was partitioned into two planes namely bottom plane and top plane using card-board sheets. Polypropylene vials containing Fricke solution were prepared and fixed on the planes. Each plane was containing nine numbers of dosimeters. The product thickness was around 9 cm. The temperatures of irradiation and measurements were 30 deg C and 28 deg C respectively. The first set of experiment was intended to find out the dose distribution profile throughout the irradiation chamber. The dose rate at Dmin position was observed as 3.69 Gy/min with a poor Dose Uniformity Ratio (DUR) of 6.5. In order to improve the dose rate and DUR the second set of the experiment was carried out with modified product geometry

  16. A quantitative phase field model for hydride precipitation in zirconium alloys: Part II. Modeling of temperature dependent hydride precipitation

    International Nuclear Information System (INIS)

    A quantitative free energy functional developed in Part I (Shi and Xiao, 2014 [1]) was applied to model temperature dependent δ-hydride precipitation in zirconium in real time and real length scale. At first, the effect of external tensile load on reorientation of δ-hydrides was calibrated against experimental observations, which provides a modification factor for the strain energy in free energy formulation. Then, two types of temperature-related problems were investigated. In the first type, the effect of temperature transient was studied by cooling the Zr–H system at different cooling rates from high temperature while an external tensile stress was maintained. At the end of temperature transients, the average hydride size as a function of cooling rate was compared to experimental data. In the second type, the effect of temperature gradients was studied in a one or two dimensional temperature field. Different boundary conditions were applied. The results show that the hydride precipitation concentrated in low temperature regions and that it eventually led to the formation of hydride blisters in zirconium. A brief discussion on how to implement the hysteresis of hydrogen solid solubility on hydride precipitation and dissolution in the developed phase field scheme is also presented

  17. Improvement of cesium retention in uranium dioxide by additional phases

    International Nuclear Information System (INIS)

    The objective of this study is to improve the cesium retention in nuclear fuel. A bibliographic survey indicates that cesium is rapidly released from uranium dioxide in an accident condition. At temperatures higher than 1500 deg C or in oxidising conditions, our experiments show the difficulty of maintaining cesium inside simulated fuel. Two ternary systems are potentially interesting for the retention of cesium and to reduce the kinetics of release from the fuel: Cs2O-Al2O3-SiO2 et Cs2O-ZrO2-SO2. The compounds CsAISi2O6 and Cs2ZrSi6O15 were studied from 1200 deg C to 2000 deg C by thermogravimetric analysis. The volumetric diffusion coefficients of cesium in these structures, in solid state as well as in liquid one, were measured. A fuel was sintered with (Al2O3 + SiO2) or (ZrO2 + SiO2) and the intergranular phase was characterized. In the presence of (Al2O3 + SiO2), the sintering is realized at 1610 deg C in H2. It is a liquid phase sintering. On the other end, with (ZrO2 + SiO2), the sintering is a low temperature one in oxidising atmosphere. Finally, cesium containing simulated fuels were produced with these additives. According to the effective diffusion coefficients that were measured, the additives improved the retention of cesium. We have predicted the improvement that could be hoped for in a nuclear reactor, depending on the dispersion of the intergranular additives, the temperature and the degree of oxidation of the UO2+x. We wait for a factor of 2 for x=0 and more than 8 for x=0.05, up to 2000 deg C. (author). 148 refs., 122 figs., 34 tabs

  18. Hydriding and dehydriding characteristics of LiBH4 and transition metals-added magnesium hydride

    International Nuclear Information System (INIS)

    Graphical abstract: Hydriding reaction curves under 12 bar H2, and dehydriding reaction curves under 1.0 bar H2, at 593 K at the 1st cycle for MgH2–10Ni–2LiBH4–2Ti and MgH2. Highlights: ► Addition of Ni, LiBH4, and Ti to MgH2 to increase reaction rates. ► Sample preparation by reactive mechanical grinding. ► At n = 2, the sample absorbed 4.05 wt% H for 60 min at 593 K under 12 bar H2. ► Analysis of rate-controlling step for dehydriding of the sample at n = 3. - Abstract: In this study, MgH2 was used as a starting material instead of Mg. Ni, Ti, and LiBH4 with a high hydrogen-storage capacity of 18.4 wt% were added. A sample with a composition of MgH2–10Ni–2LiBH4–2Ti was prepared by reactive mechanical grinding. The activation of MgH2–10Ni–2LiBH4–2Ti was completed after the first hydriding–dehydrding cycle. The hydriding rate decreases as the temperature increases due to the decrease in the driving force for the hydriding reaction. At the 1st cycle, the sample desorbs 1.45 wt% H for 10 min, 2.54 wt% H for 20 min, 3.13 wt% H for 30 min, and 3.40 wt% H for 60 min at 593 K under 1.0 bar H2. At the 2nd cycle, the sample absorbs 3.84 wt% H for 5 min, 3.96 wt% H for 10 min, and 4.05 wt% H for 60 min at 593 K under 12 bar H2. MgH2–10Ni–2LiBH4–2Ti after reactive mechanical grinding contained MgH2, Mg, Ni, TiH1.924, and MgO phases. The reactive mechanical grinding of Mg with Ni, LiBH4, and Ti is considered to create defects on the surface and in the interior of Mg (to facilitate nucleation), and to reduce the particle size of Mg (to shorten diffusion distances of hydrogen atoms). The formation of Mg2Ni during hydriding–dehydriding cycling increases the hydriding and dehydriding rates of the sample

  19. Chemical Hydride Slurry for Hydrogen Production and Storage

    Energy Technology Data Exchange (ETDEWEB)

    McClaine, Andrew W

    2008-09-30

    The purpose of this project was to investigate and evaluate the attractiveness of using a magnesium chemical hydride slurry as a hydrogen storage, delivery, and production medium for automobiles. To fully evaluate the potential for magnesium hydride slurry to act as a carrier of hydrogen, potential slurry compositions, potential hydrogen release techniques, and the processes (and their costs) that will be used to recycle the byproducts back to a high hydrogen content slurry were evaluated. A 75% MgH2 slurry was demonstrated, which was just short of the 76% goal. This slurry is pumpable and storable for months at a time at room temperature and pressure conditions and it has the consistency of paint. Two techniques were demonstrated for reacting the slurry with water to release hydrogen. The first technique was a continuous mixing process that was tested for several hours at a time and demonstrated operation without external heat addition. Further work will be required to reduce this design to a reliable, robust system. The second technique was a semi-continuous process. It was demonstrated on a 2 kWh scale. This system operated continuously and reliably for hours at a time, including starts and stops. This process could be readily reduced to practice for commercial applications. The processes and costs associated with recycling the byproducts of the water/slurry reaction were also evaluated. This included recovering and recycling the oils of the slurry, reforming the magnesium hydroxide and magnesium oxide byproduct to magnesium metal, hydriding the magnesium metal with hydrogen to form magnesium hydride, and preparing the slurry. We found that the SOM process, under development by Boston University, offers the lowest cost alternative for producing and recycling the slurry. Using the H2A framework, a total cost of production, delivery, and distribution of $4.50/kg of hydrogen delivered or $4.50/gge was determined. Experiments performed at Boston

  20. Cesium and strontium in Black Sea macroalgae

    International Nuclear Information System (INIS)

    The trace level of metals and particularly radioactive ones should be monitored to evaluate the transfer along the trophic chain, assess the risk for biota and can be used for global changes assessment. Plants respond rapidly to all changes in the ecosystem conditions and are widely used as indicators and predictors for changes in hydrology and geology. In this work we represent our successful development and applications of a methodology for monitoring of stable and radioactive strontium and cesium in marine biota (Black Sea algae's). In case of radioactive release they are of high interest. We use ED-XRF, gamma spectrometers and LSC instrumentation and only 0.25 g sample. Obtained results are compared with those of other authors in same regions. The novelty is the connection between the radioactive isotopes and their stable elements in algae in time and space scale. All our samples were collected from Bulgarian Black Sea coast. - Highlights: • An extraction chromatography method for radiochemical separation of Sr and Cs. • Assessment of Sr and Cs accumulation capacity of six Black Sea macroalgae species. • Connection between the isotopes and their stable elements content in algae. • Assessment of Sr and Cs content in ecosystems along the Bulgarian coast

  1. Cesium-137 levels detected in Georgia otters

    International Nuclear Information System (INIS)

    Beginning in the 1940's and continuing through the 50's and early 60's, nuclear devices were tested by aerial detonation in the United States and other countries around the world. Cesium-137 (137Cs) is one of the most important radionuclide by-products due to its abundance and slow decay (30-year half-life). The uptake of 137Cs in animal tissue is the result of its similarity to potassium. The somatic and genetic effects of 137Cs, along with its effect on reproductive cells, can pose great hazards to wildlife species. A reported buildup of 137Cs in white-tailed deer in the lower coastal plain of Georgia during the 1960's was followed by a gradual decline during the 1970's. Although numerous studies have involved terrestrial mammals of Georgia, few have involved aquatic mammals such as the river otter. With continued atmospheric testing by some foreign countries and the increased use of nuclear power as an energy source, there is a need for continued monitoring of radionuclides in wildlife to ascertain the quality of the environment. This study was initiated as part of an overall study of environmental pollutants in the river otter of Georgia and deals with analysis of the 137Cs accumulations in this species

  2. Simultaneous Heat and Mass Transfer in DU Hydriding

    International Nuclear Information System (INIS)

    The sources of nuclear fusion reaction are deuterium (D) and tritium (T). Generally, D is fused into T, which generates helium atoms and neutrons. At this time, a tremendous amount of energy is generated. D + T → 4He + n (E = 17.6 MeV) Hydrogen is a gas, and cannot be stored in large amounts. In addition, it can be explosive. Therefore, one of the storing methods for hydrogen is metal hydride. In this research, several kinds of metal hydrides including U, Zr, ZrCo, ZrNi, and LaNi5 have been simulated through modeling work of hydrogen absorption, desorption, and pressure effect in a bed using DU. For the exact modeling of the hydriding process, it is necessary to calculate simultaneous heat and mass transfer because, in the hydriding process, not only is hydrogen gas transported by mass transport and chemisorption but heat transfer also occurs through absorption. Therefore, in this paper, we tried to calculate the simultaneous heat and mass transfer using numerical analysis methods. Simultaneous heat and mass transfer in DU hydriding is well fitted compared to the experimental data, and is more reasonable considering only one variable. The hydriding process changes the temperature and atomic ratio simultaneously, and thus it is necessary to consider in company with two transport phenomena. The numerical analysis method applied Euler's method; however, the Runge-Kutta method is a more widely used numerical solution of a differential equation. Therefore, when analyzing the hydriding process, Runge-Kutta or another method will henceforth be applied

  3. Influence of uranium hydride oxidation on uranium metal behaviour

    International Nuclear Information System (INIS)

    This work addresses concerns that the rapid, exothermic oxidation of active uranium hydride in air could stimulate an exothermic reaction (burning) involving any adjacent uranium metal, so as to increase the potential hazard arising from a hydride reaction. The effect of the thermal reaction of active uranium hydride, especially in contact with uranium metal, does not increase in proportion with hydride mass, particularly when considering large quantities of hydride. Whether uranium metal continues to burn in the long term is a function of the uranium metal and its surroundings. The source of the initial heat input to the uranium, if sufficient to cause ignition, is not important. Sustained burning of uranium requires the rate of heat generation to be sufficient to offset the total rate of heat loss so as to maintain an elevated temperature. For dense uranium, this is very difficult to achieve in naturally occurring circumstances. Areas of the uranium surface can lose heat but not generate heat. Heat can be lost by conduction, through contact with other materials, and by convection and radiation, e.g. from areas where the uranium surface is covered with a layer of oxidised material, such as burned-out hydride or from fuel cladding. These rates of heat loss are highly significant in relation to the rate of heat generation by sustained oxidation of uranium in air. Finite volume modelling has been used to examine the behaviour of a magnesium-clad uranium metal fuel element within a bottle surrounded by other un-bottled fuel elements. In the event that the bottle is breached, suddenly, in air, it can be concluded that the bulk uranium metal oxidation reaction will not reach a self-sustaining level and the mass of uranium oxidised will likely to be small in relation to mass of uranium hydride oxidised. (authors)

  4. Uptake of cesium ions by human erythrocytes and perfused rat heart: a cesium-133 NMR study

    Energy Technology Data Exchange (ETDEWEB)

    Davis, D.G.; Murphy, E.; London, R.E.

    1988-05-17

    Cesium-133 NMR studies have been carried out on suspended human erythrocytes and on perfused rat hearts in media containing CsCl. The resulting spectra exhibit two sharp resonances, arising from intra-and extracellular Cs/sup +/, separated in chemical shift by 1.0-1.4 ppm. Thus, intra- and extracellular resonances are easily resolved without the addition of paramagnetic shift reagents required to resolve resonance of the other alkali metal ions. Spin-lattice relaxation times in all cases are monoexponential and significantly shorter (3-4 times) for the intracellular component. When corrections are made for the pulse repetition rate, the total intensity of the intracellular and extracellular Cs/sup +/ resonances in erythrocytes is conserve, implying total observability of the intracellular pool. The uptake of Cs/sup +/ by erythrocytes occurs at approximately one-third the reported rate for K/sup +/ and was reduced by a factor of 2 upon addition of ouabain to the sample. These results indicate that /sup 133/Cs NMR is a promising tool for studying the distribution and transport of cesium ions in biological systems and, in some cases such as uptake by cellular Na,K-ATPase, for analysis of K/sup +/ ion metabolism.

  5. Hydriding and neutron irradiation in zircaloy-4

    International Nuclear Information System (INIS)

    The composition of Zircaloy-4 for nuclear applications is specified by the ASTM B350 Standard, that fixes the amount of alloying elements (Sn, Fe, Cr) and impurities (Ni, Hf, O, N, C, among others) to optimize good corrosion and mechanical behavior.The recycling of zircaloy-4 scrap and chips resulting from cladding tube fabrication is an interesting issue.However, changes in the final composition of the recycled material may occur due to contamination with tool pieces, stainless steel chips, turnings, etc. while scrap is stored and handled. Since the main components of the possible contaminants are Fe, Cr and Ni, it arises the interest in studying up to what limit the Fe, Ni and Cr contents could be exceeded beyond the standard specification without affecting significantly the alloy properties.Zircaloy-4 alloys elaborated with Fe, Cr and Ni additions and others of standard composition in use in nuclear plants are studied by tensile tests, SEM observations and EDS microanalysis.Some samples are tested in the initial condition and others after hydriding treatments and neutron irradiation in the RA6

  6. Reactions of NO with nitrogen hydrides x

    Science.gov (United States)

    Mebel, A. M.; Lin, M. C.

    In this review, we consider the reactions of NO ( x 1,2) with the nitrogen x hydrides NH, NH and NH . The reactions are relevant to the post-combustion, non-catalytic reduction of NO with NH in the thermal de-NO process and with x x HNCO in the rapid reduction of NO as well as to the thermal decomposition of x some high-energy materials, including ammonium dinitramide. The practical importance has motivated considerable theoretical interest in these reactions. We review numerous ab - initio molecular orbital studies of potential energy surfaces for NO NH and theoretical calculations of their kinetic parameters, such as x y thermal rate constants and branching ratios of various products. The most advanced theoretical calculations are carried out using the Gaussian-2 family of methods which provides the chemical accuracy (within 2 kcal mol ) for the energetics and molecular parameters of the reactants, products, intermediates and transition states. We present a detailed comparison of the theoretical results with available experimental data. We show that the reactions of NO with NH and NH x are very fast because they occur without a barrier and lead to the formation of multiple products which include radicals and stable molecules. The reactions of NO with NH , taking place by the H abstraction to form NH and HNO , are slow x x but still relevant to the NH de-NO system, because of their fast reverse processes x which have not yet been measured experimentally.

  7. Micro-PIXE evaluation of radioactive cesium transfer in contaminated soil samples

    International Nuclear Information System (INIS)

    Highlights: • There are radioactively contaminated soils having a radioactive cesium transfer of 0.01. • Micro-PIXE analysis has revealed an existence of phosphorus in a contaminated soil. • Radioactive cesium captured by phosphorus compound would be due to radioactive transfer. -- Abstract: Micro-PIXE analysis has been performed on two soil samples with high cesium activity concentrations. These soil samples were contaminated by fallout from the accident at Fukushima Daiichi Nuclear Power Plant. One exhibits a radioactive cesium transfer of ∼0.01, and the other shows a radioactive cesium transfer of less than 0.001, even though both samples have high cesium activity concentrations exceeding 10,000 Bq/kg. X-ray spectra and elemental images of the soil samples revealed the presence of chlorine, which can react with cesium to produce an inorganic soluble compound, and phosphorus-containing cesium-capturable organic compounds

  8. A fundamental study on cesium migration to sodium at low temperature

    International Nuclear Information System (INIS)

    Our experiment study aims to understand the behavior of cesium in severe accident of sodium cooled fast breeder reactor, especially cesium migration rate to sodium. In past study, exact migration rate of cesium to sodium has not been reported because of difficulty of the cesium-sodium interfacial area evaluations of gas bubble. In this study, we developed a pool-type experimental apparatus which can simplify the shape of interfacial area, and measured cesium migration rate in a low temperature range of 200degC to 300degC. The cesium migration rates obtained under the condition that the cesium mixed argon gas flow is the same temperature with sodium vary in the range of 10-3 - 10-1 mol/m2min and increase with increasing the system temperature. The difference of cesium migration rates between non-oxidized sodium surface and oxidized sodium surface is also clearly observed. (author)

  9. Viscosity and crystallization mechanism of cesium loaded iron phosphate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Joseph, Kitheri, E-mail: joskit@igcar.gov.in [Chemistry Group, IGCAR, Kalpakkam 603 102 (India); Kutty, K.V. Govindan [Chemistry Group, IGCAR, Kalpakkam 603 102 (India); Goswami, M.C. [National Metallurgical Laboratory, Jamshedpur 831 007 (India); Rao, P.R. Vasudeva [Chemistry Group, IGCAR, Kalpakkam 603 102 (India)

    2014-07-01

    Highlights: • Melt viscosity of cesium loaded iron phosphate glasses is measured and reported for the first time. • Viscosity – temperature followed Arrhenius model. • Activation energy of viscous flow is strongly correlated to glass transition temperature of the glasses. • Process of crystallization of cesium loaded glass by approximation-free kinetic method to understand the mechanism. • Cesium loaded IPG and IPG shows bulk crystallization mechanism. - Abstract: This paper describes the melt viscosity behaviour and the crystallization mechanism of a series of iron phosphate glasses. High temperature viscosity measurements were carried out on pristine iron phosphate glass and a series of cesium loaded iron phosphate glasses in order to understand the effect of addition of Cs{sub 2}O on viscosity of iron phosphate glasses. Activation energy of viscous flow was estimated from the experimental data by applying Arrhenius model of viscosity–temperature relationship. Activation energy of viscous flow is observed to be strongly correlated to glass transition temperature of these glasses. Fragility of iron phosphate and cesium loaded iron phosphate glass systems were also evaluated in region of high temperature. Crystallization of these glasses was studied using thermal analysis techniques. Temperature integral approximation free method was utilized to evaluate the kinetic parameters such as activation energy of crystallization (E{sub c}) and Avrami exponent (n). The value of Avrami exponent ‘n’ obtained showed that the glasses under present study crystallize via bulk crystallization mechanism, i.e., nucleation and three dimensional growth.

  10. Cesium corrosion process in Fe–Cr steel

    International Nuclear Information System (INIS)

    A cesium corrosion out-pile test was performed to Fe–Cr steel in a simulated fuel pin environment. In order to specify the corrosion products, the corroded area was analyzed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). A cesium corrosion process in Fe–Cr steel was successfully developed proceeding from both experimental results and thermochemical consideration. The corroded area was mainly formed by Fe layer and Fe depleted oxidized layer. The Fe depleted oxidized layer was formed by Cr0.5Fe0.5 and Cr2O3. The presumed main corrosion reactions were 2Cr+2/3 O2→Cr2O3(ΔG650°C=-894.1kJ/mol) and Cr23C6+46Cs+46O2→23Cs2CrO4+6C(ΔG650°C=-25018.1kJ/mol). Factors of these reactions are chromium, carbon, oxygen and cesium. Therefore, cesium corrosion progression must be dependent on the chromium content, carbon content in the steel, the supply rate of oxygen and temperature which correlated with the diffusion rate of cesium and oxygen into the specimen

  11. Viscosity and crystallization mechanism of cesium loaded iron phosphate glasses

    International Nuclear Information System (INIS)

    Highlights: • Melt viscosity of cesium loaded iron phosphate glasses is measured and reported for the first time. • Viscosity – temperature followed Arrhenius model. • Activation energy of viscous flow is strongly correlated to glass transition temperature of the glasses. • Process of crystallization of cesium loaded glass by approximation-free kinetic method to understand the mechanism. • Cesium loaded IPG and IPG shows bulk crystallization mechanism. - Abstract: This paper describes the melt viscosity behaviour and the crystallization mechanism of a series of iron phosphate glasses. High temperature viscosity measurements were carried out on pristine iron phosphate glass and a series of cesium loaded iron phosphate glasses in order to understand the effect of addition of Cs2O on viscosity of iron phosphate glasses. Activation energy of viscous flow was estimated from the experimental data by applying Arrhenius model of viscosity–temperature relationship. Activation energy of viscous flow is observed to be strongly correlated to glass transition temperature of these glasses. Fragility of iron phosphate and cesium loaded iron phosphate glass systems were also evaluated in region of high temperature. Crystallization of these glasses was studied using thermal analysis techniques. Temperature integral approximation free method was utilized to evaluate the kinetic parameters such as activation energy of crystallization (Ec) and Avrami exponent (n). The value of Avrami exponent ‘n’ obtained showed that the glasses under present study crystallize via bulk crystallization mechanism, i.e., nucleation and three dimensional growth

  12. The diffusion of cesium, strontium, and europium in silicon carbide

    Science.gov (United States)

    Dwaraknath, S. S.; Was, G. S.

    2016-08-01

    A novel multi-layer diffusion couple was used to isolate the diffusion of strontium, europium and cesium in SiC without introducing radiation damage to SiC and at concentrations below the solubility limit for the fission products in SiC. Diffusion occurred by both bulk and grain boundary pathways for all three fission products between 900∘ C and 1 ,300∘ C. Cesium was the fastest diffuser below 1 ,100∘ C and the slowest above this temperature. Strontium and europium diffusion tracked very closely as a function of temperature for both bulk and grain boundary diffusion. Migration energies ranged from 1.0 eV to 5.7 eV for bulk diffusion and between 2.2 eV and 4.7 eV for grain boundary diffusion. These constitute the first measurements of diffusion of cesium, europium, and strontium in silicon carbide, and the magnitude of the cesium diffusion coefficient supports the premise that high quality TRISO fuel should have minimal cesium release.

  13. Micro-scale fracture experiments on zirconium hydrides and phase boundaries

    Science.gov (United States)

    Chan, H.; Roberts, S. G.; Gong, J.

    2016-07-01

    Fracture properties of micro-scale zirconium hydrides and phase boundaries were studied using microcantilever testing methods. FIB-machined microcantilevers were milled on cross-sectional surfaces of hydrided samples, with the most highly-stressed regions within the δ-hydride film, within the α-Zr or along the Zr-hydride interface. Cantilevers were notched using the FIB and then tested in bending using a nanoindenter. Load-displacement results show that three types of cantilevers have distinct deformation properties. Zr cantilevers deformed plastically. Hydride cantilevers fractured after a small amount of plastic flow; the fracture toughness of the δ-hydride was found to be 3.3 ± 0.4 MPam1/2 and SEM examination showed transgranular cleavage on the fracture surfaces. Cantilevers notched at the Zr-hydride interface developed interfacial voids during loading, at loads considerably lower than that which initiate brittle fracture of hydrides.

  14. Numerical simulation and performance test of metal hydride hydrogen storage system

    Directory of Open Access Journals (Sweden)

    Tzu-Hsiang Yen, Bin-Hao Chen, Bao-Dong Chen

    2011-05-01

    Full Text Available Metal hydride reactors are widely used in many industrial applications, such as hydrogen storage, thermal compression, heat pump, etc. According to the research requirement of metal hydride hydrogen storage, the thermal analyses have been implemented in the paper. The metal hydride reaction beds are considered as coupled cylindrical tube modules which combine the chemical absorption and desorption in metal hydride. The model is then used metal hydride LaNi5 as an example to predict the performance of metal hydride hydrogen storage devices, such as the position of hydration front and the thermal flux. Under the different boundary condition the characteristics of heat transfer and mass transfer in metal hydride have influence on the hydrogen absorption and desorption. The researches revealed that the scroll design can improve the temperature distribution in the reactor and the porous tube for directing hydrogen can increase the penetration depth of hydride reaction to decrease the hydrogen absorption time.

  15. Dissociative excitation of cesium atom upon e-CsOH collisions

    International Nuclear Information System (INIS)

    The process of dissociative excitation of cesium atom in collisions with mono-kinetic molecules of cesium hydroxide is studied. It is established that behaviour of dissociative excitations the cesium atom in spectral series corresponds of to the grade dependence of cross sections on the main quantum number of the upper level. The values of constants, characterizing the behaviour of cross sections in the eight spectral series of the cesium atom are determined

  16. Sodium-based hydrides for thermal energy applications

    Science.gov (United States)

    Sheppard, D. A.; Humphries, T. D.; Buckley, C. E.

    2016-04-01

    Concentrating solar-thermal power (CSP) with thermal energy storage (TES) represents an attractive alternative to conventional fossil fuels for base-load power generation. Sodium alanate (NaAlH4) is a well-known sodium-based complex metal hydride but, more recently, high-temperature sodium-based complex metal hydrides have been considered for TES. This review considers the current state of the art for NaH, NaMgH3- x F x , Na-based transition metal hydrides, NaBH4 and Na3AlH6 for TES and heat pumping applications. These metal hydrides have a number of advantages over other classes of heat storage materials such as high thermal energy storage capacity, low volume, relatively low cost and a wide range of operating temperatures (100 °C to more than 650 °C). Potential safety issues associated with the use of high-temperature sodium-based hydrides are also addressed.

  17. Influence of Specific Surface Area of Powder on Hydrogen Desorption Kinetics for Metal Hydrides

    CERN Document Server

    Drozdov, I V

    2014-01-01

    The observable results for desorption kinetics by powder of metal hydride on the example of mangesium hydride are reproduced with the model formulated in terms of specific surface of powder. A volumetric measurement of hydrogen desorption process is evaluated on an example of wet ball milled magnesium hydride, and can be applied generally for any metal hydride. The exact solution of the model reproduces the shape of experimental curves for desorption process providing a satisfying agreement with experimental data.

  18. Sorption of cesium and uranium to Feldspar

    International Nuclear Information System (INIS)

    Within safety assessment studies, for nuclear waste disposal in deep geologic formations, calculation for the migration of radionuclides through the geosphere are often carried out with models taking sorption into account. In the past 8 years the insight grew that other physico-chemical processes, besides sorption, could affect migration behaviour. While the currently used transport models were being improved taking either linear or non-linear sorption into account, the coupling of geochemical and transport models came into scope. In spite of these developments models which are still based on the sorption theory are frequently applied in studying migration behaviour of radionuclides. This is caused by the necessity of making preliminary pronouncements, while coupled models are still in stage of development and thermodynamic data are very limited available. Therefore one has to obtain insight in the reliability of the models based on the sorption theory. within the sorption database there is a lack of knowledge about mineralogy, composition of the fluid and the experimental conditions underlying the data. Therefore the Expert Group on geochemical Modelling supported by the Finnish proposal in order to obtain insight in the possible deviation of the sorption coefficients that can be estimated from experiments performed with standard samples, fluid composition and experimental conditions. Nine laboratories from OECD membership countries took part in this intercalibration study. In the framework of the Dutch safety assessment studies the Dutch National Institute of Public health and Environmental protection (RIVM) has decided to participate in this exercise. In this report the results are presented of sorption experiments for cesium and natural Uranium to Feldspar. (H.W.). 4 refs.; 1 fig.; 7 tabs

  19. Cesium in the Savannah River Site environment

    International Nuclear Information System (INIS)

    Cesium in the Savannah River Site Environment is published as a part of the Radiological Assessment Program (RAP). It is the fourth in a series of eight documents on individual radioisotopes released to the environment as a result of Savannah River Site (SRS) operations. The earlier documents describe the environmental consequences of tritium, iodine, and uranium. Documents on plutonium, strontium, carbon, and technetium will be published in the future. These are dynamic documents and current plans call for revising and updating each one on a two-year schedule.Radiocesium exists in the environment as a result of above-ground nuclear weapons tests, the Chernobyl accident, the destruction of satellite Cosmos 954, small releases from reactors and reprocessing plants, and the operation of industrial, medical, and educational facilities. Radiocesium has been produced at SRS during the operation of five production reactors. Several hundred curies of 137Cs was released into streams in the late 50s and 60s from leaking fuel elements. Smaller quantities were released from the fuel reprocessing operations. About 1400 Ci of 137Cs was released to seepage basins where it was tightly bound by clay in the soil. A much smaller quantity, about four Ci. was released to the atmosphere. Radiocesium concentration and mechanisms for atmospheric, surface water, and groundwater have been extensively studied by Savannah River Technology Center (SRTC) and ecological mechanisms have been studied by Savannah River Ecology Laboratory (SREL). The overall radiological impact of SRS releases on the offsite maximum individual can be characterized by total doses of 033 mrem (atmospheric) and 60 mrem (liquid), compared with a dose of 12,960 mrem from non-SRS sources during the same period of time. Isotope 137Cs releases have resulted in a negligible risk to the environment and the population it supports

  20. Cesium in the Savannah River Site environment

    Energy Technology Data Exchange (ETDEWEB)

    Carlton, W.H.; Bauer, L.R.; Evans, A.G.; Geary, L.A.; Murphy, C.E. Jr.; Pinder, J.E.; Strom, R.N.

    1992-03-01

    Cesium in the Savannah River Site Environment is published as a part of the Radiological Assessment Program (RAP). It is the fourth in a series of eight documents on individual radioisotopes released to the environment as a result of Savannah River Site (SRS) operations. The earlier documents describe the environmental consequences of tritium, iodine, and uranium. Documents on plutonium, strontium, carbon, and technetium will be published in the future. These are dynamic documents and current plans call for revising and updating each one on a two-year schedule.Radiocesium exists in the environment as a result of above-ground nuclear weapons tests, the Chernobyl accident, the destruction of satellite Cosmos 954, small releases from reactors and reprocessing plants, and the operation of industrial, medical, and educational facilities. Radiocesium has been produced at SRS during the operation of five production reactors. Several hundred curies of {sup 137}Cs was released into streams in the late 50s and 60s from leaking fuel elements. Smaller quantities were released from the fuel reprocessing operations. About 1400 Ci of {sup 137}Cs was released to seepage basins where it was tightly bound by clay in the soil. A much smaller quantity, about four Ci. was released to the atmosphere. Radiocesium concentration and mechanisms for atmospheric, surface water, and groundwater have been extensively studied by Savannah River Technology Center (SRTC) and ecological mechanisms have been studied by Savannah River Ecology Laboratory (SREL). The overall radiological impact of SRS releases on the offsite maximum individual can be characterized by total doses of 033 mrem (atmospheric) and 60 mrem (liquid), compared with a dose of 12,960 mrem from non-SRS sources during the same period of time. Isotope {sup 137}Cs releases have resulted in a negligible risk to the environment and the population it supports.

  1. Cesium in the Savannah River Site environment

    Energy Technology Data Exchange (ETDEWEB)

    Carlton, W.H.; Bauer, L.R.; Evans, A.G.; Geary, L.A.; Murphy, C.E. Jr.; Pinder, J.E.; Strom, R.N.

    1992-03-01

    Cesium in the Savannah River Site Environment is published as a part of the Radiological Assessment Program (RAP). It is the fourth in a series of eight documents on individual radioisotopes released to the environment as a result of Savannah River Site (SRS) operations. The earlier documents describe the environmental consequences of tritium, iodine, and uranium. Documents on plutonium, strontium, carbon, and technetium will be published in the future. These are dynamic documents and current plans call for revising and updating each one on a two-year schedule.Radiocesium exists in the environment as a result of above-ground nuclear weapons tests, the Chernobyl accident, the destruction of satellite Cosmos 954, small releases from reactors and reprocessing plants, and the operation of industrial, medical, and educational facilities. Radiocesium has been produced at SRS during the operation of five production reactors. Several hundred curies of [sup 137]Cs was released into streams in the late 50s and 60s from leaking fuel elements. Smaller quantities were released from the fuel reprocessing operations. About 1400 Ci of [sup 137]Cs was released to seepage basins where it was tightly bound by clay in the soil. A much smaller quantity, about four Ci. was released to the atmosphere. Radiocesium concentration and mechanisms for atmospheric, surface water, and groundwater have been extensively studied by Savannah River Technology Center (SRTC) and ecological mechanisms have been studied by Savannah River Ecology Laboratory (SREL). The overall radiological impact of SRS releases on the offsite maximum individual can be characterized by total doses of 033 mrem (atmospheric) and 60 mrem (liquid), compared with a dose of 12,960 mrem from non-SRS sources during the same period of time. Isotope [sup 137]Cs releases have resulted in a negligible risk to the environment and the population it supports.

  2. Spins and magnetic moments of rubidium and cesium nuclides far from stability

    International Nuclear Information System (INIS)

    Previous studies at ISOLDE have concerned spins and magnetic moments of neutron-deficient rubidium and cesium isotopes. Here, the main results obtained, and, in the case of cesium, new moment measurements are briefly discussed also the results from measurements on neutron-rich nuclides of rubidium and cesium. (orig./AH)

  3. Environmental application of cesium-137 irradiation technology: Sludges and foods

    Science.gov (United States)

    Sivinski, Jacek S.

    Several activities have been undertaken to investigate and implement the use of the military byproduct cesium-137 in ways which benefit mankind. Gamma radiation from cesium-137 has been shown to be effective in reducing pathogens in sewage sludge to levels where reuse of the material in public areas meets current regulatory criteria for protection of public health. Food irradiation at doses of 10 kGy or less have been found by international expert committees to be wholesome and safe for human consumption. Cesium-137 can be used as a means of enhancing particular properties of various food commodities by means of sterilization, insect disinfestation, delayed senescence and ripening, and sprout inhibition. This paper discusses the U.S. Department of Energy Beneficial Uses Program research and engineering history, as well as current activities and future plans, relating to both sewage sludge and food irradiation.

  4. Environmental application of cesium-137 irradiation technology: sludges and foods

    International Nuclear Information System (INIS)

    Several activities have been undertaken to investigate and implement the use of the military byproduct cesium-137 in ways which benefit mankind. Gamma radiation from cesium-137 has been shown to be effective in reducing pathogens in sewage sludge to levels where reuse of the material in public areas meets current regulatory criteria for protection of public health. Food irradiation at doses of 10 kGy or less have been found by international expert committees to be wholesome and safe for human consumption. Cesium-137 can be used as a means of enhancing particular properties of various food commodities by means of sterilization, insect disinfestation, delayed senescence and ripening, and sprout inhibition. This paper discusses the U.S. Department of Energy Beneficial Uses Program research and engineering history, as well as current activities and future plans, relating to both sewage sludge and food irradiation. (author)

  5. Dating of mine waste in lacustrine sediments using cesium-137

    Science.gov (United States)

    Rember, W. C.; Erdman, T. W.; Hoffmann, M. L.; Chamberlain, V. E.; Sprenke, K. F.

    1993-11-01

    For over a century Medicine Lake in northern Idaho has received heavy-metal-laden tailings from the Coeur d'Alene mining district. Establishing the depositional chronology of the lake bottom sediments provides information on the source and rate of deposition of the tailings. Cesium-137, an isotope produced in the atmosphere by nuclear bomb tests, was virtually absent in the environment prior to 1951, but reached its apex in 1964. Our analysis of cesium-137 in the sediments of Medicine Lake revealed that 14 cm of fine-grained tailings were deposited in the lake from 1951 to 1964 and tailing deposition downstream was greatly reduced by the installation of tailings dams in the district in 1968. Cesium-137 analysis is accomplished by a fairly simple gamma-ray counting technique and should be a valuable tool for analyzing sedimentation in any lacustrine environment that was active during the 1950s and 1960s.

  6. Cesium 137 in oils and plants from Guatemala

    International Nuclear Information System (INIS)

    Since 1990 the project of radioactive and environmental contamination started in Guatemala. Studies about the radioactive contamination levels are made within the framework of this project. Cesium-137 has been an interest radionuclide, because it is a fission product released to the environment by the use of nuclear weapons and nuclear power plants accidents. The sampling consisted in collection of soil and grass in 20 provinces of Guatemala, one point by province, and it was made in 1990. The cesium-137 concentration in the samples, was determined by gamma spectrometry, using an hyper pure germanium detector. The results show the presence of radioactive contamination in soil and grass due to cesium-137, at levels that might be considered as normal. The levels found are not harmful for human health, and its importance is the fact that can be used as reference levels for the environmental radioactivity monitoring in Guatemala

  7. Study of radiatively sustained cesium plasmas for solar energy conversion

    Science.gov (United States)

    Palmer, A. J.; Dunning, G. J.

    1980-01-01

    The results of a study aimed at developing a high temperature solar electric converter are reported. The converter concept is based on the use of an alkali plasma to serve as both an efficient high temperature collector of solar radiation as well as the working fluid for a high temperature working cycle. The working cycle is a simple magnetohydrodynamic (MHD) Rankine cycle employing a solid electrode Faraday MHD channel. Research milestones include the construction of a theoretical model for coupling sunlight in a cesium plasma and the experimental demonstration of cesium plasma heating with a solar simulator in excellent agreement with the theory. Analysis of a solar MHD working cycle in which excimer laser power rather than electric power is extracted is also presented. The analysis predicts a positive gain coefficient on the cesium-xenon excimer laser transition.

  8. On the compartmental modeling of cesium migration in soils

    International Nuclear Information System (INIS)

    The prediction of the migration of radionuclides in soil following deposition after a nuclear accident is important for both external dose and plant uptake prediction. In this paper, the validity conditions of compartment models for cesium migration in soils are investigated. A compartment model is derived from a diffusion-convection model. The model considers free and bound cesium compartments and is applied to measured profiles of 137Cs of undisturbed soil in Northern Greece. It is concluded that the rate of cesium transfer must vary linearly with depth and that from measured equilibrium profiles, the ratios of model parameters can be determined but not the parameters themselves. This model is applied to measured profiles of 137Cs in soil due to wet deposition following the Chernobyl accident

  9. A study of advanced magnesium-based hydride and development of a metal hydride thermal battery system

    Science.gov (United States)

    Zhou, Chengshang

    Metal hydrides are a group of important materials known as energy carriers for renewable energy and thermal energy storage. A concept of thermal battery based on advanced metal hydrides is studied for heating and cooling of cabins in electric vehicles. The system utilizes a pair of thermodynamically matched metal hydrides as energy storage media. The hot hydride that is identified and developed is catalyzed MgH2 due to its high energy density and enhanced kinetics. TiV0.62Mn1.5, TiMn2, and LaNi5 alloys are selected as the matching cold hydride. A systematic experimental survey is carried out in this study to compare a wide range of additives including transitions metals, transition metal oxides, hydrides, intermetallic compounds, and carbon materials, with respect to their effects on dehydrogenation properties of MgH2. The results show that additives such as Ti and V-based metals, hydride, and certain intermetallic compounds have strong catalytic effects. Solid solution alloys of magnesium are exploited as a way to destabilize magnesium hydride thermodynamically. Various elements are alloyed with magnesium to form solid solutions, including indium and aluminum. Thermodynamic properties of the reactions between the magnesium solid solution alloys and hydrogen are investigated, showing that all the solid solution alloys that are investigated in this work have higher equilibrium hydrogen pressures than that of pure magnesium. Cyclic stability of catalyzed MgH2 is characterized and analyzed using a PCT Sievert-type apparatus. Three systems, including MgH2-TiH 2, MgH2-TiMn2, and MgH2-VTiCr, are examined. The hydrogenating and dehydrogenating kinetics at 300°C are stable after 100 cycles. However, the low temperature (25°C to 150°C) hydrogenation kinetics suffer a severe degradation during hydrogen cycling. Further experiments confirm that the low temperature kinetic degradation can be mainly related the extended hydrogenation-dehydrogenation reactions. Proof

  10. A metal hydride-polymer composite for hydrogen storage applications

    International Nuclear Information System (INIS)

    To address the issue of the breakdown into fine powders that occurs in the practical use of metal hydrides, the possibility of using a polymeric material as a matrix that contains the active metal particles was experimentally assessed. A ball milling approach in the tumbling mode was used to develop a metal hydride-polymer composite with a high metal to polymer weight ratio. The alloy powder was blended with the polymer and a coating of the metal particles was obtained. The composite was consolidated by hot pressing and the pellets were characterized in terms of their hydriding-dehydriding properties. The materials did not show significant losses in either loading capacity or kinetic properties. The polymeric matrix resulted as being stable under hydrogen cycling. Further, from SEM observation it was confirmed that the metal powders remained embedded in the polymeric matrix even after a number of cycles and that the overall dimensional integrity was retained.

  11. Theoretical Estimate of Hydride Affinities of Aromatic Carbonyl Compounds

    Institute of Scientific and Technical Information of China (English)

    AI Teng; ZHU Xiao-Qing; CHENG Jin-Pei

    2003-01-01

    @@ Aromatic carbonyl compounds are one type of the most important organic compounds, and the reductions ofthem by hydride agents such as LiAlH4 or NaBH4 are widely used in organic synthesis. The reactivity of carbonyl compounds generally increases in the following order: ketone < aldehyde, and amide < acid < ester < acid halide, which could be related to their hydride affinities (HA). In the previous paper, Robert[1] calculated the absolute HAof a series of small non-aromatic carbonyl compounds. In this paper, we use DFT method at B3LYP/6-311 + + G (2d, 2p)∥B3LYP/6-31 + G* level to estimate hydride affinities of five groups of aromatic carbonyl compounds. The detailed results are listed in Table 1.

  12. Infrared diode laser spectroscopy of lithium hydride

    International Nuclear Information System (INIS)

    The fundamental and hot bands of the vibration--rotation transitions of 6 LiH, 7 LiH, 6 LiD, and 7 LiD were observed by infrared diode laser spectroscopy at Doppler-limited resolution. Lithium hydride molecules were produced by the reaction of the Li vapor with hydrogen at elevated temperatures. Some 40 transitions were observed and, after combined with submillimeter-wave spectra reported by G. M. Plummer et al. [J. Chem. Phys. 81, 4893 (1984)], were analyzed to yield Dunham-type constants with accuracies more than an order of magnitude higher than those published in the literature. It was clearly demonstrated that the Born--Oppenheimer approximation did not hold, and some parameters representing the breakdown were evaluated. The Born--Oppenheimer internuclear distance r/sup BO//sub e/ was derived to be 1.594 914 26 (59) A, where a new value of Planck's constant recommended by CODATA was employed. The relative intensity of absorption lines was measured to determine the ratio of the permanent dipole moment to its first derivative with respect to the internuclear distance: μ/sub e/ [(partialμpartialr)/sub e/ r/sub e/ ] = 1.743(86). The pressure broadening parameter Δν/sub p/ P was determined to be 6.40 (22) MHzTorr by measuring the linewidth dependence on the pressure of hydrogen, which was about four times larger than the value for the dipole--quadrupole interaction estimated by Kiefer and Bushkovitch's theory

  13. High-Spin Cobalt Hydrides for Catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Holland, Patrick L. [Yale University

    2013-08-29

    Organometallic chemists have traditionally used catalysts with strong-field ligands that give low-spin complexes. However, complexes with a weak ligand field have weaker bonds and lower barriers to geometric changes, suggesting that they may lead to more rapid catalytic reactions. Developing our understanding of high-spin complexes requires the use of a broader range of spectroscopic techniques, but has the promise of changing the mechanism and/or selectivity of known catalytic reactions. These changes may enable the more efficient utilization of chemical resources. A special advantage of cobalt and iron catalysts is that the metals are more abundant and cheaper than those currently used for major industrial processes that convert unsaturated organic molecules and biofeedstocks into useful chemicals. This project specifically evaluated the potential of high-spin cobalt complexes for small-molecule reactions for bond rearrangement and cleavage reactions relevant to hydrocarbon transformations. We have learned that many of these reactions proceed through crossing to different spin states: for example, high-spin complexes can flip one electron spin to access a lower-energy reaction pathway for beta-hydride elimination. This reaction enables new, selective olefin isomerization catalysis. The high-spin cobalt complexes also cleave the C-O bond of CO2 and the C-F bonds of fluoroarenes. In each case, the detailed mechanism of the reaction has been determined. Importantly, we have discovered that the cobalt catalysts described here give distinctive selectivities that are better than known catalysts. These selectivities come from a synergy between supporting ligand design and electronic control of the spin-state crossing in the reactions.

  14. Thallous and cesium halide materials for use in cryogenic applications

    International Nuclear Information System (INIS)

    Certain thallous and cesium halides, either used alone or in combination with other ceramic materials, are provided in cryogenic applications such as heat exchange material for the regenerator section of a closed-cycle cryogenic refrigeration section, as stabilizing coatings for superconducting wires, and as dielectric insulating materials. The thallous and cesium halides possess unusually large specific heats at low temperatures, have large thermal conductivities, are nonmagnetic, and are nonconductors of electricity. They can be formed into a variety of shapes such as spheres, bars, rods, or the like and can be coated or extruded onto substrates or wires. (author)

  15. Dissolution and Precipitation Temperatures of δ Hydrides in Zirconium

    International Nuclear Information System (INIS)

    Anelastic effects due to the formation and dissolution of hydrides on crystal bar Zirconium (O-6 and 2x10-5 , in a gaseous atmosphere (He) to allow a better thermal conductivity inside the pendulum.Hydriding was achieved inside the pendulum by the inlet of hydrogen gas.The final hydrogen contents was determined by fusion analysis and resulted in 36 ppm.The first ''in situ'' hydriding is obtained by introducing an hydrogen pressure of 60kPa in the pendulum during 1h at 295K. Then, the hydrogen atmosphere is extracted by mechanical vacuum and an helium atmosphere is reinserted.The IF and G measurements are made in this condition. During the first heating an anomaly at 430K and a little step in the modulus G are obtained, indicating a d dissolution temperature TSSD of 430K for 8.6 wt ppm of H.After a solubilization of 10min at 495K, there are simultaneous effects: a step in G and an IF peak which is not enough developed on its right side.They presume a d precipitation temperature TSSP of 485K for 20 wt ppm of H. After a 1h at 490K, the peaks are again obtained with slight changes.The second ''in situ'' hydration during 8h at 173K, give rise to several peaks and modulus variations in the temperature range (300-400)K which are assessed to be due to transitions occurring to metastable γ and ε hydrides formed upon hydriding at low temperature, and to the δ hydride

  16. Selective chemical binding enhances cesium tolerance in plants through inhibition of cesium uptake

    Science.gov (United States)

    Adams, Eri; Chaban, Vitaly; Khandelia, Himanshu; Shin, Ryoung

    2015-03-01

    High concentrations of cesium (Cs+) inhibit plant growth but the detailed mechanisms of Cs+ uptake, transport and response in plants are not well known. In order to identify small molecules with a capacity to enhance plant tolerance to Cs+, chemical library screening was performed using Arabidopsis. Of 10,000 chemicals tested, five compounds were confirmed as Cs+ tolerance enhancers. Further investigation and quantum mechanical modelling revealed that one of these compounds reduced Cs+ concentrations in plants and that the imidazole moiety of this compound bound specifically to Cs+. Analysis of the analogous compounds indicated that the structure of the identified compound is important for the effect to be conferred. Taken together, Cs+ tolerance enhancer isolated here renders plants tolerant to Cs+ by inhibiting Cs+ entry into roots via specific binding to the ion thus, for instance, providing a basis for phytostabilisation of radiocesium-contaminated farmland.

  17. Selective chemical binding enhances cesium tolerance in plants through inhibition of cesium uptake

    DEFF Research Database (Denmark)

    Adams, Eri; Chaban, Vitaly; Khandelia, Himanshu; Shin, Ryoung

    2015-01-01

    High concentrations of cesium (Cs(+)) inhibit plant growth but the detailed mechanisms of Cs(+) uptake, transport and response in plants are not well known. In order to identify small molecules with a capacity to enhance plant tolerance to Cs(+), chemical library screening was performed using...... Arabidopsis. Of 10,000 chemicals tested, five compounds were confirmed as Cs(+) tolerance enhancers. Further investigation and quantum mechanical modelling revealed that one of these compounds reduced Cs(+) concentrations in plants and that the imidazole moiety of this compound bound specifically to Cs......(+). Analysis of the analogous compounds indicated that the structure of the identified compound is important for the effect to be conferred. Taken together, Cs(+) tolerance enhancer isolated here renders plants tolerant to Cs(+) by inhibiting Cs(+) entry into roots via specific binding to the ion thus, for...

  18. Photoelectron spectroscopy of boron aluminum hydride cluster anions

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Haopeng; Zhang, Xinxing; Ko, Yeon Jae; Gantefoer, Gerd; Bowen, Kit H., E-mail: kbowen@jhu.edu, E-mail: kiran@mcneese.edu [Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Li, Xiang [Center for Space Science and Technology, University of Maryland–Baltimore County, Baltimore, Maryland 21250 (United States); Kiran, Boggavarapu, E-mail: kbowen@jhu.edu, E-mail: kiran@mcneese.edu [Department of Chemistry and Physics, McNeese State University, Lake Charles, Louisiana 70609 (United States); Kandalam, Anil K. [Department of Physics, West Chester University, West Chester, Pennsylvania 19383 (United States)

    2014-04-28

    Boron aluminum hydride clusters are studied through a synergetic combination of anion photoelectron spectroscopy and density functional theory based calculations. Boron aluminum hydride cluster anions, B{sub x}Al{sub y}H{sub z}{sup −}, were generated in a pulsed arc cluster ionization source and identified by time-of-flight mass spectrometry. After mass selection, their photoelectron spectra were measured by a magnetic bottle-type electron energy analyzer. The resultant photoelectron spectra as well as calculations on a selected series of stoichiometries reveal significant geometrical changes upon substitution of aluminum atoms by boron atoms.

  19. Energy management of fuel cell electric vehicle with hydrid tanks

    OpenAIRE

    Ravey, Alexandre; FAIVRE, Sébastien; HIGEL, Charles; HAREL, Fabien; Djerdir, Abdesslem

    2014-01-01

    This paper proposes a novel control strategy for fuel cell electric vehicle including hydrid tanks using fuzzy logic controller. The aim of the study is to manage both thermal and electric energy with the same controller in order to use the fuel cell system as a range extender by preventing the batteries state of charge to drop too quickly. The presented controller use both batteries state of charge and thermal status of hydrid tank to control the fuel cell power. This work is a part of the M...

  20. Hydriding and dehydriding properties of CaSi

    International Nuclear Information System (INIS)

    The hydriding and dehydriding properties of CaSi were investigated both theoretically and experimentally. First-principles calculations suggested that CaSiH n is thermodynamically stable. Experimentally, the p -c isotherms clearly demonstrated plateau pressures in a temperature range of 473-573 K and the maximum hydrogen content was 1.9 weight % (wt.%) under a hydrogen pressure of 9 MPa at 473 K. The structure of CaSiH n is different from those of ZrNi hydrides, although CaSi has the CrB-type structure as well as ZrNi

  1. Exploring "aerogen-hydride" interactions between ZOF2 (Z = Kr, Xe) and metal hydrides: An ab initio study

    Science.gov (United States)

    Esrafili, Mehdi D.; Mohammadian-Sabet, Fariba

    2016-06-01

    In this work, a new σ-hole interaction formed between ZOF2 (Z = Kr and Xe) as the Lewis acid and a series of metal-hydrides HMX (M = Be, Mg, Zn and X = H, F, CN, CH3) is reported. The nature of this interaction, called "aerogen-hydride" interaction, is unveiled by molecular electrostatic potential, non-covalent interaction, quantum theory of atoms in molecules and natural bond orbital analyses. Our results indicate that the aerogen-hydride interactions are quite strong and can be comparable in strength to other σ-hole bonds. An important charge-transfer interaction is also associated with the formation of OF2Z⋯HMX complexes.

  2. Observations on Hydride Structures at the Tip of Arrested Cracks Grown under Conditions of Delayed Hydride Cracking

    International Nuclear Information System (INIS)

    One sample of Zr2.5%Nb and one sample of cold worked and stress relieved Zircaloy-4 which have been tested for hydrogen induced crack growth have been examined in the crack tip region with the aim of determining the mechanism behind the growth of cracks. The proposed mechanisms are brittle failure of a crack tip hydride and hydrogen enhanced localized shear. The examinations were done by TEM and SEM. However attempts to produce a TEM specimen with a thinned region at the tip of the crack were unsuccessful in both samples. One feature observed in the Zr2.5%Nb material may however be an indication of intense shear deformation at the tip of the crack. On the other hand all observations on the Zircaloy-4 sample indicate precipitation of hydrides ahead of the crack tip and the presence of hydrides on the crack flanks

  3. Chemical Hydride Slurry for Hydrogen Production and Storage

    Energy Technology Data Exchange (ETDEWEB)

    McClaine, Andrew W

    2008-09-30

    The purpose of this project was to investigate and evaluate the attractiveness of using a magnesium chemical hydride slurry as a hydrogen storage, delivery, and production medium for automobiles. To fully evaluate the potential for magnesium hydride slurry to act as a carrier of hydrogen, potential slurry compositions, potential hydrogen release techniques, and the processes (and their costs) that will be used to recycle the byproducts back to a high hydrogen content slurry were evaluated. A 75% MgH2 slurry was demonstrated, which was just short of the 76% goal. This slurry is pumpable and storable for months at a time at room temperature and pressure conditions and it has the consistency of paint. Two techniques were demonstrated for reacting the slurry with water to release hydrogen. The first technique was a continuous mixing process that was tested for several hours at a time and demonstrated operation without external heat addition. Further work will be required to reduce this design to a reliable, robust system. The second technique was a semi-continuous process. It was demonstrated on a 2 kWh scale. This system operated continuously and reliably for hours at a time, including starts and stops. This process could be readily reduced to practice for commercial applications. The processes and costs associated with recycling the byproducts of the water/slurry reaction were also evaluated. This included recovering and recycling the oils of the slurry, reforming the magnesium hydroxide and magnesium oxide byproduct to magnesium metal, hydriding the magnesium metal with hydrogen to form magnesium hydride, and preparing the slurry. We found that the SOM process, under development by Boston University, offers the lowest cost alternative for producing and recycling the slurry. Using the H2A framework, a total cost of production, delivery, and distribution of $4.50/kg of hydrogen delivered or $4.50/gge was determined. Experiments performed at Boston

  4. Cesium Ion Exchange Using Tank 241-AN-104 Supernate

    International Nuclear Information System (INIS)

    The River Protection Project is to design and build a high level nuclear waste treatment facility. The waste treatment plant is to process millions of gallons of radioactive waste stored in tanks at the Hanford Site. The high level nuclear waste treatment process includes various unit operations, such as ultrafiltration, precipitation, evaporation, ion exchange, and vitrification. Ion exchange is identified as the optimal treatment method for removal of cesium-137 and Tc-99 from the waste. Extensive ion exchange testing was performed using small-scale columns with actual waste samples. The objectives of this study were to: demonstrate SuperLig 644 ion exchange performance and process steps for the removal of cesium from actual AN-104 tank waste; pretreat actual AN-104 tank waste to reduce the concentration of cesium-137 in the waste below LAW vitrification limit; produce and characterize cesium eluate solutions for use in eluate evaporation tests. The experiments consisted of batch contact and small-scale column tests. The batch contact tests measured sorption partition coefficients Kds. The Kds were used to predict the effective resin capacity. The small-scale column tests, which closely mimic plant conditions, generated loading and elution profile data used to determine whether removal targets and design requirements were met

  5. A method for reducing the cesium-137 content in meat

    International Nuclear Information System (INIS)

    Reports a study of a method for reducing the amount of cesium-137 in meat from wild animals. The method is intended for use in the kitchen and is based on a combined leaching and mechanical process. (K.A.E.)

  6. Cesium-137 Levels Detected in Otters from Austria

    Directory of Open Access Journals (Sweden)

    Gutleb A.C.

    1991-02-01

    Full Text Available Pollution seems to be one of the most important causes for the decline of the European otter (Lutra lutra. The accident in the Chernobyl nuclear power plant added another aspect to environmental pollution. Few data on cesium-137 contents in otters are available, so levels were measured in 3 otters from Austria. All levels found were very low.

  7. Fission-product tellurium and cesium telluride chemistry revisited

    International Nuclear Information System (INIS)

    The chemistry of fission-product tellurium is discussed with a focus on conditions in an operating CANDU reactor and in an accident scenario, i.e., a loss of coolant accident (LOCA). Cesium telluride, Cs2Te, is likely to be one of the most abundant tellurium species released to containment. Available thermodynamic data on gas phase Cs2Te is not complete; hence the volatility of cesium telluride was studied by Knudsen-cell mass spectrometry. Cesium telluride was found to vapourize incongruently, becoming more tellurium-rich in the condensed phase as vapourization progressed. Vapour-phase species that were observed were elemental cesium and tellurium, CsTe, Cs2Te, Cs2Te2 and Cs2Te3. Second-law enthalpies and entropies were obtained for many of these species, and a third-law value, ΔH298o, of 186 ± 2 kJ·mol-1 was obtained for Cs2Te. (author)

  8. Discovery of Cesium, Lanthanum, Praseodymium and Promethium Isotopes

    OpenAIRE

    May, E.; Thoennessen, M

    2011-01-01

    Currently, forty-one cesium, thirty-five lanthanum, thirty-two praseodymium, and thirty-one promethium, isotopes have been observed and the discovery of these isotopes is discussed here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.

  9. Strontium-90 and cesium-137 in fresh water

    International Nuclear Information System (INIS)

    Japan Chemical Analysis Center has analysed the strontium-90 and Cesium-137 contents in fresh water from 7 prefectures in Japan by the commission of Science and Technology Agency of Japanese Government. The method described in ''Radioactivity Survey Data in Japan No. 43 (NIRS-RSD-43, 1977) was applied to the analysis of these two radionuclides in samples. (author)

  10. Cesium ion desorption ionization with Fourier transform mass spectrometry

    International Nuclear Information System (INIS)

    Cesium ions (Cs+) are used for the production of the feed ions necessary to obtain Fourier transform mass spectra (FTMS). The molecule chosen for the initial study of this Cs+ desorption ionization (DI-FTMS) was vitamin B-12 because of its nonvolatile, thermally labile character. 21 references

  11. Membrane-based separation technologies for cesium, strontium, and technetium

    Energy Technology Data Exchange (ETDEWEB)

    Kafka, T.

    1996-10-01

    This work is one of two parallel projects that are part of an ESP task to develop high-capacity, selective, solid extractants for cesium, strontium, and technetium from nuclear wastes. In this subtask, Pacific Northwest National Laboratory (PNNL) is collaborating with 3M, St. Paul, Minnesota, working in cooperation with IBC Advanced Technologies, American Fork, Utah.

  12. Hot demonstration of proposed commercial cesium removal technology

    International Nuclear Information System (INIS)

    This report describes the work done in support of the development of technology for the continuous removal and concentration of radioactive cesium in supernatant from Melton Valley Storage Tanks (MVSTs) at the ORNL site. The primary objective was to test candidate absorbers and ion exchangers under continuous-flow conditions using actual supernatant from the MVSTs. An experimental system contained in a hot-cell facility was constructed to test the materials in columns or modules using the same batch of supernatant to allow comparison on an equal basis. Resorcinol/formaldehyde (RF) resin was evaluated at three flow rates with 50% breakthrough ranges of 35 to 50 column volumes (CV) and also through a series of five loading/elution/regeneration cycles. The results reported here include the cesium loading breakthrough curves, elution curves (when applicable), and operational problems and observations for each material. The comparative evaluations should provide critical data for the selection of the sorbent for the ORNL Cesium Removal Demonstration project. These results will be used to help determine the design parameters for demonstration-scale systems. Such parameters include rates of cesium removal, quantity of resin or sorbent to be used, and elution and regeneration requirements, if applicable

  13. Cesium-137 Levels Detected in Otters from Austria

    OpenAIRE

    Gutleb A.C.; Mraz, G.

    1991-01-01

    Pollution seems to be one of the most important causes for the decline of the European otter (Lutra lutra). The accident in the Chernobyl nuclear power plant added another aspect to environmental pollution. Few data on cesium-137 contents in otters are available, so levels were measured in 3 otters from Austria. All levels found were very low.

  14. Studies of boron hydrides: new heteroboranes

    International Nuclear Information System (INIS)

    I. The chemistry of the bipentaborane 2,2'-(B5H8)2 is investigated to some extent. Pyrolysis of 2,2'-(B5H8)2 resulted in the formation of non-volatile solid boron hydrides and hydrogen. Treatment of 2,2'-(B5H8)2 with bromine in the presence of AlBr3 resulted in the isolation of 1,1'Br2-2,2'-(B5H7)2. Reaction of 2,2'-(B5H8)2 with deprotonating agents resulted in the formation of the corresponding anions. Reaction of 2,2'-(B5H8)2 with diborane followed by acidification afforded n-B9H15 and B10H14 in moderate yield. II. Reaction of K+B9H12S- with potassium polyselenide resulted in the isolation of stable white crystals of B9H9SSe. Treatment of B9H9SSe with one equivalent of base in methanol gave the unstable heteroborane B8H9(OCH3)SSE and treatment with two equivalents of base afforded yellow crystals of B7H9SSe. Reaction of K+B9H12S- with arsenic trioxide in aqueous basic solution gave the electron-rich heteroborane, B8H8As2S in moderate yield. This resulted in the isolation and identification of Et3N.BH3 and the new metalloborane B7H7As2SCo(C5H5). Treatment of B10H11Se- with As2O3 resulted in the isolation of the stable nido-heteroborane B8H8As2Se in low yield. Reaction of B7C2H13 with potassium polyselenide gave the arachno selenacarborane B7H2C11Se in low yield. The structure of the new heteroborane is proposed on the basis of 11B and 1H nmr spectra. Reaction of B7C2H13 with AsCl3 resulted in the isolation of white stable crystals of B7C2H9As2 in 40 percent yield

  15. Uranium Hydride Nucleation Kinetics: Effects of Oxide Thickness and Vacuum Outgassing

    International Nuclear Information System (INIS)

    Many factors such as impurities in the oxide and metal, microstructure, gas impurities, and oxide thickness may influence the rate and location of the nucleation of hydride on uranium. This work has concentrated on isolating one of these variables, the oxide thickness, and measuring the effect of the oxide thickness on uranium hydride nucleation. Uranium samples, all from the same lot, were prepared with different oxide thicknesses. The oxide thickness was measured using Rutherford Backscattering Spectroscopy. Oxidized uranium samples were then exposed to ultra-high purity hydrogen gas under constant volume conditions. Decreases in pressure indicated hydrogen uptake by the sample. The time for hydride nucleation--as well as the maximum hydriding rate--was then calculated from the measured decreases in pressure. The time to nucleate a hydride was found to increase whereas the maximum hydriding rate was found to decrease with increasing oxide thickness. The density of hydride pits also decreased with increasing oxide thickness. The observed results support the argument that the nucleation of hydride is controlled somewhat by diffusion of hydrogen through the oxide layer. Vacuum outgassing of samples, thereby removing the oxide impurities and keeping the oxide thickness constant, dramatically decreased the nucleation time and increased the maximum hydriding rate. Again, this is consistent with hydrogen diffusion through the oxide controlling the nucleation of hydride. Impurities in the oxide layer can decrease the diffusivity of hydrogen and therefore delay the nucleation of uranium hydride

  16. Selective extraction of cesium: from compound to process

    International Nuclear Information System (INIS)

    Under the French law of 30 December 1991 on nuclear waste management, research is conducted to recover long-lived fission products from high-level radioactive effluents generated by spent fuel reprocessing, in order to destroy them by transmutation or encapsulate them in specific matrices. Cesium extraction with mono and bis-crown calix(4)arenes (Frame 1) is a candidate for process development. These extractants remove cesium from highly acidic or basic pH media even with high salinity. A real raffinate was treated in 1994 in a hot cell to extract cesium with a calix-crown extractant. The success of this one batch experiment confirmed the feasibility of cesium decontamination from high-level liquid waste. It was then decided to develop a process flowchart to extract cesium selectively from high-level raffinate, to be included in the general scheme of long-lived radionuclide partitioning. It was accordingly decided to develop a process based on liquid-liquid extraction and hence optimize a calixarene/diluent solvent according to: - hydraulic properties: density, viscosity, interfacial tension, - chemical criteria: sufficient cesium extraction (depending on the diluent), kinetics, third phase elimination... New mono-crown-calixarenes branched with long aliphatic groups (Frame 2) were designed to be soluble in aliphatic diluents. To prevent third phase formation associated with nitric acid extraction, the addition of modifiers (alcohol, phosphate and amide) in the organic phase was tested (Frame 3). Table 1 shows examples of calixarene/diluent systems suitable for a process flowchart, and Figure 2 provides data on cesium extraction with these new systems. Alongside these improvements, a system based on a modified 1,3-di(n-octyl-oxy)2,4-calix[4]arene crown and a modified diluent was also developed, considering a mixed TPH/NPHE system as the diluent, where TPH (hydrogenated tetra propylene) is a common aliphatic industrial solvent and NPHE is nitrophenyl

  17. Internal friction study of hydrides in zirconium at low hydrogen contents

    International Nuclear Information System (INIS)

    Full text: Internal friction and shear modulus measurements were carried out on crystal bar zirconium in the as received and hydride conditions using an inverted forced pendulum. Hydriding was achieved in two ways: inside and out of the pendulum. The final hydrogen content determined by fusion analysis in the 'in situ' hydride sample was of 36 ppm. Another sample was hydride by the cathodic charge method with 25 ppm. The thermal solid solubility (TSS) phase boundary presents hysteresis between the precipitation (TSSP) and the dissolution (TSSD) temperatures for the zirconium hydrides. During the first thermal cycling the anelastic effects could be attributed to the δ, ε and metastable γ zirconium hydrides. After 'in situ' annealing at 490 K, these peaks completely disappear in the electrolytically charged sample, while in the 'in situ' hydride, the peaks remain with decreasing intensity. This effect can be understood in terms of the different surface conditions of the samples. (author)

  18. Comparison of irradiation hardening and microstructure evolution in ion-irradiated delta and epsilon hydrides

    Energy Technology Data Exchange (ETDEWEB)

    Oono, Naoko, E-mail: n-oono@eng.hokudai.ac.jp [Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); Kasada, Ryuta [Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); Higuchi, Toru; Sakamoto, Kan; Nakatsuka, Masafumi [Nippon Nuclear Fuel Development Co., Ltd., 2163 Naritacho Oarai, Higashi-Ibaraki, Ibaraki 311-1313 (Japan); Hasegawa, Akiko; Kondo, Sosuke; Iwata, Noriyuki Y.; Matsui, Hideki; Kimura, Akihiko [Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan)

    2013-11-15

    A δ-Zr-hydride was irradiated with 6.4 MeV Fe{sup 3+} ions to clarify the relationship between hardening and microstructural changes of bulk Zr-hydrides under neutron irradiation. Irradiation hardening was measured by nanoindentation tests. Transmission electron microscope cross-sectional observations showed that the deformation mechanism of the δ-Zr-hydride was both slip and twinning. Dislocation loops were observed in the irradiated hydride matrix. These irradiation-induced defects make slip deformation difficult and consequently promote the twin deformation of δ-Zr-hydride. This work is a continuation of the previous our work (J. Nucl. Mater. 419 (2011) 366–370) focused upon ε-Zr-hydride and we discuss a comparison between the two Zr-hydrides.

  19. Cooling Performance Improvement of the Heat Driven Type Metal Hydride Refrigerator-Heat Transfer Enhancement Influence of Metal Hydride Sheet Loading Into a Metal Hydride Particle Bed

    OpenAIRE

    Bae, Sangchul; Katsuta, Masafumi; Homma, Ikuto; Morita, Eiji

    2012-01-01

    In the refrigeration and air conditioning fields, the demands of energy conservation and renewable energy have been increased recently. In this study, we aim at the development of the heat driven type metal hydride (abbr., MH) that can be driven by the low temperature exhaust or solar heat under 100ᵒC. In order to use this system commercially, heat transfer enhancement of MH particle bed, activation characteric improvement and production cost reduction of MH must be achieved. In this study, w...

  20. Electrochromism of Mg-Ni hydride switchable mirrors

    Science.gov (United States)

    Isidorsson, Jan; Giebels, I. A. M. E.; Di Vece, M.; Griessen, Ronald

    2001-11-01

    Switchable mirrors have so far been made of rare-earth and rare-earth-magnesium based metal-hydrides. In this investigation we study Mg-Ni-hydrides, which have been shown by Richardson et al. to exhibit switchable properties similar to those of the rare-earth hydrides. Cyclic voltammetry on MgzNiHx samples with 0.8 less than z less than 3.7 shows that addition of one Mg atom per Mg2Ni gives the best ab/desorption kinetics for hydrogen. X- ray diffraction reveals a structural change as hydrogen is absorbed. The metal-insulator transition is confirmed with simultaneous resistivity measurements. A pressure- composition isotherm of Mg2NiHx is also determined electrochemically. Optical spectrometry during gas loading gives an optical band gap of 1.6 eV for Mg2NiH4. This gap increases with increasing Mg content in a way similar to that of the Mg-doped rare-earth hydrides.

  1. Structural deformation of metallic uranium surrounding hydride growth sites

    International Nuclear Information System (INIS)

    Highlights: • UH3 formation on uranium surfaces by a controlled uptake of hydrogen at 240 °C. • Large hydride growths (35–125 μm in diameter) form at the surface. • Confined hydride expansion during growth generates stress in the subsurface. • EBSD scans found micro-cracking and twins as forms of stress relief in the metal. - Abstract: Electron backscatter diffraction (EBSD) was utilised to probe the microstructure of uranium metal in the vicinity of surface corrosion pits, resulting from hydrogen exposure (5 × 104 Pa, at 240 °C). Microstructural analysis of the surface revealed a subtle increase of grain orientation variation for grains at the border of the hydride growths. Cross sectional analysis, at pit sites, revealed significant microstructure deformation in the form of crystal twinning and micro-cracking beneath the surface. These observations provide qualitative evidence that local stress intensities generated as a consequence of hydride growth and confinement, were sufficient to cause deformation within the parent metal

  2. Design and integration of a hydrogen storage on metallic hydrides

    International Nuclear Information System (INIS)

    This work presents a hydrogen storage system using metal hydrides for a Combined Heat and Power (CHP) system. Hydride storage technology has been chosen due to project specifications: high volumetric capacity, low pressures (≤ 3.5 bar) and low temperatures (≤ 75 C: fuel cell temperature). During absorption, heat from hydride generation is dissipated by fluid circulation. An integrated plate-fin type heat exchanger has been designed to obtain good compactness and to reach high absorption/desorption rates. At first, the storage system has been tested in accordance with project specifications (absorption 3.5 bar, desorption 1.5 bar). Then, the hydrogen charge/discharge times have been decreased to reach system limits. System design has been used to simulate thermal and mass comportment of the storage tank. The model is based on the software Fluent. We take in consideration heat and mass transfers in the porous media during absorption/desorption. The hydride thermal and mass behaviour has been integrated in the software. The heat and mass transfers experimentally obtained have been compared to results calculated by the model. The influence of experimental and numerical parameters on the model behaviour has also been explored. (author)

  3. Nanocrystalline Metal Hydrides Obtained by Severe Plastic Deformations

    Directory of Open Access Journals (Sweden)

    Jacques Huot

    2012-01-01

    Full Text Available It has recently been shown that Severe Plastic Deformation (SPD techniques could be used to obtain nanostructured metal hydrides with enhanced hydrogen sorption properties. In this paper we review the different SPD techniques used on metal hydrides and present some specific cases of the effect of cold rolling on the hydrogen storage properties and crystal structure of various types of metal hydrides such as magnesium-based alloys and body centered cubic (BCC alloys. Results show that generally cold rolling is as effective as ball milling to enhance hydrogen sorption kinetics. However, for some alloys such as TiV0.9Mn1.1 alloy ball milling and cold rolling have detrimental effect on hydrogen capacity. The exact mechanism responsible for the change in hydrogenation properties may not be the same for ball milling and cold rolling. Nevertheless, particle size reduction and texture seems to play a leading role in the hydrogen sorption enhancement of cold rolled metal hydrides.

  4. Study on the effect of hydrogen purification with metal hydride

    International Nuclear Information System (INIS)

    The effects of hydrogen purification with a AB5-type metal hydride were studied for the development of hydrogen purification system. The system set up two packed-beds, heat exchangers, data acquisition equipment and automatic control unit was used in the work and the compositions of two different gas-mixtures have CO, CH4, CO2, O2 and N2. We investigated about its tolerance against impurities, pressure-composition-isotherm and life cycle test, XRD and particle size analysis with a used metal hydride. Gas chromatograph was used for the analysis of feed and product gas. The used metal hydride is a La, Nd-rich Mm-based AB5 type which has the hydrogen storage capacity of 1.4 wt%. In life cycle test, there were no change of plateau pressure and hysteresis after 600 cycles but hydrogen storage capacity was decreased by about 6.8% and 10.7% after 220, 600 cycles, respectively. The used sample is high strong against CH4 and CO2 but very weak in CO atmosphere. The hydrogen purification performance with gas mixtures was decreased in the order of CH4 ≥ CO ≥ O2 ≥ N2 ≥ CO2. The reason CO investigated high purification effect in gas mixture is due to a strong chemisorption in metal hydride matrix that CO was not released out of the alloy. (authors)

  5. Hydrogen adsorption on palladium and palladium hydride at 1 bar

    DEFF Research Database (Denmark)

    Johansson, Martin; Skulason, Egill; Nielsen, Gunver;

    2010-01-01

    The dissociative sticking probability for H-2 on Pd films supported on sputtered Highly Ordered Pyrolytic Graphite (HOPG) has been derived from measurements of the rate of the H-D exchange reaction at 1 bar. The sticking probability for H-2, S. is higher on Pd hydride than on Pd (a factor of 1.4 ...

  6. Process of forming a sol-gel/metal hydride composite

    Science.gov (United States)

    Congdon, James W.

    2009-03-17

    An external gelation process is described which produces granules of metal hydride particles contained within a sol-gel matrix. The resulting granules are dimensionally stable and are useful for applications such as hydrogen separation and hydrogen purification. An additional coating technique for strengthening the granules is also provided.

  7. Demonstration test for decontamination technology of cesium-contaminated ash

    International Nuclear Information System (INIS)

    KEPCO Engineering and Construction Company (KEPCO E and C), architecture and engineering company of nuclear power plant, developed the 'decontamination technology of cesium-contaminated ash' in the basis of pre-owned 'decontamination technology of cesium-contaminated soil'. The new technology was demonstrated in Fukushima prefecture during 12 days from November 5, 2013, in order to verify the performance. Demonstration equipment (CEDECON-DA), with a capacity of treatment of 20 ℓ per batch, can be carried in a container in order to promote the ease of transportation and in-situ installation. Through the demonstration test it was verified the superior performance and the possibility of commercialization. This technique comprises of cesium separation and cesium coagulation processes. Briefly speaking, the principal of this process is as follows; cesium is separated from ash, detached to the coagulation and then deposited. The decontaminated ash can be disposed of into municipal landfills as conventional non-radioactive waste. The present technology is evaluated such that the disposal amount of radioactive waste will be significantly reduced. The ash with average concentration of 6,200 Bq/kg from a conventional incineration plant was used for the demonstration test. Each separate performance test has been carried out under acid, neutral and alkaline conditions, respectively. The test result for alkaline condition showed the highest decontamination ratio of 82-85% and the volume reduction ratio of 95%. Radioactive Waste Management and Nuclear Facility Decommissioning Technology Center (RANDEC) performed the radiation protection management, activity measurement and evaluation in the demonstration test results. (author)

  8. Some aspects of cesium deposition in Transilvania (Romania)

    International Nuclear Information System (INIS)

    Following the accident of the Chernobyl atomic electric power station, a great quantity of radionuclides (∼100MCi) escaped from the reactor. It was estimated that 13% of the inventory activity of cesium representing 1.5-2 MCi left the reactor. The radioactive deposits were very nonuniform for the same distance and in the same direction from Chernobyl nuclear center having a close dependence upon direction and speed of wind and pluviometric conditions. The rains, especially the storms, spectacularly increased the radioactive fallout. Although, for the first two-three days, subsequent to accident, the meteorological conditions were favorable for Romania, after April 29/30, because of the changing in the wind direction on SW (initial it was N and NW) the countries were on this direction - Romania, Bulgaria, Greece, former Yugoslavia - began to be intensely contaminated with radioactive fallout. In Romania, the radioactive cloud passing coincided with abundant rains, especially on the direction mentioned above. On this direction, the cesium deposits are of 8-2 times larger than other Romanian regions. The torrential rain which fell on May 1st 1986, in the western side of Cluj Napoca town caused an intense contamination especially with short-life isotopes as Te, I, Ba, La, Mo. Medium and long-life isotopes as Ru, Zr, Cs, Sr were present in large quantities in this area.too. For the total contribution the value obtained was 1130 kBq/m2, much larger than the average in Romania. This work presents data about cesium content of pollen samples gathered daily between 1-30 May 1986; cesium deposits in five areas and some measurements in connection with cesium mitigation in soils

  9. Thin-film metal hydrides for solar energy applications

    Energy Technology Data Exchange (ETDEWEB)

    Mongstad, Trygve Tveiteraas

    2012-11-01

    Thin-film metal hydrides may become important solar energy materials in the future. This thesis demonstrates interesting material properties of metal hydride films, relevant for applications as semiconducting materials for photovoltaic (PV) solar cells and for regulation of light using smart window technology.The work presented here has comprised an experimental study, focusing on three different materials: Magnesium hydride (MgH2), magnesium nickel hydride (Mg2NiH4) and yttrium hydride (YHx). Reactive sputter deposition was used to prepare the metal hydride film samples.This synthesis method is relatively uncommon for metal hydrides. Here,the first demonstration of reactive sputtering synthesis for YHx and Mg2NiH4 is given. Different challenges in forming singlephase, pure metal hydrides were identified: MgH2 could not be deposited without 3-16% metallic Mg present in the films, and YHx was found to react strong-ly to oxygen (O) during the deposition process. On the other hand, Mg2NiH4 films formed easily and apparently without major metallic clusters and with low O content.Mg2NiH4 is a semiconductor with an optical band gap that is suitable for PV solar cells. This study has showed that films with promising electrical and optical properties can be synthesized using reactive cosputtering of Mg and Ni. Using optical methods, the band gap for the as deposited samples was estimated to 1.54-1.76 eV, depending on the Mg-Ni composition. The asdeposited films were amorphous or nano-crystalline, but could be crystallized into the high-temperature fcc structure of Mg2NiH4 using heat treatment at 523 K. The band gap of the crystalline films was 2.1-2.2 eV, depending on the composition.A pronounced photochromic reaction to visible and UV light was observed for transparent yttrium hydride (T-YHx) samples. The optical transmission was reduced when the samples were illuminated, and the original optical transmission was restored when the samples were kept under dark conditions

  10. Synthesis of hydrides by interaction of intermetallic compounds with ammonia

    Energy Technology Data Exchange (ETDEWEB)

    Tarasov, Boris P., E-mail: tarasov@icp.ac.ru [Institute of Problems of Chemical Physics of the Russian Academy of Sciences, Chernogolovka 142432 (Russian Federation); Fokin, Valentin N.; Fokina, Evelina E. [Institute of Problems of Chemical Physics of the Russian Academy of Sciences, Chernogolovka 142432 (Russian Federation); Yartys, Volodymyr A., E-mail: volodymyr.yartys@ife.no [Institute for Energy Technology, Kjeller NO 2027 (Norway); Department of Materials Science and Engineering, Norwegian University of Science and Technology, Trondheim NO 7491 (Norway)

    2015-10-05

    Highlights: • Interaction of the intermetallics A{sub 2}B, AB, AB{sub 2}, AB{sub 5} and A{sub 2}B{sub 17} with NH{sub 3} was studied. • The mechanism of interaction of the alloys with ammonia is temperature-dependent. • Hydrides, hydridonitrides, disproportionation products or metal–N–H compounds are formed. • NH{sub 4}Cl was used as an activator of the reaction between ammonia and intermetallics. • Interaction with ammonia results in the synthesis of the nanopowders. - Abstract: Interaction of intermetallic compounds with ammonia was studied as a processing route to synthesize hydrides and hydridonitrides of intermetallic compounds having various stoichiometries and types of crystal structures, including A{sub 2}B, AB, AB{sub 2}, AB{sub 5} and A{sub 2}B{sub 17} (A = Mg, Ti, Zr, Sc, Nd, Sm; B = transition metals, including Fe, Co, Ni, Ti and nontransition elements, Al and B). In presence of NH{sub 4}Cl used as an activator of the reaction between ammonia and intermetallic alloys, their interaction proceeds at rather mild P–T conditions, at temperatures 100–200 °C and at pressures of 0.6–0.8 MPa. The mechanism of interaction of the alloys with ammonia appears to be temperature-dependent and, following a rise of the interaction temperature, it leads to the formation of interstitial hydrides; interstitial hydridonitrides; disproportionation products (binary hydride; new intermetallic hydrides and binary nitrides) or new metal–nitrogen–hydrogen compounds like magnesium amide Mg(NH{sub 2}){sub 2}. The interaction results in the synthesis of the nanopowders where hydrogen and nitrogen atoms become incorporated into the crystal lattices of the intermetallic alloys. The nitrogenated materials have the smallest particle size, down to 40 nm, and a specific surface area close to 20 m{sup 2}/g.

  11. Synthesis and enhanced hydrogen desorption kinetics of magnesium hydride using hydriding chemical vapor synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jin-Ho [Icheon Branch, Korea Institute of Ceramic Engineering and Technology (KICET), Icheon-si, Gyeonggi-do (Korea, Republic of); Kim, Byung-Goan [Korea Energy Materials Co.Ltd., 409, Daegu Technopark, 1-11, Hosan-Dong, Dalse-Gu 704-230 (Korea, Republic of); Kang, Yong-Mook, E-mail: dake@kaist.ac.kr [Department of Chemistry, Dongguk University-Seoul, 100715 Seoul (Korea, Republic of)

    2012-07-15

    Highlights: Black-Right-Pointing-Pointer We synthesized pure MgH{sub 2} by a hydriding chemical vapor synthesis process in a hydrogen atmosphere. Black-Right-Pointing-Pointer The particle size HCVS-MgH{sub 2} was drastically reduced to the sub-micron or micrometer-scale. Black-Right-Pointing-Pointer HCVS-MgH{sub 2} showed different shapes (needle-like nanofibers and angulated plate) depending on the deposited position. Black-Right-Pointing-Pointer HCVS-MgH{sub 2} desorbed hydrogen up to about 7.2 wt% and 7.1 wt%. - Abstract: This paper describes the hydriding chemical vapor synthesis (HCVS) of the hydrogen storage alloy MgH{sub 2} in a hydrogen atmosphere and the product's hydrogenation properties. Mg powder was used as a starting material to produce submicron MgH{sub 2} and uniformly heated to a temperature of 600 Degree-Sign C for Mg vaporization. The effects of deposited positions in HCVS reactor on the morphology and the composition of the obtained products were examined by using X-ray diffraction (XRD), scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) analyses. It is clearly seen that after the HCVS process, the particle size of synthesized MgH{sub 2} was drastically reduced to the sub-micron or micrometer-scale and these showed different shapes (needle-like nanofibers and angulated plate) depending on the deposited position. The hydrogen desorption temperatures of HCVS-MgH{sub 2} were measured using a differential scanning calorimeter (DSC). It was found that after the HCVS process, the desorption temperature of HCVS-MgH{sub 2} decreased from 430 to 385 Degree-Sign C and, simultaneously, the smallest particle size and the highest specific surface area were obtained. These observations indicate that the minimum hydrogen desorption temperature of HCVS-MgH{sub 2} powder with needle-like form can be obtained, and that this temperature is dependent on the particle size and the specific surface area of the products. The thermogravimetric

  12. Distribution and retention of cesium and strontium in Swedish boreal forest ecosystems

    International Nuclear Information System (INIS)

    The retention and distribution of cesium, and to some extent strontium, in forest environments are being studied at three sites in Sweden. The main part of the cesium found in the soil was recovered in horizons rich in organic matter. The cesium was retained in the soil organic matter in a more or less extractable form. As different soil types have a different distribution pattern of organic matter, the distribution of cesium will depend on the forest soil type. The clay content in Swedish forest soils is, in general, low which will mitigate the retention of cesium in the soil mineral horizons. The cesium and strontium present in the trees was considered to be an effect of assimilation by the tissues in the canopy as well as by the roots. The redistribution of cesium within the trees was extensive which was considered to be the effect of a high mobility of cesium in the trees. The recovery of strontium-90 in pines, in relation to the deposition rate was higher compared to the relative recovery of cesium-137, 30 years after deposition. The cesium and strontium will remain in the forest environment for a considerable time but can be reduced by forest practice, by leaching out of the soil profile or by radioactive decay

  13. Exploring metal hydrides using autoclave and multi-anvil hydrogenations

    Science.gov (United States)

    Puhakainen, Kati

    Metal hydride materials have been intensively studied for hydrogen storage applications. In addition to potential hydrogen economy applications, metal hydrides offer a wide variety of other interesting properties. For example, hydrogen-dominant materials, which are hydrides with the highest hydrogen content for a particular metal/semimetal composition, are predicted to display high-temperature superconductivity. On the other side of the spectrum are hydrides with small amounts of hydrogen (0.1 - 1 at.%) that are investigated as viable magnetic, thermoelectric or semiconducting materials. Research of metal hydride materials is generally important to gain fundamental understanding of metal-hydrogen interactions in materials. Hydrogenation of Zintl phases, which are defined as compounds between an active metal (alkali, alkaline earth, rare earth) and a p-block metal/semimetal, were attempted by a hot sintering method utilizing an autoclave loaded with gaseous hydrogen (Hydride formation competes with oxidative decomposition of a Zintl phase. The oxidative decomposition, which leads to a mixture of binary active metal hydride and p-block element, was observed for investigated aluminum (Al) and gallium (Ga) containing Zintl phases. However, a new phase Li2Al was discovered when Zintl phase precursors were synthesized. Using the single crystal x-ray diffraction (SCXRD), the Li2Al was found to crystallize in an orthorhombic unit cell (Cmcm) with the lattice parameters a = 4.6404(8) Å, b = 9.719(2) Å, and c = 4.4764(8) Å. Increased demand for materials with improved properties necessitates the exploration of alternative synthesis methods. Conventional metal hydride synthesis methods, like ball-milling and autoclave technique, are not responding to the demands of finding new materials. A viable alternative synthesis method is the application of high pressure for the preparation of hydrogen-dominant materials. Extreme pressures in the gigapascal ranges can open access to

  14. Hydride redistribution and crack growth in Zr-2.5 wt.% Nb stressed in torsion

    International Nuclear Information System (INIS)

    The effect of applied shear stresses on zirconium hydride solubility in a zirconium alloy was investigated. Recent studies have shown that zirconium hydride precipiates probably nucleate and grow by means of a shear transformation mechanism. It is postulated that these transformation shear strains can interact with applied shear stress gradients in the same way that the dilatational strains can interact with a dilatational stress gradient, providing a driving force for hydride accumulation, hydride embrittlement and crack propagation. To test this proposition, crack growth experiments were carried out under torsional loading conditions on hydrided, round notched bar specimens of cold-worked Zr-2.5 wt.% Nb cut from Pickering-type pressure tube material. Postmortem metallographic examination of the hydride distribution in these samples showed that, in many cases, the hydrides appeared to have reoriented in response to the applied shear stress and that hydride accumulation at the notch tip had occurred. However, except in a few cases, the rate of accumulation of reoriented hydrides at the notch tip due to applied shear stresses was much less than the rate due to corresponding applied uniaxial stresss. Moreover, the process in shear appears to be more sensitive to the inital hydride size. Attempts to elucidate the fracture mechanism by fractographic examination using scanning and replica transmission electron microscopy proved to be inconclusive because of smearing of the fracture face. (auth)

  15. Metal Hydride Wall Stress Measurements on a Four-Inch Short (FISH) Bed

    International Nuclear Information System (INIS)

    A 38 cm (15 inch) long metal hydride bed fabricated using 11.4 cm (4.5 inch) O.D., standard schedule 316/316L stainless steel pipe was fitted with 22 strain gauges to measure tangential and longitudinal stress resulting from hydride absorption and desorption cycling. Tests were conducted using two different LaNi4.25Al0.75 metal hydride fill-levels in the bed.Tests conducted with hydride filled to two-thirds (1.75L) of the 2.63L total bed volume resulted in a maximum stress less than one-third of the pipe's ASME Code allowable, for hydride absorption up to a hydrogen-to-metal ratio (H/M) of 0.86. After 15 absorption/desorption tests and hydride passivation, examination of the bed interior revealed a significant decrease in particle size and increase in hydride height. The second fill level had 0.4L of fresh hydride added to the bed's cycled hydride material, and 56 absorption/desorption tests, up to a gas loading of 0.83 H/M performed. Second fill tests resulted in maximum stresses less than 40% of the ASME Code allowable. Post-test bed radiographs showed a further increase in the apparent hydride fill height, and internal component deformation

  16. In situ study of hydride precipitation kinetics and re-orientation in Zircaloy using synchrotron radiation

    International Nuclear Information System (INIS)

    The orientation and distribution of hydrides formed in zirconium alloy nuclear fuel cladding can strongly influence material behavior and in particular resistance to crack growth. The hydride microstructure and hydride platelet orientation (whether in-plane or radial relative to the cladding tubes) are crucial to determining cladding failure limits during mechanical testing. Hydride formation is normally studied by post-facto metallography, performed at room temperature and in the absence of applied stress. This study uses synchrotron radiation to observe in situ the kinetics of hydride dissolution and precipitation in previously hydrided Zircaloy samples. The experiments allow the direct observation of hydride dissolution, re-precipitation, and re-orientation, during heating and cooling under load. The solubility limits and the hydride-matrix orientation relationship determined from in situ experiments were in good agreement with previous post-facto examinations of bulk materials. The present measurements performed under stress and at temperature showed a characteristic diffraction signature of reoriented hydrides. The results suggest a threshold stress for hydride re-orientation between 75 and 80 MPa for the microstructure/texture studied. These results are discussed in light of existing knowledge.

  17. Composite Materials for Hazard Mitigation of Reactive Metal Hydrides.

    Energy Technology Data Exchange (ETDEWEB)

    Pratt, Joseph William; Cordaro, Joseph Gabriel; Sartor, George B.; Dedrick, Daniel E.; Reeder, Craig L.

    2012-02-01

    In an attempt to mitigate the hazards associated with storing large quantities of reactive metal hydrides, polymer composite materials were synthesized and tested under simulated usage and accident conditions. The composites were made by polymerizing vinyl monomers using free-radical polymerization chemistry, in the presence of the metal hydride. Composites with vinyl-containing siloxane oligomers were also polymerized with and without added styrene and divinyl benzene. Hydrogen capacity measurements revealed that addition of the polymer to the metal hydride reduced the inherent hydrogen storage capacity of the material. The composites were found to be initially effective at reducing the amount of heat released during oxidation. However, upon cycling the composites, the mitigating behavior was lost. While the polymer composites we investigated have mitigating potential and are physically robust, they undergo a chemical change upon cycling that makes them subsequently ineffective at mitigating heat release upon oxidation of the metal hydride. Acknowledgements The authors would like to thank the following people who participated in this project: Ned Stetson (U.S. Department of Energy) for sponsorship and support of the project. Ken Stewart (Sandia) for building the flow-through calorimeter and cycling test stations. Isidro Ruvalcaba, Jr. (Sandia) for qualitative experiments on the interaction of sodium alanate with water. Terry Johnson (Sandia) for sharing his expertise and knowledge of metal hydrides, and sodium alanate in particular. Marcina Moreno (Sandia) for programmatic assistance. John Khalil (United Technologies Research Corp) for insight into the hazards of reactive metal hydrides and real-world accident scenario experiments. Summary In an attempt to mitigate and/or manage hazards associated with storing bulk quantities of reactive metal hydrides, polymer composite materials (a mixture of a mitigating polymer and a metal hydride) were synthesized and tested

  18. Effect of alloy elements and hydride morphology on hydrogen embrittlement of zirconium alloy

    International Nuclear Information System (INIS)

    The effects of Nb and Sn on hydride embrittlement of Zr alloys were investigated. For this, experimental Zr alloys were prepared in a sheet shape and charged with hydrogen. The microstructure and hydride morphology were analyzed and the tensile properties were measured to understand the role of Nb and Sn on the hydride embrittlement of Zr alloy. With addition of Nb and Sn, recrystallization was retarded during the final annealing heat treatment. The retardation was mainly caused from β-Nb precipitates and Sn solute atoms, which was confirmed from texture analyses. Of the two, Sn was found to more effective in retarding recrystallization. When hydrogen was charged, hydride clusters with stacked hydride platelets were observed in unalloyed Zr. However, with addition of Nb and Sn, such hydride clusters were replaced with hydrides platelets which were more or less aligned with the rolling direction and linked up on the rolling plane, and hydride length and the spacing between hydrides were increased. This change in hydride morphology was caused by the retardation of recrystallization. Again, Sn was found to be more effective in in modifying the hydride morphology and aligning hydrides on the rolling plane. Both Nb and Sn contributed to the strengthening of Zr alloys, but Sn is more effective in strengthening than Nb. However, tensile strengths of the experimental alloys were nearly independent of the absorbed hydrogen contents. While ductility was reduced with increasing hydrogen contents, the degree of ductility loss was dependent on Nb and Sn contents which increased hydrogen solubility and retarded recrystallization. For alloys with 1%-Nb and/or 1%-Sn, increase in hydrogen solubility was the main contributor to increase in resistance to hydride embrittlement. On the other hand, for an alloy with 2%-Nb resulted in large amount of β-Nb precipitates, which in turn significantly retarded recrystallization. Therefore, the added contribution of retardation of

  19. Spectrally selective optical pumping in Doppler-broadened cesium atoms

    International Nuclear Information System (INIS)

    The D1 line spectrally selective pumping process in Doppler-broadened cesium is analyzed by solving the optical Bloch equations. The process, described by a three-level model with the Λ scheme, shows that the saturation intensity of broadened atoms is three orders of magnitude larger than that of resting atoms. The |Fg = 3> → |Fe = 4> resonance pumping can result in the ground state |Fg = 4, mF = 4> sublevel having a maximum population of 0.157 and the population difference would be about 0.01 in two adjacent magnetic sublevels of the hyperfine (HF) state Fg = 4. To enhance the anisotropy in the ground state, we suggest employing dichromatic optical HF pumping by adding a laser to excite D1 line |Fg = 4> → |Fe = 3> transition, in which the cesium magnetometer sensitivity increases by half a magnitude and is unaffected by the nonlinear Zeeman effect even in Earth's average magnetic field. (atomic and molecular physics)

  20. Electrode activation in cesium-free negative ion sources

    International Nuclear Information System (INIS)

    Features of emission electrode activation leading to enhancement of negative ion emission in cesium-free discharges are discussed. In some ion sources with cesium-free discharges, the emission of negative ions has been increased significantly by emission electrode activation using strong heating of the negative biased electrode by discharge plasma. A simple explanation of this enhancement is that it is due to an accumulation on the emission surface of the plasma electrode of impurities with low ionization potential that decreases in surface work function and increases the secondary emission of negative ions similar to ''Cesiation.'' The negative biasing of emission surface is important for accumulation and trapping the impurities on the emission surface. To effectively control the activation process it is important to directly detect the evolution of the work function and the impurity concentration during electrode activation with enhancement of negative ion emission.

  1. Trapping and cooling cesium atoms in a speckle field

    International Nuclear Information System (INIS)

    We present the results of two experiments where cold cesium atoms are trapped in a speckle field. In the first experiment, a YAG laser creates the speckle pattern and induces a far-detuned dipole potential which is a nearly-conservative potential. Localization of atoms near the intensity maxima of the speckle field is observed. In a second experiment we use two counterpropagating laser beams tuned close to a resonance line of cesium and in the lin perpendicular to lin configuration, one of them being modulated by a holographic diffuser that creates the speckle field. Three-dimensional cooling is observed. Variations of the temperature and of the spatial diffusion coefficient with the size of a speckle grain are presented. (orig.)

  2. Cesium exchange reaction on natural and modified clinoptilolite zeolites

    International Nuclear Information System (INIS)

    Cesium cation exchange reaction with K, Na, Ca and Mg ions on natural and modified clinoptilolite has been studied. Batch cation-exchange experiments were performed by placing 0.5 g of clinoptilolite into 10 ml or 20 ml of 1 x 10-3M CsCl solution for differing times. Two type deposits of clinoptilolite zeolites from, Nizny Hrabovec (NH), Slovakia and Metaxades (MX), Greece were used for ion-exchange study. The distribution coefficient (Kd) and sorption capacity (Γ) were evaluated. For the determination of K, Na, Ca and Mg isotachophoresis method, the most common cations in exchange reaction was used. Cesium sorption was studied using 137Cs tracer and measured by γ-spectrometry. (author)

  3. Kelvin Probe Studies of Cesium Telluride Photocathode for AWA Photoinjector

    CERN Document Server

    Wisniewski, Eric; Yusof, Zikri; Spentzouris, Linda; Terry, Jeff; Harkay, Katherine

    2012-01-01

    Cesium telluride is an important photocathode as an electron source for particle accelerators. It has a relatively high quantum efficiency (>1%), is sufficiently robust in a photoinjector, and has a long lifetime. This photocathode is grown in-house for a new Argonne Wakefield Accelerator (AWA) beamline to produce high charge per bunch (~50 nC) in a long bunch train. Here, we present a study of the work function of cesium telluride photocathode using the Kelvin Probe technique. The study includes an investigation of the correlation between the quantum efficiency and the work function, the effect of photocathode aging, the effect of UV exposure on the work function, and the evolution of the work function during and after photocathode rejuvenation via heating.

  4. Strontium-90 and cesium-137 in air-borne dust

    International Nuclear Information System (INIS)

    Under the commission of Science and Technology Agency, Japan Chemical Analysis Center and prefectural public health laboratories and institutes have determined the levels of strontium-90 and cesium-137 in air-borne dust samples. Dust samples were collected by the aspiration of 3000 m3 or more air at 1.0 -- 1.5 m above the ground surface in 10 prefectural public health laboratories and institutes. The samples collected during three months were combined, and were forwarded to Japan Chemical Analysis Center after carbonization. These samples were ashed in an electric muffle furnance at Japan Chemical Analysis Center. The ash to which both some carriers and hydrochloric acid were added, was destroyed under heating. The solution was dissolved into hydrochloric and filtered, after it was added with nitric acid and heated to dryness. The filtrate was radiochemically analysed for strontium-90 and cesium-137 with low background beta-ray spectrometer. (author)

  5. Cesium and lead uptake by CSH phases of hydrated cement

    International Nuclear Information System (INIS)

    As Kd from radwaste elements in concrete systems show a wide range of values, a modelling of cesium and lead immobilization in Calcium Silicate Hydrate (CSH, xCaO.SiO2.H2O, with 0.7 (aged cements)SiOH) and precipitation equilibria. Values of Kd from cesium and lead in CSH matrix can thus be calculated with Ca/Si evolution and ionic strength effect. Predictive calculations have been carried out with success with different Ca/Si ratios, ionic strengths and liquid/solid ratios, and results are well superimposed with experimental isotherm data. If the CSH really allow accounting for the radwaste behavior in hydrated cement matrices, this model can be used in safety assessment calculations, with varying pH and [Ca2+] as cement degradation state parameters. Copyright (2001) Material Research Society

  6. New thermodynamic regularity for cesium over the whole liquid range

    CERN Document Server

    Ghatee, M H

    2001-01-01

    In this paper we derive an equation of state for liquid cesium based on a suggested potential function in accord to the characteristics large attraction and soft repulsion at the asymptotes of interaction potentials. By considering the interaction of nearest adjacent atoms in dense fluid, the equation of state predicts that the isotherm is linear function of, where is the compression factor, is the molar volume, and is the molar density. The linear parameters are identified as interaction coefficients related to attraction and repulsion, and are used to evaluate the molecular parameters with interesting implications. The isotherm is intended to resolve the particular thermodynamic properties of alkali metals, which have been known for their unusual change of the nature of intermolecular force as the characteristic metal-nonmetal transition range is approached. When applied to liquid cesium, the isotherms persist linear over the whole liquid range including the metal non-metals transition range and at the crit...

  7. Strontium-90 and cesium-137 in air-borne dust

    International Nuclear Information System (INIS)

    The levels of strontium-90 and cesium-137 in airborne dust have been determined by Japan Chemical Analysis Center under the contact with Science and Technology Agency. Dust samples were collected at 1.0 -- 1.5m above the ground surface with electrostatic precipitators or on filter papers by each prefectural public health laboratories and institutes in 9 prefectures, and these samples were forwarded to Japan Chemical Analysis Center after the carbonization. These samples were asked in an electric muffle furnance at Japan Chemical Analysis Center. The ask to which both some carriers and hydrochloric acid were added, was destroyed under heating. The solution was dissolved into hydrochloric acid and filtered, after it was added with nitric acid and heated to dryness. The filtrate was analysed for strontium-90 and cesium-137 using the method recommended by science and Technology Agency. (author)

  8. Cesium-137, a drama recounted; Cesio-137, um drama recontado

    Energy Technology Data Exchange (ETDEWEB)

    Vieira, Suzane de Alencar

    2013-01-15

    The radiological accident with Cesium-137, which started on Goiania in 1987, did not stop with the end of radiological contamination and continues in a judicial, scientific and narrative process of identification and recognition of new victims. The drama occupies a central place on the dynamics of radiological event, as it extends its limits, inflects its intensity and updates the event. As a narrative of the event, the ethnography incorporates and brings up to date the drama as an analysis landmark and the description of the theme as it is absorbed by a dramatic process. Cesium-137, a drama recounted is a textual experimentation based on real events and characters picked out from statements reported in various narratives about the radiological accident. (author)

  9. Migration behavior of cesium in compacted sodium montmorillonite

    International Nuclear Information System (INIS)

    For safety assessments of geological disposal of high-level radioactive wastes, it is important to study the migration behavior of radioactive nuclides in compacted bentonite. In the present study, the apparent diffusion coefficients and activation energies of the diffusion were determined for cesium ions in compacted montmorillonite, a major clay mineral in bentonite. The activation energies obtained in the present study were 32.9 to 52.9 kJ mol-1, clearly higher than for the diffusion of cesium ions in free water, 16.2 kJ mol-1. The activation energies for Na-montmorillonite specimens with dry densities of 1.0, 1.2, and 1.4 x 103 kg m-3 were similar at approximately 34 kJ mol-1. When the dry density of the Na-montmorillonite specimens increases, the activation energy also increases, to reach 52.9 kJ mol-1 at 1.8 x 103 kg m-3. These findings suggest that the cesium in the compacted Na-montmorillonite diffuses with a different process from that in free water. Basal spacings were determined by the X-ray diffraction method for water-saturated, compacted Na-montmorillonite specimens. Three-water layer hydrate in the interlamellar space was observed for the Na-montmorillonite with dry densities of 1.0, 1.2, and 1.4 x 103 kg m-3, where the activation energies for the diffusion were nearly constant. Only the two-water layer hydrate was found in the Na-montmorillonite with dry densities of 1.6 and 1.8 x 103 kg m-3, in which the activation energy increases with the dry density. It is possible that the basal spacing could affect the migration behavior of cesium in compacted Na-montmorillonite. (author)

  10. Radioactive cesium. Dynamics and transport in forestal food-webs

    International Nuclear Information System (INIS)

    This report summarises results from a radioecological study during 1994-1995 concerning turnover, redistribution and loss of radioactive Cesium (134 and 137) in boreal forest ecosystems, as well as uptake and transfer in important food-chains over moose, vole and vegetation. The basis for this report are 9 publications published 1994-95. These reports are presented in summary form. 9 refs, 17 figs

  11. Optimized production of a cesium Bose-Einstein condensate

    OpenAIRE

    Kraemer, Tobias; Herbig, Jens; Mark, Michael; Weber, Tino; Chin, Cheng; Naegerl, Hanns-Christoph; Grimm, Rudolf

    2004-01-01

    We report on the optimized production of a Bose-Einstein condensate of cesium atoms using an optical trapping approach. Based on an improved trap loading and evaporation scheme we obtain more than $10^5$ atoms in the condensed phase. To test the tunability of the interaction in the condensate we study the expansion of the condensate as a function of scattering length. We further excite strong oscillations of the trapped condensate by rapidly varying the interaction strength.

  12. Cesium dihydrophosphate monocrystal growth and certain of their properties

    International Nuclear Information System (INIS)

    Crystals of cesium dihydrophosphate (centrisymmetrical, monoclinic, point symmetric group 2/m) are obtained by methods involving solvent evaporation and temperature reduction. At -122 deg C, a ferroelectric phase transition occurs, and at 230 and 265 deg C first-kind transitions, which are not accompanied by composition changes. CsH2PO4 solubility substantially increases with higher medium acidity, and remains approximately constant in alkali medium

  13. Behaviour of radioactive cesium in northern boreal forest ecosystems

    International Nuclear Information System (INIS)

    Full text: In 1997-2001 a large number of environmental samples have been collected from the Muddusjaervi area in Finnish Lappland. These samples include soil, water, sediment, vegetation and fish samples. Radioactive contamination in this subarctic environment has mainly resulted from the nuclear weapons test fallout in the 1950s and 1960s. Chernobyl accident did not considerably increase the contamination level in this area. The Laboratory of Radiochemistry, University of Helsinki, has been studying the behaviour of fallout radionuclides in the environment and in food chains in Lappland from the beginning of the 1960s. The study area lies in the middle of northern reindeer herding area where accumulation of radioactive cesium has been observed in food chains. In this paper we report on the behaviour of radioactive cesium in soil columns. The soil in this area is typically nutrient-poor podzolic soil. Altogether thirty soil columns were collected and they were divided into horizons (litter, organic and mineral layers). The activity concentrations of the horizons were determined by gamma spectrometry. In general, cesium has been concentrated mainly in the litter and organic layers and it has not been migrated considerably to mineral layers. To study the long term behaviour of cesium in soil the activity concentrations have been compared to those found in earlier decades and to the activity concentrations earlier determined for other radionuclides, especially for Pu. A further major objective was to study runoff of radionuclides from ground to lakes and brooks and therefore many of the soil samples were collected from various distances from lakes and brooks. (author)

  14. Detection of the actinides and cesium from environmental samples

    Science.gov (United States)

    Snow, Mathew Spencer

    Detection of the actinides and cesium in the environment is important for a variety of applications ranging from environmental remediation to safeguards and nuclear forensics. The utilization of multiple different elemental concentrations and isotopic ratios together can significantly improve the ability to attribute contamination to a unique source term and/or generation process; however, the utilization of multiple elemental "signatures" together from environmental samples requires knowledge of the impact of chemical fractionation for various elements under a variety of environmental conditions (including predominantly aqueous versus arid conditions). The research reported in this dissertation focuses on three major areas: 1. Improving the understanding of actinide-mineral interactions at ultra-low concentrations. Chapter 2 reports a batch sorption and modeling study of Np(V) sorption to the mineral goethite from attomolar to micromolar concentrations. 2. Improving the detection capabilities for Thermal Ionization Mass Spectrometry (TIMS) analyses of ultra-trace cesium from environmental samples. Chapter 4 reports a new method which significantly improves the chemical yields, purification, sample processing time, and ultimately, the detection limits for TIMS analyses of femtogram quantities of cesium from a variety of environmental sample matrices. 3. Demonstrating how actinide and cesium concentrations and isotopic ratios from environmental samples can be utilized together to determine a wealth of information including environmental transport mechanisms (e.g. aqueous versus arid transport) and information on the processes which generated the original material. Chapters1, 3 and 5 demonstrate these principles using Pu, Am, Np, and Cs concentrations and isotopic ratios from contaminated soils taken near the Subsurface Disposal Area (SDA) of Idaho National Laboratory (INL) (a low level radioactive waste disposal site in southeastern Idaho).

  15. Corrections to our results for optical nanofiber traps in Cesium

    CERN Document Server

    Ding, D; Choi, K S; Kimble, H J

    2012-01-01

    Several errors in Refs. [1, 2] are corrected related to the optical trapping potentials for a state-insensitive, compensated nanofiber trap for the D2 transition of atomic Cesium. Section I corrects our basic formalism in Ref. [1] for calculating dipole-force potentials. Section II corrects erroneous values for a partial lifetime and a transition wavelength in Ref. [1]. Sections III and IV present corrected figures for various trapping configurations considered in Refs. [1] and [2], respectively.

  16. Electrically switched cesium ion exchange. FY 1997 annual report

    International Nuclear Information System (INIS)

    This paper describes the Electrically Switched Ion Exchange (ESIX) separation technology being developed as an alternative to ion exchange for removing radionuclides from high-level waste. Progress in FY 1997 for specific applications of ESIX is also outlined. The ESIX technology, which combines ion exchange and electrochemistry, is geared toward producing electroactive films that are highly selective, regenerable, and long lasting. During the process, ion uptake and elution can be controlled directly by modulating the potential of an ion exchange film that has been electrochemically deposited onto a high surface area electrode. This method adds little sodium to the waste stream and minimizes the secondary wastes associated with traditional ion exchange techniques. Development of the ESIX process is well underway for cesium removal using ferrocyanides as the electroactive films. Films having selectivity for perrhenate (a pertechnetate surrogate) over nitrate also have been deposited and tested. Based on the ferrocyanide film capacity, stability, rate of uptake, and selectivity shown during performance testing, it appears possible to retain a consistent rate of removal and elute cesium into the same elution solution over several load/unload cycles. In batch experiments, metal hexacyanoferrate films showed high selectivities for cesium in concentrated sodium solutions. Cesium uptake was unaffected by Na/Cs molar ratios of up to 2 x 104 , and reached equilibrium within 18 hours. During engineering design tests using 60 pores per inch, high surface area nickel electrodes, nickel ferrocyanide films displayed continued durability. losing less than 20% of their capacity after 1500 load/unload cycles. Bench-scale flow system studies showed no change in capacity or performance of the ESIX films at a flow rate up to 13 BV/h, the maximum flow rate tested, and breakthrough curves further supported once-through waste processing. 9 refs., 24 figs

  17. Studies on the Separation of Cesium From Fission Products

    Institute of Scientific and Technical Information of China (English)

    QIANLi-juan; ZHANGSheng-dong; GUOJing-ru; CUIAn-zhi; YANGLei; WUWang-suo

    2003-01-01

    135Cs is a long-life fission product. When measuring its thermal cross section, we must separate radiochemical purity cesium from fission products. Except for decontaminating radio- nuclides, others which can be activated must be avoided to come into solution. So ion exchanger is used. Inorganic ion exchangers have received increased attention because of their high resistance to radiation and their very efficient separation of alkali metal ions.

  18. Diode laser spectroscopy of NaD, KD, RbD, and CsD: determination of the mass independent parameters and mass scaling coefficients of the alkali metal hydrides

    International Nuclear Information System (INIS)

    The infrared spectrum of the monodeuterides of the alkali metals, sodium, potassium, rubidium, and cesium have been measured with a nominal accuracy of ±0.001 cm-1 using a diode laser spectrometer. Spectral lines of both the fundamental and the first hot band were observed for all the deuterides except RbD where only the fundamental was measured. The accuracy of previously published data on KH was also improved. Combination of these new data with similar results obtained previously for the equivalent monohydrides allowed the determination of a set of mass-independent parameters and mass-scaling coefficients for the hydrides of all of the alkali metals. This has allowed the relative magnitudes of the parameters to be compared for the first time. The results indicate that non-adiabatic effects are most prevalent in CsH. (orig.)

  19. Extraction of rubidium and cesium from micas following sulfate-extraction technology

    International Nuclear Information System (INIS)

    Results are presented of semicommercial tests of procedure of rubidium and cesium extraction from micas. Micas has been processed by the 40% solution of sulphuric acid at boiling temperature. Separate extraction of cesium and rubidium from the solution with arylalkylsubstituted phenol has been conducted after alum crystallization and decomposition by lime. Pure rubidium carbonate and technical cesium carbonate with their 80 and 95% extraction, respectively, are prepared

  20. Investigations of the method of sodium decontamination from cesium and tritium aiming its utilization or disposal

    International Nuclear Information System (INIS)

    Effective methods of removing cesium and tritium from sodium are submitted. It is shown, that the cleaning from cesium with consecutive use of portions of carbon materials will allow on the orders to reduce amount of sorbent, in which is concentrated cesium. For cleaning from tritium technological process with use of a cold trap and special dosage hydrogen in sodium is offered. The data on required time of cleaning and depth of cleaning at various capacity of hydrogen source are given. (author)

  1. Test procedures and instructions for Hanford complexant concentrate supernatant cesium removal using CST

    Energy Technology Data Exchange (ETDEWEB)

    Hendrickson, D.W.

    1997-01-08

    This document provides specific test procedures and instructions to implement the test plan for the preparation and conduct of a cesium removal test, using Hanford Complexant Concentrate supernatant liquor from tank 241-AN-107, in a bench-scale column. The cesium sorbent to be tested is crystalline silicotitanate. The test plan for which this provides instructions is WHC-SD-RE-TP-023, Hanford Complexant Concentrate Supernatant Cesium Removal Test Plan.

  2. Test procedures and instructions for Hanford tank waste supernatant cesium removal

    Energy Technology Data Exchange (ETDEWEB)

    Hendrickson, D.W., Westinghouse Hanford

    1996-05-31

    This document provides specific test procedures and instructions to implement the test plan for the preparation and conduct of a cesium removal test using Hanford Double-Shell Slurry Feed supernatant liquor from tank 251-AW-101 in a bench-scale column.Cesium sorbents to be tested include resorcinol-formaldehyde resin and crystalline silicotitanate. The test plan for which this provides instructions is WHC-SD-RE-TP-022, Hanford Tank Waste Supernatant Cesium Removal Test Plan.

  3. FEASIBILITY OF RECYCLING PLUTONIUM AND MINOR ACTINIDES IN LIGHT WATER REACTORS USING HYDRIDE FUEL

    International Nuclear Information System (INIS)

    The objective of this DOE NERI program sponsored project was to assess the feasibility of improving the plutonium (Pu) and minor actinide (MA) recycling capabilities of pressurized water reactors (PWRs) by using hydride instead of oxide fuels. There are four general parts to this assessment: (1) Identifying promising hydride fuel assembly designs for recycling Pu and MAs in PWRs; (2) Performing a comprehensive systems analysis that compares the fuel cycle characteristics of Pu and MA recycling in PWRs using the promising hydride fuel assembly designs identified in Part 1 versus using oxide fuel assembly designs; (3) Conducting a safety analysis to assess the likelihood of licensing hydride fuel assembly designs; and (4) Assessing the compatibility of hydride fuel with cladding materials and water under typical PWR operating conditions Hydride fuel was found to offer promising transmutation characteristics and is recommended for further examination as a possible preferred option for recycling plutonium in PWRs

  4. FEASIBILITY OF RECYCLING PLUTONIUM AND MINOR ACTINIDES IN LIGHT WATER REACTORS USING HYDRIDE FUEL

    Energy Technology Data Exchange (ETDEWEB)

    Greenspan, Ehud; Todreas, Neil; Taiwo, Temitope

    2009-03-10

    The objective of this DOE NERI program sponsored project was to assess the feasibility of improving the plutonium (Pu) and minor actinide (MA) recycling capabilities of pressurized water reactors (PWRs) by using hydride instead of oxide fuels. There are four general parts to this assessment: 1) Identifying promising hydride fuel assembly designs for recycling Pu and MAs in PWRs 2) Performing a comprehensive systems analysis that compares the fuel cycle characteristics of Pu and MA recycling in PWRs using the promising hydride fuel assembly designs identified in Part 1 versus using oxide fuel assembly designs 3) Conducting a safety analysis to assess the likelihood of licensing hydride fuel assembly designs 4) Assessing the compatibility of hydride fuel with cladding materials and water under typical PWR operating conditions Hydride fuel was found to offer promising transmutation characteristics and is recommended for further examination as a possible preferred option for recycling plutonium in PWRs.

  5. Formation and growth of hydride blisters in Zr-2.5Nb pressure tubes

    International Nuclear Information System (INIS)

    Hydride blisters were formed on the outer surface of Zr-2.5Nb pressure tube by a nonuniform steady thermal diffusion process. A thermal gradient was applied to the pressure tube with a heat bath kept at a temperature of 415 .deg. C and an aluminum cold finger cooled with flowing water of 15 .deg. C. Optical microscopy and three-dimensional laser profilometry were used to characterize the hydride blisters with different hydrogen concentrations and thermal diffusion time. Hydride blisters were expected to start at a hydrogen concentration of 30 - 70 ppm and a thermal diffusion time of 4 - 6x105 sec. The hydride blister size increases with higher hydrogen concentrations and longer thermal diffusion time. Some of the samples revealed cracks on the hydride blisters. The ratio of hydride blister depth to height was estimated as approximately 8:1

  6. Molecular early main group metal hydrides: synthetic challenge, structures and applications.

    Science.gov (United States)

    Harder, Sjoerd

    2012-11-25

    Within the general area of early main group metal chemistry, the controlled synthesis of well-defined metal hydride complexes is a rapidly developing research field. As group 1 and 2 metal complexes are generally highly dynamic and lattice energies for their [MH](∞) and [MH(2)](∞) salts are high, the synthesis of well-defined soluble hydride complexes is an obvious challenge. Access to molecular early main group metal hydrides, however, is rewarding: these hydrocarbon-soluble metal hydrides are highly reactive, have found use in early main group metal catalysis and are potentially also valuable molecular model systems for polar metal hydrides as a hydrogen storage material. The article focusses specifically on alkali and alkaline-earth metal hydride complexes and discusses the synthetic challenge, molecular structures, reactivity and applications. PMID:23012695

  7. MODELING RESULTS FROM CESIUM ION EXCHANGE PROCESSING WITH SPHERICAL RESINS

    Energy Technology Data Exchange (ETDEWEB)

    Nash, C.; Hang, T.; Aleman, S.

    2011-01-03

    Ion exchange modeling was conducted at the Savannah River National Laboratory to compare the performance of two organic resins in support of Small Column Ion Exchange (SCIX). In-tank ion exchange (IX) columns are being considered for cesium removal at Hanford and the Savannah River Site (SRS). The spherical forms of resorcinol formaldehyde ion exchange resin (sRF) as well as a hypothetical spherical SuperLig{reg_sign} 644 (SL644) are evaluated for decontamination of dissolved saltcake wastes (supernates). Both SuperLig{reg_sign} and resorcinol formaldehyde resin beds can exhibit hydraulic problems in their granular (nonspherical) forms. SRS waste is generally lower in potassium and organic components than Hanford waste. Using VERSE-LC Version 7.8 along with the cesium Freundlich/Langmuir isotherms to simulate the waste decontamination in ion exchange columns, spherical SL644 was found to reduce column cycling by 50% for high-potassium supernates, but sRF performed equally well for the lowest-potassium feeds. Reduced cycling results in reduction of nitric acid (resin elution) and sodium addition (resin regeneration), therefore, significantly reducing life-cycle operational costs. These findings motivate the development of a spherical form of SL644. This work demonstrates the versatility of the ion exchange modeling to study the effects of resin characteristics on processing cycles, rates, and cold chemical consumption. The value of a resin with increased selectivity for cesium over potassium can be assessed for further development.

  8. Transition of cesium in food chains [after Chernobyl catastrophe

    International Nuclear Information System (INIS)

    An investigation of 25,000 samples of foodstuffs and feedstuffs in Czechoslovakia, contaminated by fall-out cesium after the accident in the Chernobyl nuclear power plant, performed from May 5, 1986 to March 31, 1988, revealed that both the values of cesium transfer-factors in food--animal tissues--milk transitions and the values of biological half-life of cesium are functions of internal and external conditions of contamination. Organism individuality as the main internal condition causes the variance of about +/- 50% of the mean value of the respective transfer-factor. Through the external conditions, mainly the environmental contamination level, type of ingested food and time of ingestion, the mean values of transfer-factors are influenced up to 500%, e.g. to the value of 0.5. But this value converges with growing up contamination of food and environment to the limit of 0.3. The first two to three biological half-lives after the last ingestion of contaminated food are up to ten-times shorter than those at stabilized state

  9. Cesium transfer to agricultural crops for three years after Chernobyl

    International Nuclear Information System (INIS)

    In 1986 about 50 farms in the fallout region were selected for sampling at fixed sites of the soil surface layer and of the grassland and grain crops to come. The aim was to cover the different soil types and the farming practices of the region during studies on the transfer levels and on the change with time in transfer of cesium to the crops. It was found that the transfer level, as expected, was much higher for the grassland than for the grain crops. However, within both groups of considerable variation in the transfer level for the same year as measured by the transfer factors has occurred. For the former crops it can be concluded that the transfer factor during year 1 depends on the interception capacity of the plant cover and on the dilution by growth i.e on soil fertility and on fertilization level. In the following years the cesium TF-value for the grass cover was reduced by a factor from 2 to about 10. The reduction rate differed above all between the organic soils and the mineral soils and should largely depend on the type of the grass cover, on the different cesium fixing capacities of the two soil groups and on the potassium fertilization level. On ploughed land the transfer by root uptake to grain crops was about one magnitude lower than the transfer to the hey crops. (orig.)

  10. Example of cesium sorption database in natural minerals

    International Nuclear Information System (INIS)

    In the database of the National Institute for Materials Science (MatNavi), the adsorption data of cesium, strontium, and iodine have been published. Among these data, the authors picked up the data of cesium adsorption against natural ores, which were measured and compiled by the authors, graphically expressed them for clarifying the overall trends, and described each mineral’s adsorption characteristics and future challenges. The partition coefficients for the following minerals are compiled: bentonite, acid clay, montmorillonite, beidellite, vermiculite, illite, mordenite, zeolite, etc. Many of the recorded data in MatNavi are the data obtained in the systems without existence of a large amount of competing ions. On the other hand, in the accumulated water at the Fukushima Daiichi Nuclear Power Station, competing ions due to seawater are contained. In the immersion liquid of incineration fly ash and the immersion liquid of plants/vegetation, too, competing ions are considered to be contained. Accumulation of adsorption data under different solution conditions are considered important. In addition, the concentrations of radioactive cesium in decontamination target are lower values by 5-7 orders, compared with the lower limit of 0.01 ppm in the existing data. In face of experiments, the influence of adsorption to containers and filters cannot be neglected. (A.O.)

  11. On the high-pressure superconducting phase in platinum hydride

    Science.gov (United States)

    Szczȩśniak, D.; Zemła, T. P.

    2015-08-01

    Motivated by the ambiguous experimental data for the superconducting phase in silane (SiH4), which may originate from platinum hydride (PtH), we provide a theoretical study of the superconducting state in the latter alloy. The quantitative estimates of the thermodynamics of PtH at 100 GPa are given for a wide range of Coulomb pseudopotential values ({μ }*) within the Eliashberg formalism. The obtained critical temperature value ({T}{{C}}\\in for {μ }*\\in ) agrees well with the experimental TC for SiH4, which may be ascribed to PtH. Moreover, the calculated characteristic thermodynamic ratios exceed the predictions of the Bardeen-Cooper-Schrieffer theory, implying the occurrence of strong-coupling and retardation effects in PtH. We note that our results may be of high relevance for future theoretical and experimental studies on hydrides.

  12. X-ray photoemission spectroscopy study of zirconium hydride

    International Nuclear Information System (INIS)

    X-ray photoemission spectroscopy (XPS) measurements are reported for ZrH/sub 1.65/ and Zr metal. The valence-band measurements are compared with available band-theory density-of-states calculations for the metal and hydride. The hydride spectrum differs significantly from the metal spectrum. Most important, a strong peak associated with hydrogen s electrons appears approximately 7 eV below the Fermi level. XPS measurements of Zr 4p core levels show a binding-energy shift of 1 eV between Zr metal and ZrH/sub 1.65/. It is argued that this shift results from charge readjustment in the vicinity of the Zr site. With the addition of hydrogen, net charge must be transferred from the Zr site to the hydrogen site. A charge-density analysis based on simplified cluster calculations is presented

  13. Effects of metastability on hydrogen sorption in fluorine substituted hydrides

    Energy Technology Data Exchange (ETDEWEB)

    Pinatel, E.R.; Corno, M.; Ugliengo, P.; Baricco, M., E-mail: marcello.baricco@unito.it

    2014-12-05

    Highlights: • Fluorine substitution in simple metal hydrides has been modelled. • The stability of the MH{sub (1−x)}F{sub x} solid solutions has been discussed. • Conditions for reversibility of sorption reactions have been suggested. - Abstract: In this work ab initio calculations and Calphad modelling have been coupled to describe the effect of fluorine substitution on the thermodynamics of hydrogenation–dehydrogenation in simple hydrides (NaH, AlH{sub 3} and CaH{sub 2}). These example systems have been used to discuss the conditions required for the formation of a stable hydride–fluoride solid solution necessary to obtain a reversible hydrogenation reaction.

  14. Hydride precipitation in zirconium studied by pendulum techniques

    International Nuclear Information System (INIS)

    Measurements of the precipitation peak, the autotwisting strain and the properties of hydride dislocations have been used to map the hydrogen terminal solid solubility boundary in polycrystalline samples and a single-crystal sample of α-zirconium. A low-frequency torsion pendulum was employed for some of the measurements and a low-frequency flexure pendulum for others. These pendulum techniques were successful in extending measurements of the hydrogen terminal solid solubility boundary in α-zirconium to the relatively low hydrogen concentration range 2 to 50 μg/g of technological interest in the nuclear industry. In addition, the results were used to obtain qualitative and quantitative information about the stress dependence of the hydrogen terminal solid solubility boundary and the kinetics of hydride precipitation or dissolution in response to a step change in the applied stress

  15. Detecting low concentrations of plutonium hydride with magnetization measurements

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jae Wook; Mun, E. D.; Baiardo, J. P.; Zapf, V. S.; Mielke, C. H. [National High Magnetic Field Laboratory, MPA-CMMS, Los Alamos National Laboratory (LANL), Los Alamos, New Mexico 87545 (United States); Smith, A. I.; Richmond, S.; Mitchell, J.; Schwartz, D. [Nuclear Material Science Group, MST-16, LANL, Los Alamos, New Mexico 87545 (United States)

    2015-02-07

    We report the formation of plutonium hydride in 2 at. % Ga-stabilized δ-Pu, with 1 at. % H charging. We show that magnetization measurements are a sensitive, quantitative measure of ferromagnetic plutonium hydride against the nonmagnetic background of plutonium. It was previously shown that at low hydrogen concentrations, hydrogen forms super-abundant vacancy complexes with plutonium, resulting in a bulk lattice contraction. Here, we use magnetization, X-ray, and neutron diffraction measurements to show that in addition to forming vacancy complexes, at least 30% of the H atoms bond with Pu to precipitate PuH{sub x} on the surface of the sample with x ∼ 1.9. We observe magnetic hysteresis loops below 40 K with magnetic remanence, consistent with ferromagnetic PuH{sub 1.9}.

  16. Detecting low concentrations of plutonium hydride with magnetization measurements

    International Nuclear Information System (INIS)

    We report the formation of plutonium hydride in 2 at. % Ga-stabilized δ-Pu, with 1 at. % H charging. We show that magnetization measurements are a sensitive, quantitative measure of ferromagnetic plutonium hydride against the nonmagnetic background of plutonium. It was previously shown that at low hydrogen concentrations, hydrogen forms super-abundant vacancy complexes with plutonium, resulting in a bulk lattice contraction. Here, we use magnetization, X-ray, and neutron diffraction measurements to show that in addition to forming vacancy complexes, at least 30% of the H atoms bond with Pu to precipitate PuHx on the surface of the sample with x ∼ 1.9. We observe magnetic hysteresis loops below 40 K with magnetic remanence, consistent with ferromagnetic PuH1.9

  17. Development of a novel metal hydride-air secondary battery

    Energy Technology Data Exchange (ETDEWEB)

    Gamburzev, S.; Zhang, W.; Velev, O.A.; Srinivasan, S.; Appleby, A.J. [Texas A and M University, College Station (United States). Center for Electrochemical Systems and Hydrogen Research; Visintin, A. [Universidad Nacional de La Plata (Argentina). Insituto Nacional de Investigaciones Fisicoquimica Teoricas y Applicadas

    1998-05-01

    A laboratory metal hydride/air cell was evaluated. Charging was via a bifunctional air gas-diffusion electrode. Mixed nickel and cobalt oxides, supported on carbon black and activated carbon, were used as catalysts in this electrode. At 30 mA cm{sup -2} in 6 M KOH, the air electrode potentials were -0.2 V (oxygen reduction) and +0.65 V (oxygen evolution) vs Hg/HgO. The laboratory cell was cycled for 50 cycles at the C/2 rate (10 mA cm{sup -2}). The average discharge/charge voltages of the cell were 0.65 and 1.6 V, respectively. The initial capacity of the metal hydride electrode decreased by about 15% after 50 cycles. (author)

  18. Influence of oxide layer on hydrogen desorption from zirconium hydride

    International Nuclear Information System (INIS)

    Hydrogen desorption from zirconium hydride with hydrogen content of 1.95 H/Zr in He and He-5%O2 atmospheres was studied by thermal desorption spectroscopy (TDS). The morphology, structure and valence states of the oxide layer formed on the surface of zirconium hydride were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). It was found that hydrogen desorption is retarded in the presence of oxygen. Heating in He leads to a large desorption range starting at 500 deg. C while heating in He-5%O2 atmosphere delays decomposition to relatively higher temperature of 525 deg. C. A protective oxide layer composed of monoclinic ZrO2 and small amount of tetragonal ZrO1.88, which acts as a very effective diffusion barrier. The O-H bond was observed in the oxide layer, which is beneficial to fix hydrogen atoms and prevent hydrogen diffusion

  19. Effect of thermo-mechanical cycling on zirconium hydride reorientation studied in situ with synchrotron X-ray diffraction

    Science.gov (United States)

    Colas, Kimberly B.; Motta, Arthur T.; Daymond, Mark R.; Almer, Jonathan D.

    2013-09-01

    The circumferential hydrides normally present in nuclear reactor fuel cladding after reactor exposure may dissolve during drying for dry storage and re-precipitate when cooled under load into a more radial orientation, which could embrittle the fuel cladding. It is necessary to study the rates and conditions under which hydride reorientation may happen in order to assess fuel integrity in dry storage. The objective of this work is to study the effect of applied stress and thermal cycling on the hydride morphology in cold-worked stress-relieved Zircaloy-4 by combining conventional metallography and in situ X-ray diffraction techniques. Metallography is used to study the evolution of hydride morphology after several thermo-mechanical cycles. In situ X-ray diffraction performed at the Advanced Photon Source synchrotron provides real-time information on the process of hydride dissolution and precipitation under stress during several thermal cycles. The detailed study of diffracted intensity, peak position and full-width at half-maximum provides information on precipitation kinetics, elastic strains and other characteristics of the hydride precipitation process. The results show that thermo-mechanical cycling significantly increases the radial hydride fraction as well as the hydride length and connectivity. The radial hydrides are observed to precipitate at a lower temperature than circumferential hydrides. Variations in the magnitude and range of hydride strains due to reorientation and cycling have also been observed. These results are discussed in light of existing models and experiments on hydride reorientation. The study of hydride elastic strains during precipitation shows marked differences between circumferential and radial hydrides, which can be used to investigate the reorientation process. Cycling under stress above the threshold stress for reorientation drastically increases both the reoriented hydride fraction and the hydride size. The reoriented hydride

  20. Ground-state energy and relativistic corrections for positronium hydride

    International Nuclear Information System (INIS)

    Variational calculations of the ground state of positronium hydride (HPs) are reported, including various expectation values, electron-positron annihilation rates, and leading relativistic corrections to the total and dissociation energies. The calculations have been performed using a basis set of 4000 thoroughly optimized explicitly correlated Gaussian basis functions. The relative accuracy of the variational energy upper bound is estimated to be of the order of 2x10-10, which is a significant improvement over previous nonrelativistic results.

  1. Geoneutrinos and Hydridic Earth (or primordially Hydrogen-Rich Planet)

    OpenAIRE

    Bezrukov, L.; Sinev, V.

    2014-01-01

    Geoneutrino is a new channel of information about geochemical composition of the Earth. We alnalysed here the following problem. What statistics do we need to distinguish between predictions of Bulk Silicate Earth model and Hydridic Earth model for Th/U signal ratio? We obtained the simple formula for estimation of error of Th/U signal ratio. Our calculations show that we need more than $22 kt \\cdot year$ exposition for Gran-Sasso underground laboratory and Sudbury Neutrino Observatory. We ne...

  2. Scanning electron microscope techniques for studying Zircaloy corrosion and hydriding

    International Nuclear Information System (INIS)

    A procedure has been developed for preparing scanning electron microscope (SEM) samples of irradiated or unirradiated Zircaloy, suitable for oxide layer imaging, hydride concentration and morphology determination, and X-ray microanalysis (EPMA). The area fraction of the hydride phase is determined by image analysis of backscattered electron images (BEI). Measurements performed on unirradiated laboratory-hydrided samples, as well as cladding samples from pressurized water reactor (PWR) fuel irradiated to a burnup of about 40 MWd/kg U, gave good agreement with hot extraction hydrogen analysis over a wide range of hydrogen concentrations, based on the assumption that all the hydrogen i present as the δ-phase hydride. The local hydrogen concentration can be determined quantitatively with a spatial resolution of less than 100μm. This capability was used to determine the radial hydrogen concentration profiles across the cladding wall for PWR samples with different total hydrogen contents, surface oxide thicknesses, and local heat rating. The results indicated that the hydrogen concentration profile was essentially flat (uniform) across the wall thickness for the samples with a low total hydrogen content (∼200 ppm) or a negligible radial heat flux (plenum), while the samples from fueled sections with >200 ppm or a negligible radial heat flux (plenum), while the samples from fueled sections with >200 ppm H had a steep increase in the hydrogen concentration close to the outer surface. Analysis of a longitudinal section showed peak hydrogen concentrations opposite pellet interfaces a factor of two higher than in the mid-pellet region

  3. Inelastic neutron scattering from amorphous hydride of Zr2Pd

    International Nuclear Information System (INIS)

    Time-of-flight inelastic neutron scattering data was obtained on hydrided Zr2Pd metallic glass using the Crystal Analyzer Spectrometer at the Los Alamos pulsed spallation neutron source. Energy transfers from about 40 MeV to several hundred MeV were obtained with sufficiently good statistics and signal to noise ratio to show the second harmonic as well as the fundamental hydrogen optic mode

  4. Thermomechanics of hydrogen storage in metallic hydrides: modeling and analysis

    Czech Academy of Sciences Publication Activity Database

    Roubíček, Tomáš; Tomassetti, G.

    2014-01-01

    Roč. 19, č. 7 (2014), s. 2313-2333. ISSN 1531-3492 R&D Projects: GA ČR GA201/09/0917 Institutional support: RVO:61388998 Keywords : metal-hydrid phase transformation * hydrogen diffusion * swelling Subject RIV: BA - General Mathematics Impact factor: 0.768, year: 2014 http://aimsciences.org/journals/pdfs.jsp?paperID=10195&mode=full

  5. Dendritic surface morphology of palladium hydride produced by electrolytic deposition

    International Nuclear Information System (INIS)

    Conventional and high-resolution electron microscopic studies of electrolytically-deposited palladium hydride reveal a fascinating variety of surface profile morphologies. The observations provide direct information concerning the surface structure of palladium electrodes and the mechanism of electrolytic deposition of palladium black. Both classical electrochemical mechanisms and recent 'modified diffusion-limited-aggregation' computer simulations are discussed in comparison with the experimental results. 13 refs., 9 figs

  6. The calculated rovibronic spectrum of scandium hydride, ScH

    OpenAIRE

    Lodi, Lorenzo; Yurchenko, Sergei N.; Tennyson, Jonathan

    2015-01-01

    The electronic structure of six low-lying electronic states of scandium hydride, $X\\,{}^{1}\\Sigma^+$, $a\\,{}^{3}\\Delta$, $b\\,{}^{3}\\Pi$, $A\\,{}^{1}\\Delta$ $c\\,{}^{3}\\Sigma^+$, and $B\\,{}^{1}\\Pi$, is studied using multi-reference configuration interaction as a function of bond length. Diagonal and off-diagonal dipole moment, spin-orbit coupling and electronic angular momentum curves are also computed. The results are benchmarked against experimental measurements and calculations on atomic scan...

  7. Hydrogen storage materials and metal hydride-Ni batteries

    International Nuclear Information System (INIS)

    The hydrogen storage alloy is the key active material in metal hydride-Ni (MH-Ni) batteries. A brief review of hydrogen storage negative electrode materials including misch-nickel-based alloys, Laves phase alloys, magnesium-based alloys, vanadium-based solid solutions and nanotubes is presented. Current problems that need to be solved are mentioned. In addition, recent developments of MH/Ni-batteries with high power and energy are introduced

  8. Hydride effect on the tensile properties of HANA-4 alloy

    International Nuclear Information System (INIS)

    KAERI has developed some Zr-based new alloys, called HANA alloys, for high burn-up fuel cladding material. The sample specimens of HANA cladding tube material showed good performance in corrosion and creep properties at the irradiation test in Halden test reactor up to 10GW/MtU as well as the un-irradiation tests. Zirconium alloys has been used as nuclear fuel cladding material because they have satisfactory mechanical strength and corrosion resistance. It was reported that zirconium alloys responded abnormally in mechanical behavior over a certain temperature and strain rates. For example, the embrittlement of Zircaloy-4 (Zr-1.5Sn-0.2Fe-0.1Cr) alloy can be increased over 227 ∼ 427 .deg. C due to dynamic strain aging(DSA). The change of mechanical properties of HANA-4(Zr-1.5Nb-0.4Sn-0.2Fe-0.1Cr) alloy from DSA was already studied from room temperature to 500 .deg. C when its specimens had been tested with the strain rate of 1.67x10-2/s and 8.33x10-5/s. When a zirconium alloy is used in a nuclear reactor, hydrides form in it from not only external hydrogen sources such as waterside corrosion, dissolved hydrogen in coolant, water radiolysis but also internal sources such as hydrogen content in fuel pellets and moisture absorbed by the uranium dioxide fuel pellet. Hydrogen embrittlement of zirconium alloys has been extensively studied because hydrides may act as a sudden failure at very low strain. For low and medium hydrogen content, the hydrides crack during tensile loading and accelerate the ductile fracture process. To study the effect of hydride on the mechanical properties of HANA-4 cladding tube which had been finally heat-treated at 470 .deg. C, this research was done with tensile tests as an extension of the prior study

  9. Corrosion and hydridation features of RBMK type reactor technological channels

    International Nuclear Information System (INIS)

    Generalization results, obtained in the course of monitoring the corrosion state and hydridation of RBMK-1000 and RBMK-1500 reactor technological channels (TC) are presented. It is shown, that the corrosion behaviour of TC tube metal in reactors differs notably. Comparison of data on hybridization of RBMK-100 and RBMK-1500 reactor technological tubes allows one to suppose a possibly higher tendency to hydrogen absorption in Zr - 2.5% of Nb alloy under TMT-1 and TMT-2 states

  10. Computational modelling of structure and dynamics in lightweight hydrides

    OpenAIRE

    Aeberhard, Philippe C.; David, William I. F.; Edwards, Peter P.

    2012-01-01

    Hydrogen storage in lightweight hydrides continues to attract significant interest as the lack of a safe and efficient storage of hydrogen remains the major technological barrier to the widespread use of hydrogen as a fuel. The metal borohydrides Ca(BH₄)₂ and LiBH₄ form the subject of this thesis; three aspects of considerable academic interest were investigated by density functional theory (DFT) and molecular dynamics (MD) modelling. (i) High-pressure crystal structures of Ca(BH₄)₂ were pred...

  11. Proximity breakdown of hydrides in superconducting niobium cavities

    OpenAIRE

    Romanenko, A.; Barkov, F.; Cooley, L. D.; Grassellino, A.

    2012-01-01

    Many modern and proposed future particle accelerators rely on superconducting radio frequency cavities made of bulk niobium as primary particle accelerating structures. Such cavities suffer from the anomalous field dependence of their quality factors Q0. High field degradation - so-called high field Q-slope - is yet unexplained even though an empirical cure is known. Here we propose a mechanism based on the presence of proximity-coupled niobium hydrides, which can explain this effect. Further...

  12. Preparation of Modified Kaolin Filler with Cesium and Its Application in Security Paper

    OpenAIRE

    Houssni El-Saied; Samya El-Sherbiny; Omnia Ali; Wafaa El-Saied; Said Rohyem

    2013-01-01

    In this study, cesium was added intentionally during paper manufacture for protecting the papers against forgery and counterfeiting by sorbing cesium ions (Cs+) on kaolin, used as special filler in papermaking. The sorption of cesium from aqueous solution by kaolin was studied as a function of pH, shaking time, cesium initial concentration, and mass of kaolin using batch technique. The results showed that a solution containing 10 mg/L Cs+ and 250 mg of kaolin at pH 6 can be used to modify the...

  13. Mobility of cesium through the Callovo-Oxfordian claystones under partially saturated conditions

    International Nuclear Information System (INIS)

    The diffusion of cesium was studied in an unsaturated core of Callovo-Oxfordian claystone, which is a potential host rock for retrievable disposal of high-level radioactive wastes. In-diffusion laboratory experiments were performed on rock samples with water saturation degrees ranging from 81% to 100%. The analysis of both cesium concentration monitoring in the source reservoir and postmortem cesium rock concentration profile of the samples was carried out using a chemical-transport code where the sorption of cesium was described by a multi-site ion-exchange model. The results showed that cesium exhibited a clear trend related to the saturation degree of the sample. The more dehydrated the rock sample, the slower the decrease of cesium concentration, and the thinner the penetration depth of cesium was. The effective diffusion coefficient (De) for cesium decreased from 18.5 *10-11 m2 s-1 at full-saturation to 0.3 * 10-11 m2 s-1 for the more dehydrated sample. This decrease is almost 1 order of magnitude higher than that for tritiated water (HTO), although a similar behavior could have been expected, since cesium is known to diffuse in the same parts of the pore space as HTO in fully saturated claystones. (authors)

  14. Cesium transport in Four Mile Creek of the Savannah River Plant

    International Nuclear Information System (INIS)

    The behavior of a large radioactive cesium release to a Savannah River Plant (SRP) stream was examined using a stable cesium release to Four Mile Creek. Measurements following the release show that most of the cesium released was transported downstream; however, sorption and desorption decreased the maximum concentration and increased the travel time and duration, relative to a dye tracer, at sampling stations downstream. The study was made possible by the development of an analytical technique using ammonium molybdophosphate and neutron activation that permitted the measurement of stable cesium concentrations as low as 0.2 μg/L

  15. Radioactive cesium dynamics derived from hydrographic observations in the Abukuma River Estuary, Japan.

    Science.gov (United States)

    Kakehi, Shigeho; Kaeriyama, Hideki; Ambe, Daisuke; Ono, Tsuneo; Ito, Shin-Ichi; Shimizu, Yugo; Watanabe, Tomowo

    2016-03-01

    Large quantities of radioactive materials were released into the air and the ocean as a result of the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident, caused by the 2011 Tohoku earthquake and the subsequent major tsunami off the Pacific coast. There is much concern about radioactive contamination in both the watershed of the Abukuma River, which flows through Fukushima Prefecture, and its estuary, where it discharges into the sea in Miyagi Prefecture. We investigated radioactive cesium dynamics using mixing diagrams obtained from hydrographic observations of the Abukuma River Estuary. Particulate radioactive cesium dominates the cesium load in the river, whereas the dissolved form dominates in the sea. As the salinity increased from <0.1 to 0.1-2.3, the mixing diagram showed that dissolved radioactive cesium concentrations increased, because of desorption. Desorption from suspended particles explained 36% of dissolved radioactive cesium in estuarine water. However, the dissolved and particulate radioactive cesium concentrations in the sea decreased sharply because of dilution. It is thought that more than 80% of the discharged particulate radioactive cesium was deposited off the river mouth, where the radioactive cesium concentrations in sediment were relatively high (217-2440 Bq kg(-1)). Radioactive cesium that was discharged to the sea was transported southward by currents driven by the density distribution. PMID:26698826

  16. Laboratory plant for the separation of cesium from waste solutions of the PUREX process

    International Nuclear Information System (INIS)

    A laboratory plant for the separation of cesium from a fission product waste solution of the fuel reprocessing is described. The plant consists of two stages. In the first stage cesium is adsorbed on ammonium molybdatophosphate (AMP). Then the adsorbent is dissolved. From the solution cesium is adsorbed on a cationic ion exchanger in the second stage. Then AMP can be reproduced from this solution. For the elution of cesium in the second stage a NH4NO3 solution (3 m) is used. Flow sheet, construction and the control device of the plant are described and the results of tests with a model solution are given. (author)

  17. Structure of cesium loaded iron phosphate glasses: An infrared and Raman spectroscopy study

    International Nuclear Information System (INIS)

    The structure of cesium loaded iron phosphate glasses (IPG) was investigated using infrared and Raman spectroscopy. The spectra of the cesium doped samples revealed a structural modification of the parent glass owing to the incorporation of cesium. The structural changes could be correlated with the variation observed in the glass transition temperature of these glasses. Increased Cs-mediated cationic cross linking appears to be the reason for the initial rise in glass transition temperature up to 21 mol% Cs2O in IPG; while, breakdown of the phosphate network with increasing cesium content, brings down the glass transition temperature.

  18. Powder production of U-Mo alloy, HMD process (Hydriding- Milling- Dehydriding)

    International Nuclear Information System (INIS)

    Uranium-molybdenum (U-Mo) alloys can be hydrided massively in metastable γ (gamma) phase. The brittle hydride can be milled and dehydrided to acquire the desired size distributions needed for dispersion nuclear fuels. The developments of the different steps of this process called hydriding-milling- dehydriding (HMD Process) are described. Powder production scales for industrial fabrication is easily achieved with conventional equipment, small man-power and low investment. (author)

  19. High Temperature Metal Hydrides as Heat Storage Materials for Solar and Related Applications

    OpenAIRE

    Borislav Bogdanović; Michael Felderhoff

    2009-01-01

    For the continuous production of electricity with solar heat power plants the storage of heat at a temperature level around 400 °C is essential. High temperature metal hydrides offer high heat storage capacities around this temperature. Based on Mg-compounds, these hydrides are in principle low-cost materials with excellent cycling stability. Relevant properties of these hydrides and their possible applications as heat storage materials are described.

  20. High Temperature Metal Hydrides as Heat Storage Materials for Solar and Related Applications

    Directory of Open Access Journals (Sweden)

    Borislav Bogdanović

    2009-01-01

    Full Text Available For the continuous production of electricity with solar heat power plants the storage of heat at a temperature level around 400 °C is essential. High temperature metal hydrides offer high heat storage capacities around this temperature. Based on Mg-compounds, these hydrides are in principle low-cost materials with excellent cycling stability. Relevant properties of these hydrides and their possible applications as heat storage materials are described.

  1. High temperature metal hydrides as heat storage materials for solar and related applications.

    Science.gov (United States)

    Felderhoff, Michael; Bogdanović, Borislav

    2009-01-01

    For the continuous production of electricity with solar heat power plants the storage of heat at a temperature level around 400 degrees C is essential. High temperature metal hydrides offer high heat storage capacities around this temperature. Based on Mg-compounds, these hydrides are in principle low-cost materials with excellent cycling stability. Relevant properties of these hydrides and their possible applications as heat storage materials are described. PMID:19333448

  2. Oxidation of Group 8 transition-Metal Hydrides and Ionic Hydrogenation of Ketones and Aldehydes

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Kjell-Tore

    1996-08-01

    Transition-metal hydrides have received considerable attention during the last decades because of their unusual reactivity and their potential as homogeneous catalysts for hydrogenation and other reactions of organic substrates. An important class of catalytic processes where transition-metal hydrides are involved is the homogeneous hydrogenation of alkenes, alkynes, ketones, aldehydes, arenes and nitro compounds. This thesis studies the oxidation of Group 8 transition-metal hydrides and the ionic hydrogenation of ketones and aldehydes.

  3. Radioactive cesium content in selected food products. Pt. 1. Radioactive cesium content in dried milk (1987-1988)

    International Nuclear Information System (INIS)

    The content of radioactive cesium in dried and dried skimmed milk from selected dairies was double determined. The highest content was found in samples from milk from OSM Siedlce (98 Bq/kg) and skimmed milk from Radzyn Podlaski and Ostroleka, (the former 90, the latter 62 Bq/kg). The lowest level of radioactive cesium was observed in samples from dried milk from Sieradz, Slups, Wrzesnia, Olecko and Elblag (about or below 10 Bq/kg). Although those levels of contamination with radiocesium did not exceed values recommended by FAO they were determined as high for year 1987/88 as compared milk dates from previous 1985 year. (author). 13 refs, 4 tabs

  4. Transparent yttrium hydride thin films prepared by reactive sputtering

    International Nuclear Information System (INIS)

    Research highlights: → Thin films of transparent (semiconducting) and black (metallic) yttrium hydride. → Magnetron sputtering with an yttrium target and hydrogen as a reactive gas. → Optical transmission and reflection resemble β-YH2 (black) and γ-YH3 (transparent). → XRD shows that transparent films have an expanded fcc lattice with a = 5.35 A. → Samples are stable at ambient conditions. - Abstract: Metal hydrides have earlier been suggested for utilization in solar cells. With this as a motivation we have prepared thin films of yttrium hydride by reactive magnetron sputter deposition. The resulting films are metallic for low partial pressure of hydrogen during the deposition, and black or yellow-transparent for higher partial pressure of hydrogen. Both metallic and semiconducting transparent YHx films have been prepared directly in situ without the need of capping layers and post-deposition hydrogenation. Optically the films are similar to what is found for YHx films prepared by other techniques, but the crystal structure of the transparent films differ from the well-known YH3-η phase, as they have an fcc lattice instead of hcp.

  5. Superconductivity of novel tin hydrides (SnnHm) under pressure

    Science.gov (United States)

    Mahdi Davari Esfahani, M.; Wang, Zhenhai; Oganov, Artem R.; Dong, Huafeng; Zhu, Qiang; Wang, Shengnan; Rakitin, Maksim S.; Zhou, Xiang-Feng

    2016-03-01

    With the motivation of discovering high-temperature superconductors, evolutionary algorithm USPEX is employed to search for all stable compounds in the Sn-H system. In addition to the traditional SnH4, new hydrides SnH8, SnH12 and SnH14 are found to be thermodynamically stable at high pressure. Dynamical stability and superconductivity of tin hydrides are systematically investigated. Im2-SnH8, C2/m-SnH12 and C2/m-SnH14 exhibit higher superconducting transition temperatures of 81, 93 and 97 K compared to the traditional compound SnH4 with Tc of 52 K at 200 GPa. An interesting bent H3–group in Im2-SnH8 and novel linear H in C2/m-SnH12 are observed. All the new tin hydrides remain metallic over their predicted range of stability. The intermediate-frequency wagging and bending vibrations have more contribution to electron-phonon coupling parameter than high-frequency stretching vibrations of H2 and H3.

  6. Structural and magnetic properties of DyFe3 hydrides

    International Nuclear Information System (INIS)

    The ternary hydride phases, DyFe3H/sub x/ with x = 1.7, 2.5, and 4.2 all retain the PuNi3 rhombohedral structure of DyFe3 with a maximum volume expansion of 18% for DyFe3H/sub 4.2/. All phases show a preferential expansion parallel to the c0 axis. From bulk magnetization measurements, the Dy-Fe spin compensation temperature is found to decrease linearly from 5450K for DyFe3 to 1500K for DyFe3H/sub 4.2/ with increasing volume of the hydride phases. The 161Dy Moessbauer results for the two Dy sites in the structure indicate a slight reduction occurs in free-ion moment found for DyFe3 in all hydride phases. In addition, the 57Fe Moessbauer data show that the average Fe moment for the five inequivalent Fe sites increases with hydrogen concentration up to x = 2.5

  7. Superconductivity of novel tin hydrides (SnnHm) under pressure

    Science.gov (United States)

    Mahdi Davari Esfahani, M.; Wang, Zhenhai; Oganov, Artem R.; Dong, Huafeng; Zhu, Qiang; Wang, Shengnan; Rakitin, Maksim S.; Zhou, Xiang-Feng

    2016-01-01

    With the motivation of discovering high-temperature superconductors, evolutionary algorithm USPEX is employed to search for all stable compounds in the Sn-H system. In addition to the traditional SnH4, new hydrides SnH8, SnH12 and SnH14 are found to be thermodynamically stable at high pressure. Dynamical stability and superconductivity of tin hydrides are systematically investigated. Im2-SnH8, C2/m-SnH12 and C2/m-SnH14 exhibit higher superconducting transition temperatures of 81, 93 and 97 K compared to the traditional compound SnH4 with Tc of 52 K at 200 GPa. An interesting bent H3–group in Im2-SnH8 and novel linear H in C2/m-SnH12 are observed. All the new tin hydrides remain metallic over their predicted range of stability. The intermediate-frequency wagging and bending vibrations have more contribution to electron-phonon coupling parameter than high-frequency stretching vibrations of H2 and H3. PMID:26964636

  8. Permeation analysis of tritium through the titanium hydride storage vessel

    International Nuclear Information System (INIS)

    A preliminary design of a stainless steel vessel for the long-term storage of hydrogen isotopes has been proposed. The immobilized hydrogen as a titanium hydride could be used in a stainless steel vessel for this application. The vessel as a primary package is designed to form titanium hydride and to contain the hydrogen isotopes and helium-3 produced from the tritium decay. In order to predict against the possibility of a contamination and the deterioration of the mechanical properties, a numerical calculation was carried out for a diffusion analysis of the hydrogen isotopes and helium inside the stainless steel vessel. Numerical results showed that a negligible amount of tritium would be released by a permeation through the vessel wall of a 0.7cm thickness at normal conditions over the entire period of the storage. In the case that the vessel was heated up to a temperature of 600 C for the routine condition of an activation or exothermic hydriding, it would be of little concern regarding a tritium loss or a contamination. However, when the vessel was exposed to a fire condition with a temperature of 800 C, permeation of the hydrogen through the vessel wall resulted in a serious increase in the amount of tritium escaping, in a very short time

  9. The electronic structure of zirconium in hydrided and oxidized states

    International Nuclear Information System (INIS)

    Highlights: • XANES and XPS of zirconium in oxidized and hydrided states were studied. • The variations in the XANES spectra are explained with density functional theory. • Hydrogen preferentially bonds to specific oxygen sites in the monoclinic ZrO2. • The monoclinic ZrO2 offers the strongest barrier against hydriding attack. - Abstract: Valence band energy shifts for pure zirconium and a model zirconium alloy (Zircaloy-4) in oxidized and hydrided states have been investigated with X-ray photoelectron spectroscopy (XPS) and X-ray Absorption Near-Edge Structure (XANES) technique. With XANES, we show that O/H interactions in oxidized Zr can be detected in the near-edge region of O K. Using density functional theory (DFT) simulations, we have determined where H atoms bond in the monoclinic ZrO2 lattice. The preferred stoichiometry is ZrO2:H, but the O-H bond is weak; increasing H causes the H atoms to form H2 molecules rather than O-H bonds. These interactions cause energy shifts in the Zr 3d XPS spectra. The results illustrate the complex processes of hydrogen and oxygen interactions at the Zr surface

  10. Safety aspects of tritium storage in metal hydride form

    International Nuclear Information System (INIS)

    Air or nitrogen ingress accident scenarios into JET tritium storage containers, filled with uranium or intermetallic compound (IMC) hydrides, are discussed based on the experimentally determined kinetics of the reaction of these hydrides with air, O2 and N2. Reaction of uranium with air can occur at room temperature. For the initiation of the reactions of uranium with N2 or of some intermetallic compounds with air, elevated temperatures are required. Temperature rises of the metal hydrides due to air ingress are estimated for various cases. Modern tritium storage containers are protected against air ingress by intermediate and secondary containments which can be either evacuated or filled with inert gas. Therefore, air ingress can only occur due to double failure: failure of secondary containment and process containment at the same time. At JET, the secondary containments are filled with N2. However, even for N2, temperature increases are expected during the ingress into uranium beds (U-beds) for particular scenarios. It is shown that the JET design would not fail in this event. The calculation also shows that the smallest temperature rises during air, O2 or N2 ingress are expected for a getter bed design with free space above the metal getter layer for the gas to flow from inlet to outlet tube. 14 refs., 3 figs., 4 tabs

  11. Modellization of Metal Hydride Canister for Hydrogen Storage

    Directory of Open Access Journals (Sweden)

    Rocio Maceiras

    2015-06-01

    Full Text Available Hydrogen shows very interesting features for its use on-board applications as fuel cell vehicles. This paper presents the modelling of a tank with a metal hydride alloy for on-board applications, which provides good performance under ambient conditions. The metal hydride contained in the tank is Ti0.98Zr0.02V0.43Fe0.09Cr0.05Mn1.5. A two-dimensional model has been performed for the refuelling process (absorption and the discharge process (desorption. For that, individual models of mass balance, energy balance, reaction kinetics and behaviour of hydrogen gas has been modelled. The model has been developed under Matlab / Simulink© environment. Finally, individual models have been integrated into a global model, and simulated under ambient conditions. With the aim to analyse the temperature influence on the state of charge and filling and emptying time, other simulations were performed at different temperatures. The obtained results allow to conclude that this alloy offers a good behaviour with the discharge process under normal ambient conditions. Keywords: Hydrogen storage; metal hydrides; fuel cell; simulation; board applications

  12. Hydrogen Storage using Metal Hydrides in a Stationary Cogeneration System

    International Nuclear Information System (INIS)

    In the frame of the development of a hydrogen production and storage unit to supply a 40 kW stationary fuel cell, a metal hydride storage tank was chosen according to its reliability and high energetic efficiency. The study of AB5 compounds led to the development of a composition adapted to the project needs. The absorption/desorption pressures of the hydride at 75 C (2 / 1.85 bar) are the most adapted to the specifications. The reversible storage capacity (0.95 %wt) has been optimized to our work conditions and chemical kinetics is fast. The design of the Combined Heat and Power CHP system requires 5 kg hydrogen storage but in a first phase, only a 0.1 kg prototype has been realised and tested. Rectangular design has been chosen to obtain good compactness with an integrated plate fin type heat exchanger designed to reach high absorption/desorption rates. In this paper, heat and mass transfer characteristics of the Metal Hydride tank (MH tank) during absorption/desorption cycles are given. (authors)

  13. Neutron diffraction studies of metal hydrides alloys for hydrogen storage

    International Nuclear Information System (INIS)

    In this paper we present results obtained from two different classes of metal hydrides. First, we will discuss the effect of ball milling on the hydrogen storage properties of magnesium hydride. High energy milling of MgD2 produces a nanocrystalline structure made of a mixture of β-MgD2 and the high temperature/high pressure phase γ-MgD2. Neutron powder diffraction showed that the ball-milled β-MgD2 and γ-MgD2 structures are distorted compared to the same phases synthesised at high-pressure and high temperature. The Mg-D bond lengths are modified in β-MgD2. In γ-MgD2 phase, only one bond length is changed. This may be the explanation for the limited amount of γ-MgD2 synthesized by energetic ball milling. The second case is the crystal structure of a new class of metal hydrides, the so called 'Laves phase related BCC solid solution'. From neutron diffraction, we found that two phases are present in the as-cast alloy TiV0.9Mn1.1. One is a BCC solid solution, the other is a C14 Laves phase. We found that in the C14 phase there is a preferential site for titanium atoms while the vanadium and manganese atoms are distributed on the other two sites. (author)

  14. Performance study of a hydrogen powered metal hydride actuator

    Science.gov (United States)

    Mainul Hossain Bhuiya, Md; Kim, Kwang J.

    2016-04-01

    A thermally driven hydrogen powered actuator integrating metal hydride hydrogen storage reactor, which is compact, noiseless, and able to generate smooth actuation, is presented in this article. To test the plausibility of a thermally driven actuator, a conventional piston type actuator was integrated with LaNi5 based hydrogen storage system. Copper encapsulation followed by compaction of particles into pellets, were adopted to improve overall thermal conductivity of the reactor. The operation of the actuator was thoroughly investigated for an array of operating temperature ranges. Temperature swing of the hydride reactor triggering smooth and noiseless actuation over several operating temperature ranges were monitored for quantification of actuator efficiency. Overall, the actuator generated smooth and consistent strokes during repeated cycles of operation. The efficiency of the actuator was found to be as high as 13.36% for operating a temperature range of 20 °C-50 °C. Stress-strain characteristics, actuation hysteresis etc were studied experimentally. Comparison of stress-strain characteristics of the proposed actuator with traditional actuators, artificial muscles and so on was made. The study suggests that design modification and use of high pressure hydride may enhance the performance and broaden the application horizon of the proposed actuator in future.

  15. Air passivation of metal hydride beds for waste disposal

    International Nuclear Information System (INIS)

    One waste acceptance criteria for hydride bed waste disposal is that the bed be non-pyrophoric. Batch-wise air ingress tests were performed which determined the amount of air consumed by a metal hydride bed. A desorbed, 4.4 kg titanium prototype hydride storage vessel (HSV) produced a 4.4 deg.C internal temperature rise upon the first air exposure cycle and a 0.1 deg.C temperature rise upon a second air exposure. A total of 346 sec air was consumed by the bed (0.08 sec per gram Ti). A desorbed, 9.66 kg LaNi4.25Al0.75 prototype storage bed experienced larger temperature rises over successive cycles of air ingress and evacuation. The cycles were performed over a period of days with the bed effectively passivated after the 12. cycle. Nine to ten STP-L of air reacted with the bed producing both oxidized metal and water. (authors)

  16. Multidimensional Chemical Modeling. III. Abundance and excitation of diatomic hydrides

    CERN Document Server

    Bruderer, Simon; Stäuber, P; Doty, Steven D

    2010-01-01

    The Herschel Space Observatory opens the sky for observations in the far infrared at high spectral and spatial resolution. A particular class of molecules will be directly observable; light diatomic hydrides and their ions (CH, OH, SH, NH, CH+, OH+, SH+, NH+). These simple constituents are important both for the chemical evolution of the region and as tracers of high-energy radiation. If outflows of a forming star erode cavities in the envelope, protostellar far UV (FUV; 6 100 K) for water ice to evaporate. If the cavity shape allows FUV radiation to penetrate this hot-core region, the abundance of FUV destroyed species (e.g. water) is decreased. In particular, diatomic hydrides and their ions CH$+, OH+ and NH+ are enhanced by many orders of magnitude in the outflow walls due to the combination of high gas temperatures and rapid photodissociation of more saturated species. The enhancement of these diatomic hydrides is sufficient for a detection using the HIFI and PACS instruments onboard Herschel. The effect...

  17. Radioactive cesium. Dynamics and transport in forestal food-webs; Radioaktivt cesium. Dynamik och transport i skogliga naeringsvaevar

    Energy Technology Data Exchange (ETDEWEB)

    Palo, T.; Nelin, P. [Swedish Univ. of Agricultural Sciences, Umeaa (Sweden). Dept. of Animal Ecology; Bergman, R.; Nylen, T. [FOA NBC Defence, Umeaa (Sweden)

    1995-12-01

    This report summarises results from a radioecological study during 1994-1995 concerning turnover, redistribution and loss of radioactive Cesium (134 and 137) in boreal forest ecosystems, as well as uptake and transfer in important food-chains over moose, vole and vegetation. The basis for this report are 9 publications published 1994-95. These reports are presented in summary form. 9 refs, 17 figs.

  18. Cesium and strontium exchange properties of marsh soils

    International Nuclear Information System (INIS)

    The cesium and strontium exchange properties of some typical marsh soils of the estuary and lower river Weser region were described. Soil samples were taken according to the existing soil maps 1:25000 of Lower Saxony e.g. a “sea marsh soil”. a “brackish marsh soil”, and a “river marsh soil”. The exchange properties were determined by Cs/Ca and Sr/Ca exchange curves (Q/I relations) as generally used in soil potassium research. In addition to the Q/I relations the following investigations were carried out: - Cs and Sr desorption experiments (one time equilibration with Ca++ solutions) - Cs and Sr reexchange experiments (eight times equilibration with water, Ca++, Ba++, and K+ solutions) - the naturally-occuring Cs and Sr contents of the soils including amounts caused by imissions or fallout, respectively - clay mineral composition and swelling of layer silicates due to saturation with Ca++, Sr++, Cs+, and K+ ions. Q/I relations as well as desorption and reexchange experiments indicated strong cesium and low strontium fixation by the soils investigated. This was considered the reason for the stronger transfer of Sr from soil to plants as compared with Cs. Furthermore, the reexchange experiment revealed nearly complete reversibility of the Sr sorption reactions by equilibration with the divalent cations Ca++ and Ba++ and some Sr fixation after treatment with K+ solutions. However, cesium was much better reexchanged by K+ than by Ca++ and Ba++ ions. This led to the conclusion that Cs fixed in interlayer positions of clay minerals could be remobilized by potassium and ammonium fertilization. The naturally-occuring Cs contents of the soils were found to be below the detection limit of the analytical methods used. The contents of naturally-occuring exchangeable Sr, however, was in agreement with the amounts of “labile Sr” as derived from the Sr/Ca exchange curves. Concerning the cesium exchange properties a clear distinction between “sea and river marsh

  19. Effect of the hydrogen content and cooling velocity in the hydrides precipitation in α-zirconium

    International Nuclear Information System (INIS)

    Zirconium specimens containing 50-300 ppm hydrogen have been cooled from the hydrogen solution treatment temperature at different rates by furnace cooling, air cooling and oil quenching. Optical and electron microscopical investigations have revealed grain boundary Δ - hydrides in slowly cooled specimens. At higher cooling rates γ and Δ hydrides have been found precipitated both intergranularly and intragranularly. Grain boundary Δ hydrides have been also observed in oil quenched specimens with 300 ppm hydrogen. Quenched specimens have revealed Widmanstatten and parallel plate type hydride morphologies. (Author)

  20. Measurement and modeling of strain fields in zirconium hydrides precipitated at a stress concentration

    Science.gov (United States)

    Allen, Gregory B.; Kerr, Matthew; Daymond, Mark R.

    2012-11-01

    Hydrogen adsorption into zirconium, as a result of corrosion in aqueous environments, leads to the precipitation of a secondary brittle hydride phase. These hydrides tend to first form at stress concentrations such as fretting flaws or cracks in engineering components, potentially degrading the structural integrity of the component. One mechanism for component failure is a slow crack growth mechanism known as Delayed Hydride Cracking (DHC), where hydride fracture occurs followed by crack arrest in the ductile zirconium matrix. The current work employs both an experimental and a modeling approach to better characterize the effects and behavior of hydride precipitation at such stress concentrations. Strains around stress concentrations containing hydrides were mapped using High Energy X-ray Diffraction (HEXRD). These studies highlighted important differences in the behavior of the hydride phase and the surrounding zirconium matrix, as well as the strain associated with the precipitation of the hydride. A finite element model was also developed and compared to the X-ray strain mapping results. This model provided greater insight into details that could not be obtained directly from the experimental approaches, as well as providing a framework for future modeling to predict the effects of hydride precipitation under varied conditions.

  1. Mechanical characteristics of hydrides in titanium and titanium-palladium alloy

    International Nuclear Information System (INIS)

    With the aim of estimating of stress-strain curve and fracture strain of thin layer hydrides of pure titanium (Gr.1) and titanium-palladium alloy (Gr.17), we utilized dual indentation method and advanced indentation machine equipped with acoustic emission (AE) monitoring system. We first estimated stress-strain curves of two base metals and two hydrides utilizing the dual indentation method. Next we estimated the fracture strain of two hydrides by FEM method using the critical indentation force to cause the Mode-I crack in hydrides during indentation tests. The critical force was correctly determined by waveform analysis of AEs detected during indentation test. The fracture strain of hydride of Gr.1 was estimated as 8.1% and larger than that (4.3%) of Gr.17 hydride. Fracture strains of two hydrides appear to be due to the chemical composition of the hydrides. Gr.1 produced a TiH2 hydride, while Gr.1 did a TiH1.971. (author)

  2. Investigation of Liquid Metal Bonded Hydride Fuels for LWRs - A Review

    International Nuclear Information System (INIS)

    Hydride fuels have been proposed for power production applications in LWRs. The fuel consists of uranium-zirconium hydride pellets clad with Zircaloy tubing. The fuel-cladding gap is filled with a liquid lead-tin- bismuth alloy. Incentives for hydride fuel incorporation into LWRs are briefly reviewed followed by a detailed discussion of material properties, steady-state and transient behaviour, and irradiation effects on hydride fuels. The discussion is based on historical data from the SNAP program and General Atomics' TRIGA reactors and recent research conducted at Universities of Tokyo and California, Berkeley. (author)

  3. Some new techniques in tritium gas handling as applied to metal hydride synthesis

    International Nuclear Information System (INIS)

    A state-of-the-art tritium Hydride Synthesis System (HSS) was designed and built to replace the existing system within the Tritium Salt Facility (TSF) at the Los Alamos National Laboratory. This new hydriding system utilized unique fast-cycling 5.63 mole uranium beds (50.9 g to T2 at 100% loading) and novel gas circulating hydriding furnaces. Tritium system components discussed include fast-cycling uranium beds, circulating gas hydriding furnaces, valves, storage volumes, manifolds, gas transfer pumps, and graphic display and control consoles. Many of the tritium handling and processing techniques incorporated into this system are directly applicable to today's fusion fuel loops

  4. Some new techniques in tritium gas handling as applied to metal hydride synthesis

    International Nuclear Information System (INIS)

    A state-of-the-art tritium Hydriding Synthesis System (HSS) was designed and built to replace the existing system within the Tritium Salt Facility (TSF) at the Los Alamos National Laboratory. This new hydriding system utilizes unique fast-cycling 7.9 mole uranium beds (47.5g of T at 100% loading) and novel gas circulating hydriding furnaces. Tritium system components discussed include fast-cycling uranium beds, circulating gas hydriding furnaces, valves, storage volumes, manifolds, gas transfer pumps, and graphic display and control consoles. Many of the tritium handling and processing techniques incorporated into this system are directly applicable to today's fusion fuel loops. 12 refs., 7 figs

  5. Elastic and inelastic scattering of cesium, cesium iodide, and cesium chloride by argon and xenon in the crossed atomic and molecular beams

    International Nuclear Information System (INIS)

    Velocity and angular distributions of cesium atoms and two cesium halide molecules scattered by rare gas atoms have been measured for the following systems at the indicated initial relative collision energies, anti E: Cs + Ar, anti E = 0.94, 1.29, and 1.85 kcal/mole; Cs + Xe, E = 1.15, 1.91, and 3.10 kcal/mole; Csl + Ar, anti E = 1.06, 1.46, and 2.08 kcal/mole; CsI + Ar, anti E = 1.36, 1.63, and 1.94 kcal/mole; CsI + Xe, anti E = 1.52, 2.52, and 4.09 kcal/mole. At the collision energies indicated the atom-atom scattering can only be elastic. Thus the experiments with those systems can be used for apparatus calibration and a standard of comparison for the diatom-atom experiments. The velocity distributions in the diatom-atom systems are analyzed for the relative contributions of elastic and inelastic scattering

  6. Hydride phase equilibria in V-Ti-Ni alloy membranes

    International Nuclear Information System (INIS)

    Highlights: • V70Ti15Ni15 (at.%) comprises a vanadium solid solution plus NiTi and NiTi2. • Dissolution of Ni and Ti into vanadium solid solution increase critical temperature for BCT β-hydride formation. • Three VSS hydride phase fields were observed: BCC, BCC + BCT, BCT + BCT. • NiTi and NiTi2 phases do not stabilise the alloy against brittle failure. - Abstract: Vanadium is highly permeable to hydrogen which makes it one of the leading alternatives to Pd alloys for hydrogen-selective alloy membrane applications, but it is prone to brittle failure through excessive hydrogen absorption and transitions between the BCC α and BCT β phases. V-Ti-Ni alloys are a prospective class of alloy for hydrogen-selective membrane applications, comprising a highly-permeable vanadium solid solution and several interdendritic Ni-Ti compounds. These Ni-Ti compounds are thought to stabilise the alloy against brittle failure. This hypothesis was investigated through a systematic study of V70Ti15Ni15 by hydrogen absorption and X-ray diffraction under conditions relevant to membrane operation. Dissolved hydrogen concentration in the bulk alloy and component phases, phase identification, thermal and hydrogen-induced expansion, phase quantification and hydride phase transitions under a range of pressures and temperatures have been determined. The vanadium phase passes through three different phase fields (BCC, BCC + BCT, BCT + BCT) during cooling under H2 from 400 to 30 °C. Dissolution of Ni and Ti into the vanadium phase increases the critical temperature for β-hydride formation from <200 to >400 °C. Furthermore, the Ni-Ti phases also exhibit several phase transitions meaning their ability to stabilise the alloy is questionable. We conclude that this alloy is significantly inferior to V with respect to its stability when used as a hydrogen-selective membrane, but the hydride phase transitions suggest potential application for high-temperature hydrogen and thermal energy

  7. Reactivity patterns of transition metal hydrides and alkyls

    International Nuclear Information System (INIS)

    The complex PPN+ CpV(CO)3H- (Cp=eta5-C5H5 and PPN = (Ph3P)2) was prepared in 70% yield and its physical properties and chemical reactions investigated. PPN+ CpV(CO)3H- reacts with a wide range of organic halides. The organometallic products of these reactions are the vanadium halides PPN+[CpV(C)3X]- and in some cases the binuclear bridging hydride PPN+ [CpV(CO)3]2H-. The borohydride salt PPN+[CpV(CO)3BH4]- has also been prepared. The reaction between CpV(CO)3H- and organic halides was investigated and compared with halide reductions carried out using tri-n-butyltin hydride. Results demonstrate that in almost all cases, the reduction reaction proceeds via free radical intermediates which are generated in a chain process, and are trapped by hydrogen transfer from CpV(CO)3H-. Sodium amalgam reduction of CpRh(CO)2 or a mixture of CpRh(CO)2 and CpCo(CO)2 affords two new anions, PPN+ [Cp2Rh3(CO)4]- and PPN+[Cp2RhCo(CO)2]-. CpMo(CO)3H reacts with CpMo(CO)3R (R=CH3,C2H5, CH2C6H5) at 25 to 500C to produce aldehyde RCHO and the dimers [CpMo(CO)3]2 and [CpMo(CO)2]2. In general, CpV(CO)3H- appears to transfer a hydrogen atom to the metal radical anion formed in an electron transfer process, whereas CpMo(CO)3H transfers hydride in a 2-electron process to a vacant coordination site. The chemical consequences are that CpV(CO)3H- generally reacts with metal alkyls to give alkanes via intermediate alkyl hydride species whereas CpMo(CO)3H reacts with metal alkyls to produce aldehyde, via an intermediate acyl hydride species

  8. Cesium-137 inventories in undisturbed areas in different regions of Brazil

    International Nuclear Information System (INIS)

    Cesium-137 is an anthropogenic radionuclide introduced in the environment in the early of 1960s to the end of 1970s. The Cesium-137 has very used to assess soil redistribution in the landscape because this is very tight in the fine soil particles and its movement in the landscape is due to soil redistribution. To use Cesium-137 to assess soil redistribution is need to known the Cesium-137 inventory in an area that not has experimented soil erosion neither soil deposition. So, this work present Cesium-137 inventories in undisturbed areas in different regions of Brazil, from South to Northeast of Brazil. The inventories in these areas represent the variational deposition of Cesium-137 in the whole national territory of Brazil. The inventories of Cesium-137 varied from 200 ± 15 Bq.m-2 for South region to 15 ± 2 Bq.m-2 for Northeast region. Moreover, was verified that the Cesium- 137 inventories depend on latitude and altitude of the area. (author)

  9. Vacuum squeezed light for atomic memories at the D2 cesium line

    CERN Document Server

    Burks, Sidney; Giacobino, Elisabeth; Laurat, Julien; Ortalo, Jérémie; Jia, Xiaojun; Villa, Fabrizio; Chuimmo, Antonino

    2008-01-01

    We report the experimental generation of squeezed light at 852 nm, locked on the Cesium D2 line. 50% of noise reduction down to 50 kHz has been obtained with a doubly resonant optical parametric oscillator operating below threshold, using a periodically-polled KTP crystal. This light is directly utilizable with Cesium atomic ensembles for quantum networking applications

  10. Ionizing mechanisms in a cesium plasma irradiated with a ruby laser

    Science.gov (United States)

    Shimada, K.; Robinson, L. B.

    1975-01-01

    A cesium filled diode--laser plasmadynamic converter was built to investigate the feasibility of converting laser energy to electrical energy at large power levels. Experiments were performed with a pulsed ruby laser to determine the quantity of electrons and cesium ions generated per pulse of laser beam and to determine the output voltage. A current density as high as 200 amp/sq cm from a spot of approximately 1 sq mm area and an open circuit voltage as high as 1.5 volts were recorded. A qualitative theory was developed to explain these results. In the operation of the device, the laser beam evaporates some of the cesium and ionizes the cesium gas. A dense cesium plasma is formed to absorb further the laser energy. Results suggest that the simultaneous absorption of two ruby laser photons by the cesium atoms plays an important role in the initial ionization of cesium. Inverse bremsstrahlung absorption appears to be the dominant mechanism in subsequent processes. Recombinations of electrons and cesium ions appear to compete favorably with the simultaneous absorption of two photons.

  11. Peculiarities of presence of cesium-137 in soil at Azgir test site grounds

    International Nuclear Information System (INIS)

    The granulometric composition of soil and the distribution of cesium-137 by soil fractions at the Azgir test site was determined. The characterization of cesium-137 presence in the layer of the thickness of 1 cm of the surface soil was gave. (author)

  12. Velocity Distribution of Effective Atoms in a Small Optically Pumped Cesium Beam Frequency Standard

    Institute of Scientific and Technical Information of China (English)

    CHEN Jingbiao; WANG Fengzhi; YANG Donghai; WANG YiQiu

    2001-01-01

    In this paper, the velocity distribution of effective atoms in a small optically pumped cesium beam frequency standard has been achieved from the Fourier transforms of the experimentally recorded Ramsey patterns. The result fits well with the theoretical calculation. The second order Doppler shift correction of the small cesium atomic clock is obtained from the velocity distribution of effective atoms.

  13. Cesium-134 and cesium-137 in honey bees and cheese samples collected in the U.S. after the Chernobyl accident

    International Nuclear Information System (INIS)

    As a result of the Chernobyl accident on April 25, 1986, possible radioactive contamination of honey bees and cheese sampled in several areas of the United States were measured. Of bees collected in May and June of 1986 in both Oregon and New York, only those from Oregon showed detectable levels of cesium-134 (T1/2 = 2.05 years), a radionuclide which would have originated from the Chernobyl incident. Cheese produced in Oregon and New York before the accident showed only cesium-137 (T1/2 = 30.23 years) but cheese produced afterwards (May and September, 1986) in Oregon contained cesium-134. Cheese produced in Ohio and California at the time of the accident and thereafter contained only cesium-137. In general, the levels of radioactivity were higher in the West coast samples as compared to those taken in the East. The levels of radioactivity detected were considered to be toxicologically of no consequence. (author)

  14. Cesium ion exchange using actual waste: Column size considerations

    International Nuclear Information System (INIS)

    It is presently planned to remove cesium from Hanford tank waste supernates and sludge wash solutions using ion exchange. To support the development of a cesium ion exchange process, laboratory experiments produced column breakthrough curves using wastes simulants in 200 mL columns. To verify the validity of the simulant tests, column runs with actual supernatants are being planned. The purpose of these actual waste tests is two-fold. First, the tests will verify that use of the simulant accurately reflects the equilibrium and rate behavior of the resin compared to actual wastes. Batch tests and column tests will be used to compare equilibrium behaviors and rate behaviors, respectively. Second, the tests will assist in clarifying the negative interactions between the actual waste and the ion exchange resin, which cannot be effectively tested with simulant. Such interactions include organic fouling of the resin and salt precipitation in the column. These effects may affect the shape of the column breakthrough curve. The reduction in column size also may change the shape of the curve, making the individual effects even more difficult to sort out. To simplify the evaluation, the changes due to column size must be either understood or eliminated. This report describes the determination of the column size for actual waste testing that best minimizes the effect of scale-down. This evaluation will provide a theoretical basis for the dimensions of the column. Experimental testing is still required before the final decision can be made. This evaluation will be confined to the study of CS-100 and R-F resins with NCAW simulant and to a limited extent DSSF waste simulant. Only the cesium loading phase has been considered

  15. Sorption of iodine, chlorine, technetium and cesium in soil

    International Nuclear Information System (INIS)

    The safety assessment of final disposal of spent nuclear fuel will include an estimate for the behavior of waste nuclides in the biosphere. As a part of this estimate also the sorption of radioactive iodine, chlorine, technetium and cesium in soil is to be considered. The chemistry and the sorption of these radionuclides in soils are described in this literature survey. Behavior of I-129, Cl-36 and Tc-99 in the environment is of great interest because of their long half-lives and relatively high mobilities. The importance of Cs-135 arises from its high content in spent nuclear fuel and long physical half-life, even though it is considered relatively immobile in soil. Factors affecting the migration and sorption of radionuclides in soils can be divided into elemental and soil specific parameters. The most important elemental factor is the speciation of the element, which is influenced by the soil redox potential, pH and complex forming ligands. Soil micro-organisms can either serve as sorbents for radionuclides or affect their speciation by altering the prevailing soil redox conditions. Soil organic matter content and mineral properties have a marked influence on the retention of radionuclides. The sorption of anionic radionuclides such as I-, Cl- and TcO4 - is pronounced in the presence of organic matter. Clay minerals are known to bound cesium effectively. The effect of speciation of radioactive iodine, chlorine, technetium and cesium in soil is considered in this study, as well as the effect of soil micro-organisms, organic matter and mineral properties. (orig.)

  16. Cesium Eluate Evaporation Solubility and Physical Property Behavior

    International Nuclear Information System (INIS)

    The baseline flowsheet for low activity waste (LAW) in the Hanford River Protection Project (RPP) Waste Treatment Plant (WTP) includes pretreatment of supernatant by removing cesium using ion exchange. When the ion exchange column is loaded, the cesium will be eluted with a 0.5M nitric acid (HNO3) solution to allow the column to be conditioned for re-use. The cesium eluate solution will then be concentrated in a vacuum evaporator to minimize storage volume and recycle HNO3. To prevent the formation of solids during storage of the evaporator bottoms, criteria have been set for limiting the concentration of the evaporator product to 80 percent of saturation at 25 degrees C. A fundamental element of predicting evaporator product solubility is to collect data that can be used to estimate key operating parameters. The data must be able to predict evaporator behavior for a range of eluate concentrations that are evaporated to the point of precipitation. Parameters that were selected for modeling include solubility, density, viscosity, thermal conductivity, and heat capacity. Of central importance is identifying the effect of varying feed components on overall solubility. The point of solubility defines the upper limit for eluate evaporation operations and liquid storage. The solubility point also defines those chemical compounds that have the greatest effects on physical properties. Third, solubility behavior identifies intermediate points where physical property data should be measured for the database. Physical property data (density, viscosity, thermal conductivity, and heat capacity) may be an integral part of tracking evaporator operations as they progress toward their end point. Once the data have been collected, statistical design software can develop mathematical equations that estimate solubility and other physical properties

  17. Cesium-137 inventory of the undisturbed soil areas in the Londrina Region, Parana, Brazil

    International Nuclear Information System (INIS)

    Cesium-137 is an artificial radionuclide introduced in the environment through the radioactive fallout of the superficial tests of nuclear weapons. The cesium-137 deposition occurred to middles of the 1980-decade and, due to the Chernobyl accident, great part of Europe had a additional fallout of cesium-137. The contaminations of this accident do not have reached Southern Hemisphere. Cesium-137 is an alkaline metal, high electropositive, that in contact with the soil is strongly adsorbed to the clay in the FES (Frayed Edge Sites) and RES (Regular Edge Sites) positions, and it movement by chemical processes in the soil is insignificant. Because of this, cesium-137 became a good soil marker, and its movement is related to the soil movement particles, so that the cesium-137 have been used in the study of the soil redistribution processes, as a tool of quantifying the rates of soil losses and gain. To use this methodology, it is necessary the knowledge of the reference inventory of cesium-137, that is given as function of the total concentration of cesium-137 deposited in an area by the radioactive fallout. If a sampling point presents less cesium-137 than the reference inventory, this point is considered a point with soil loss; otherwise, the point is considered a point with soil deposition. To evaluate the cesium-137 inventory in the Londrina region, four areas of the undisturbed soil were sampling in grid of 3x3, with a distance of 9 meters among the points. Of these four sampling areas, three areas were of native forest (labeled Mata1, Mata2 and Mata UEL), and one was a pasture area. Cesium-137 inventory was 223 ± 41 Bq m-2, 240 ± 65 Bq m-2 and 305 ± 36 Bq m-2 for Mata UEL, Mata1 and Mata2, respectively, and of 211 ± 28 Bq m-2 for the native pasture. Considering the deviation in each value, it is not possible to conclude that there are differences among the values of cesium-137 inventory, so that the average reference inventory of cesium-137 for the Londrina

  18. Characterization of quantum efficiency and robustness of cesium-based photocathodes

    Science.gov (United States)

    Montgomery, Eric J.

    High quantum efficiency, robust photocathodes produce picosecond-pulsed, high-current electron beams for photoinjection applications like free electron lasers. In photoinjectors, a pulsed drive laser incident on the photocathode causes photoemission of short, dense bunches of electrons, which are then accelerated into a relativistic, high quality beam. Future free electron lasers demand reliable photocathodes with long-lived quantum efficiency at suitable drive laser wavelengths to maintain high current density. But faced with contamination, heating, and ion back-bombardment, the highest efficiency photocathodes find their delicate cesium-based coatings inexorably lost. In answer, the work herein presents careful, focused studies on cesium-based photocathodes, particularly motivated by the cesium dispenser photocathode. This is a novel device comprised of an efficiently photoemissive, cesium-based coating deposited onto a porous sintered tungsten substrate, beneath which is a reservoir of elemental cesium. Under controlled heating cesium diffuses from the reservoir through the porous substrate and across the surface to replace cesium lost to harsh conditions---recently shown to significantly extend the lifetime of cesium-coated metal cathodes. This work first reports experiments on coated metals to validate and refine an advanced theory of photoemission already finding application in beam simulation codes. Second, it describes a new theory of photoemission from much higher quantum efficiency cesium-based semiconductors and verifies its predictions with independent experiment. Third, it investigates causes of cesium loss from both coated metal and semiconductor photocathodes and reports remarkable rejuvenation of full quantum efficiency for contaminated cesium-coated surfaces, affirming the dispenser prescription of cesium resupply. And fourth, it details continued advances in cesium dispenser design with much-improved operating characteristics: lower temperature

  19. Hydride precipitation and its influence on mechanical properties of notched and unnotched Zircaloy-4 plates

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhiyang, E-mail: zw603@uowmail.edu.au [Faculty of Engineering, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522 (Australia); The Bragg Institute, Australian Nuclear Science and Technology Organisation, New Illawarra Road, Lucas Heights, NSW 2234 (Australia); Garbe, Ulf [The Bragg Institute, Australian Nuclear Science and Technology Organisation, New Illawarra Road, Lucas Heights, NSW 2234 (Australia); Li, Huijun [Faculty of Engineering, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522 (Australia); Harrison, Robert P.; Toppler, Karl [The Institute of Materials Engineering, Australian Nuclear Science and Technology Organisation, New Illawarra Road, Lucas Heights, NSW 2234 (Australia); Studer, Andrew J. [The Bragg Institute, Australian Nuclear Science and Technology Organisation, New Illawarra Road, Lucas Heights, NSW 2234 (Australia); Palmer, Tim [The Institute of Materials Engineering, Australian Nuclear Science and Technology Organisation, New Illawarra Road, Lucas Heights, NSW 2234 (Australia); Planchenault, Guillaume [Electricite De France, 6 Avenue Montaigne, 93192 Noisy Le Grand Cédex (France)

    2013-05-15

    The hydride formation and its influence on the mechanical performance of hydrided Zircaloy-4 plates containing different hydrogen contents were studied at room temperature. For the unnotched plate samples with the hydrogen contents ranging from 25 to 850 wt. ppm, the hydrides exerted an insignificant effect on the tensile strength, while the ductility was severely degraded with increasing hydrogen content. The fracture mode and degree of embrittlement were strongly related to the hydrogen content. When the hydrogen content reached a level of 850 wt. ppm, the plate exhibited negligible ductility, resulting in almost completely brittle behavior. For the hydrided notched plate, the tensile stress concentration associated with the notch tip facilitated the hydride accumulation at the region near the notch tip and the premature crack propagation through the hydride fracture during hydriding. The final brittle through-thickness failure for this notched sample was mainly attributed to the formation of a continuous hydride network on the thickness section and the obtained very high hydrogen concentration (estimated to be 1965 wt. ppm)

  20. Cracking in hydride blisters in Zr-2.5Nb pressure tubes

    International Nuclear Information System (INIS)

    When the pressure tubes contact to the calandria tubes in the CANDU reactor, temperature gradient in the Zr-2.5Nb pressure tube causes the thermal diffusion of hydrogen and formation of hydride blisters. This surface shape change is a result of the volume expansion associated with the transformation from pressure tube matrix to δ-phase hydride. Cracking in the hydride blisters may cause a direct failure of pressure tubes or develope to the delayed hydride cracking. The Zr-2.5Nb pressure tube specimen are hydrided by an electrolytic method and homogenized considering the temperature and time of hydrogen diffusion. The hydride blisters are formed on the outer surface of the specimen by a thermal diffusion between a heat bath maintained at the temperature of 415 deg C and an aluminum cold finger cooled with the flowing water of 15 deg C. An optical microscopy and 3-dimensional profilometry were used to characterize the hydride blisters with different hydrogen concentrations and thermal diffusion times. It reveals higher possibility of cracking for higher hydrogen concentration and longer time for thermal diffusion. The mechanism of cracking in the hydride blister is discussed

  1. Hydride trapping for AAS: Complex analytical problems can be handled with a simple instrumentation

    Czech Academy of Sciences Publication Activity Database

    Dědina, Jiří; de Moraes, D. P.; Dessuy, M. B.; Kratzer, Jan; Matoušek, Tomáš; de Moraes Flores, E. M.; Vale, M. G. R.

    Ankara Üniversitesi, 2011. [National Spectroscopy Congress /12./. 18.05.2011-22.05.2011, Antalya] R&D Projects: GA ČR GA203/09/1783 Institutional research plan: CEZ:AV0Z40310501 Keywords : atomic absorption spectrometry * hydride generation * hydride trapping Subject RIV: CB - Analytical Chemistry, Separation

  2. Absorption kinetics and hydride formation in magnesium films: Effect of driving force revisited

    International Nuclear Information System (INIS)

    Electrochemical hydrogen permeation measurements and in situ gas-loading X-ray diffraction measurements were performed on polycrystalline Mg films. Hydrogen diffusion constants, the hydride volume content and the in-plane stress were determined for different values of driving forces at 300 K. For α-Mg–H, a hydrogen diffusion constant of DHMg=7(±2)·10-11 m2 s−1 was determined. For higher concentrations, different kinetic regimes with reduced apparent diffusion constants DHtot were found, depending on the driving force, decreasing to about DHtot = 10−18 m2 s−1. This lowest measured diffusion constant is two orders of magnitude larger than that of bulk β-MgH2, and the difference is ascribed to a contribution from a fast diffusion along grain boundaries. The different kinetics regimes are attributed to the spatial distribution of hydrides. A heterogeneous hydride nucleation and growth model is suggested that is based on hemispherical hydrides spatially distributed according to the nuclei densities expressed as a function of the driving force. The model allows us to qualitatively explain the complex stress development, the different diffusion regimes and the blocking-layer thickness. As the blocking-layer thickness inversely scales with the driving force, small driving forces allow the hydriding of large film volume fractions. Maximum stress situations occur for hydride distances reaching four times the hydride radius and for hydride distances equaling the film thickness

  3. Hydride precipitation crack propagation in zircaloy cladding during a decreasing temperature history

    International Nuclear Information System (INIS)

    An assessment of safety, design, and cost tradeoff issues for short (ten to fifty years) and longer (fifty to hundreds of years) interim dry storage of spent nuclear fuel in Zircaloy rods shall address potential failures of the Zircaloy cladding caused by the precipitation response of zirconium hydride platelets. To perform such assessment analyses rigorously and conservatively will be necessarily complex and difficult. For Zircaloy cladding, a model for zirconium hydride induced crack propagation velocity was developed for a decreasing temperature field and for hydrogen, temperature, and stress dependent diffusive transport of hydrogen to a generic hydride platelet at a crack tip. The development of the quasi-steady model is based on extensions of existing models for hydride precipitation kinetics for an isolated hydride platelet at a crack tip. An instability analysis model of hydride-crack growth was developed using existing concepts in a kinematic equation for crack propagation at a constant thermodynamic crack potential subject to brittle fracture conditions. At the time an instability is initiated, the crack propagation is no longer limited by hydride growth rate kinetics, but is then limited by stress rates. The model for slow hydride-crack growth will be further evaluated using existing available data. (authors)

  4. Experiments on hadronic-atom x-ray intensities of hydrides and deuterides

    Energy Technology Data Exchange (ETDEWEB)

    Wiegand, C.E.; Lum, G.K.; Godfrey, G.L.

    1977-04-01

    Kaonic-atom x-ray intensities of elements Z = 3, 6, 8, 11, and 20 were significantly reduced when the elements were in hydride form. The ratios I (ZH/sub m/)/I (Z) have a noticeable Z dependence. Deuterides of C and O showed slightly less x-ray emission than their hydride counterparts.

  5. Thermal and mechanical properties of zirconium hydrides with various hafnium contents

    International Nuclear Information System (INIS)

    Zirconium (Zr) hydride is currently expected as a neutron shield material for fast reactors. In order to evaluate safety and economic efficiency of the nuclear reactor, the thermal and mechanical properties of the hydride should be understood. In addition, since chemical properties of Zr and hafnium (Hf) are quite similar, Zr contains a few percent Hf generally. Therefore, it is very important to evaluate the effect of Hf content on the properties of Zr hydride. In the present study, fine bulk samples of δ-phase Zr hydrides with various Hf contents were prepared and their thermal and mechanical properties were investigated. We examined the phase states and the microstructure of the hydrides by means of X-ray diffraction and SEM/EDX analyses. In the temperature range from room temperature to 673 K, the heat capacity and the thermal diffusivity of the hydrides were measured and the thermal conductivity was evaluated. The Vickers hardness and the sound velocity of the hydrides were measured at room temperature, and the elastic modulus was calculated from the measured sound velocity. The effects of temperature and Hf content on the properties of Zr hydrides were studied. (author)

  6. Hydride precipitation and its influence on mechanical properties of notched and unnotched Zircaloy-4 plates

    International Nuclear Information System (INIS)

    The hydride formation and its influence on the mechanical performance of hydrided Zircaloy-4 plates containing different hydrogen contents were studied at room temperature. For the unnotched plate samples with the hydrogen contents ranging from 25 to 850 wt. ppm, the hydrides exerted an insignificant effect on the tensile strength, while the ductility was severely degraded with increasing hydrogen content. The fracture mode and degree of embrittlement were strongly related to the hydrogen content. When the hydrogen content reached a level of 850 wt. ppm, the plate exhibited negligible ductility, resulting in almost completely brittle behavior. For the hydrided notched plate, the tensile stress concentration associated with the notch tip facilitated the hydride accumulation at the region near the notch tip and the premature crack propagation through the hydride fracture during hydriding. The final brittle through-thickness failure for this notched sample was mainly attributed to the formation of a continuous hydride network on the thickness section and the obtained very high hydrogen concentration (estimated to be 1965 wt. ppm)

  7. Characterizing optical dipole trap via fluorescence of trapped cesium atoms

    Institute of Scientific and Technical Information of China (English)

    LIU; Tao; GENG; Tao; YAN; Shubin; LI; Gang; ZHANG; Jing; WANG; Junmin; PENG; Kunchi; ZHANG; Tiancai

    2006-01-01

    Optical dipole trap (ODT) is becoming an important tool of manipulating neutral atoms. In this paper ODT is realized with a far-off resonant laser beam strongly focused in the magneto-optical trap (MOT) of cesium atoms. The light shift is measured by simply monitoring the fluorescence of the atoms in the magneto-optical trap and the optical dipole trap simultaneously. The advantages of our experimental scheme are discussed, and the effect of the beam waist and power on the potential of dipole trap as well as heating rate is analyzed.

  8. Cesium fallout in Norway after the Chernobyl accident

    International Nuclear Information System (INIS)

    Results of country-wide measurements of 137Cs and 134 Cs in soil samples in Norway after the Chernobyl accident are reported. The results clearly demonstrates that municipalities in the central part of southern Norway, Troendelag and the southern part of Nordland, have been rather heavily contaminated. The total fallout of 137Cs and 134Cs from the Chernobyl accident in Norway is estimated to 2300 TBq and 1200 TBq, respectively. This is approximately 6% of the cesium activity released from the reactor

  9. Sensitive Detection of Cold Cesium Molecules by Radiative Feshbach Spectroscopy

    OpenAIRE

    Chin, Cheng; Kerman, Andrew J.; Vuletić, Vladan; Chu, Steven

    2002-01-01

    We observe the dynamic formation of $Cs_2$ molecules near Feshbach resonances in a cold sample of atomic cesium using an external probe beam. This method is 300 times more sensitive than previous atomic collision rate methods, and allows us to detect more than 20 weakly-coupled molecular states, with collisional formation cross sections as small as $\\sigma =3\\times 10^{-16}$cm$^2$. We propose a model to describe the atom-molecule coupling, and estimate that more than $2 \\times 10^5$ $Cs_2$ mo...

  10. Specific heat and thermodynamic properties of the cesium perchlorate

    International Nuclear Information System (INIS)

    The cesium perchlorate specific heat has been measured in a vacuum adiabatic microcalorimeter in the 10-365 K range. On the basis of the data obtained the thermodynamic functions are calculated. Csub(p)sup(0) (298.15 K) = 110.4+-0.2 J/Kxmol; S0 (298.15 K)=175.9+-0.5 J/Kxmol; H0 (298.15 K) - H0(0)=22280+-50 J/mol; - [G0 (289.15 K) - H0(0)]/T = 101.2+-0.2 J/Kxmol

  11. Equilibrium and kinetic studies of the sorption of cesium by potassium nickel hexacyanoferrate complex

    International Nuclear Information System (INIS)

    Sorption of cesium from nitric acid medium by potassium nickel hexacyanoferrate, KNiFC, was investigated using the batch technique. The effect of hydrogen ion concentration on the distribution coefficient of cesium has been studied in the pH range 1-5.5. The effect of particle size, the temperature on the sorption equilibrium and rate of uptake of cesium were investigated. The temperature effect on both sorption equilibrium and rate of uptake was found to be limited. The kinetic study shows that the sorption is controlled by particle diffusion mechanism. The diffusivity of cesium ions into different particle sizes of KNiFC, the activation energy, and the entropy change of the sorption process were calculated. The effect of the presence of cobalt ions on the equilibrium and the rate of uptake of cesium is presented. (author)

  12. Rational Design of Cesium-Selective Ionophores and Chemosensors: Dihydrocalix[4]arene Crown-6 Ethers

    Energy Technology Data Exchange (ETDEWEB)

    Sachleben, Richard A.; Bryan, Jeffrey C.; Brown, Gilbert M.; Engle, Nancy L.; Haverlock, Tamara J.; Hay, Benjamin P.; Urvoas, Agathe; Moyer, Bruce A.

    2003-12-15

    Molecular mechanics calculations performed on calix[4]arene crown-6 ethers predict that the 1,3-dihydro derivatives will exhibit greater complementarity for potassium and cesium ions than the parent 1,3-dialkoxy calix crowns. The X-ray crystal structures of 1,3-alt bis-octyloxycalix[4]arene benzocrown-6 ether, dihydrocalix[4]arene benzocrown-6 ether, and the cesium nitrate complex of dihydrocalix[4]arene benzocrown-6 ether were determined. The cesium complex structure corresponds closely to the structure predicted by molecular mechanics. The dihydrocalix[4]arene crown-6 ethers exhibit enhanced cesium selectivity in the extraction of alkali metal salts and provide a platform for a highly sensitive and selective cesium chemosensor.

  13. Investigation of the behavior during incineration of cesium adsorbed in vegetation waste

    International Nuclear Information System (INIS)

    The decontamination of wood and grass contaminated by radioactive cesium released after a nuclear power plant accident is a significant problem. During this research, the behavior of radioactive cesium during incineration was investigated experimentally. Non-radioactive cesium chloride was adsorbed into sunflower and wood pellet samples, and was burned in a lab-scale fluidized bed combustor. Up to 70% of the cesium was transferred to fly ash, which is captured in the quartz filter of the exhaust line. The concentration of cesium in the fly ash is 10 times greater than in the bottom ash, as the amount of fly ash makes up approximately 20% of the entire ash content. Careful management is vital when handling and disposing of fly ash generated from the incineration of vegetation waste. (author)

  14. Mathematical modeling of the nickel/metal hydride battery system

    Energy Technology Data Exchange (ETDEWEB)

    Paxton, B K [Univ. of California, Berkeley, CA (United States). Dept. of Chemical Engineering

    1995-09-01

    A group of compounds referred to as metal hydrides, when used as electrode materials, is a less toxic alternative to the cadmium hydroxide electrode found in nickel/cadmium secondary battery systems. For this and other reasons, the nickel/metal hydride battery system is becoming a popular rechargeable battery for electric vehicle and consumer electronics applications. A model of this battery system is presented. Specifically the metal hydride material, LaNi{sub 5}H{sub 6}, is chosen for investigation due to the wealth of information available in the literature on this compound. The model results are compared to experiments found in the literature. Fundamental analyses as well as engineering optimizations are performed from the results of the battery model. In order to examine diffusion limitations in the nickel oxide electrode, a ``pseudo 2-D model`` is developed. This model allows for the theoretical examination of the effects of a diffusion coefficient that is a function of the state of charge of the active material. It is found using present data from the literature that diffusion in the solid phase is usually not an important limitation in the nickel oxide electrode. This finding is contrary to the conclusions reached by other authors. Although diffusion in the nickel oxide active material is treated rigorously with the pseudo 2-D model, a general methodology is presented for determining the best constant diffusion coefficient to use in a standard one-dimensional battery model. The diffusion coefficients determined by this method are shown to be able to partially capture the behavior that results from a diffusion coefficient that varies with the state of charge of the active material.

  15. Another Look at the Mechanisms of Hydride Transfer Enzymes with Quantum and Classical Transition Path Sampling.

    Science.gov (United States)

    Dzierlenga, Michael W; Antoniou, Dimitri; Schwartz, Steven D

    2015-04-01

    The mechanisms involved in enzymatic hydride transfer have been studied for years, but questions remain due, in part, to the difficulty of probing the effects of protein motion and hydrogen tunneling. In this study, we use transition path sampling (TPS) with normal mode centroid molecular dynamics (CMD) to calculate the barrier to hydride transfer in yeast alcohol dehydrogenase (YADH) and human heart lactate dehydrogenase (LDH). Calculation of the work applied to the hydride allowed for observation of the change in barrier height upon inclusion of quantum dynamics. Similar calculations were performed using deuterium as the transferring particle in order to approximate kinetic isotope effects (KIEs). The change in barrier height in YADH is indicative of a zero-point energy (ZPE) contribution and is evidence that catalysis occurs via a protein compression that mediates a near-barrierless hydride transfer. Calculation of the KIE using the difference in barrier height between the hydride and deuteride agreed well with experimental results. PMID:26262969

  16. Characteristics of hydriding and hydrogen embrittlement of the Ti-Al-Zr alloy

    International Nuclear Information System (INIS)

    The characteristics of hydriding and hydrogen embrittlement of the Ti-Al-Zr alloy were evaluated. The amount of hydrogen absorbed into the alloy at 500 deg. C was continuously monitored using a hydrogen pressure measurement. The rate of decrease in hydrogen pressure indicated a high absorption rate of hydrogen into the alloy, following a linear rate law. X-ray diffraction studies showed the formation of δ-phase titanium hydride (TiH1.97) after hydriding. At room temperature, the alloy showed much sensitivity to embrittlement in ductility by hydrogen. The δ-hydrides in the grain boundaries promoted the crack propagation in the presence of stress, leading to the cleavage failure mode. However, the tensile strengths were almost independent of the hydrogen content up to 1174 ppm. It is thus concluded that the δ-hydride acts to decrease the ductility without affecting tensile strengths

  17. Evaluation of hydride blisters in zirconium pressure tube in CANDU reactor

    International Nuclear Information System (INIS)

    When the garter springs for maintaining the gap between the pressure tube and the calandria tube are displaced in the CANDU reactor, the sagging of pressure tube results in a contact to the calandria tube. This causes a temperature difference between the inner and outer surface of the pressure tube. The hydride can be formed at the cold spot of outer surface and the volume expansion by hydride dormation causes the blistering in the zirconium alloys. An incident of pressure tube rupture due to the hydride blisters had happened in the Canadian CANDU reactor. This report describes the theoretical development and models on the formation and growth of hydride blister and some experimental results. The evaluation methodology and non-destructive testing for hydride blister in operating reactors are also described

  18. Assessing nanoparticle size effects on metal hydride thermodynamics using the Wulff construction.

    Science.gov (United States)

    Kim, Ki Chul; Dai, Bing; Karl Johnson, J; Sholl, David S

    2009-05-20

    The reaction thermodynamics of metal hydrides are crucial to the use of these materials for reversible hydrogen storage. In addition to altering the kinetics of metal hydride reactions, the use of nanoparticles can also change the overall reaction thermodynamics. We use density functional theory to predict the equilibrium crystal shapes of seven metals and their hydrides via the Wulff construction. These calculations allow the impact of nanoparticle size on the thermodynamics of hydrogen release from these metal hydrides to be predicted. Specifically, we study the temperature required for the hydride to generate a H(2) pressure of 1 bar as a function of the radius of the nanoparticle. In most, but not all, cases the hydrogen release temperature increases slightly as the particle size is reduced. PMID:19420649

  19. Assessing nanoparticle size effects on metal hydride thermodynamics using the Wulff construction

    International Nuclear Information System (INIS)

    The reaction thermodynamics of metal hydrides are crucial to the use of these materials for reversible hydrogen storage. In addition to altering the kinetics of metal hydride reactions, the use of nanoparticles can also change the overall reaction thermodynamics. We use density functional theory to predict the equilibrium crystal shapes of seven metals and their hydrides via the Wulff construction. These calculations allow the impact of nanoparticle size on the thermodynamics of hydrogen release from these metal hydrides to be predicted. Specifically, we study the temperature required for the hydride to generate a H2 pressure of 1 bar as a function of the radius of the nanoparticle. In most, but not all, cases the hydrogen release temperature increases slightly as the particle size is reduced.

  20. Strategies for the improvement of the hydrogen storage properties of metal hydride materials.

    Science.gov (United States)

    Wu, Hui

    2008-10-24

    Metal hydrides are an important family of materials that can potentially be used for safe, efficient and reversible on-board hydrogen storage. Light-weight metal hydrides in particular have attracted intense interest due to their high hydrogen density. However, most of these hydrides have rather slow absorption kinetics, relatively high thermal stability, and/or problems with the reversibility of hydrogen absorption/desorption cycling. This paper discusses a number of different approaches for the improvement of the hydrogen storage properties of these materials, with emphasis on recent research on tuning the ionic mobility in mixed hydrides. This concept opens a promising pathway to accelerate hydrogenation kinetics, reduce the activation energy for hydrogen release, and minimize deleterious possible by-products often associated with complex hydride systems. PMID:18821548

  1. Mobility and chemical bond of hydrogen in titanium and palladium hydrides

    International Nuclear Information System (INIS)

    The probabilities for π- meson capture by hydrogen are measured at 25, 155 and 200 deg C in TiHsub(1.65) hydride and at 25, -120 and -196 deg C in PdHsub(0.67) hydride. An analysis of the results obtained shows that within the accuracy of the measurements (approximately 10%) a sharp (up to 1012) change in the mobility of hydrogen in the hydrides induced by temperature changes within the ranges indicated does not noticeably affect the probabilities for π- meson capture by bound hydrogen, i.e. does not lead to appreciable changes in the Me-H bond. A comparison of the capture probabilities for palladium hydride and hydrides of neighboring transition metals shows that there are no pronounced anomalies in the Pd-H bond

  2. Hydride Ions, HCO+ and Ionizing Irradiation in Star Forming Region

    Science.gov (United States)

    Benz, Arnold O.; Bruderer, Simon; van Dishoeck, Ewine

    2016-06-01

    Hydrides are fundamental precursor molecules in cosmic chemistry and many hydride ions have become observable in high quality for the first time thanks to the Herschel Space Observatory. Ionized hydrides, such as CH+ and OH+ and also HCO+ affect the chemistry of molecules such as water. They also provide complementary information on irradiation by far UV (FUV) or X-rays and gas temperature.We explore hydrides of the most abundant heavier elements in an observational survey covering star forming regions with different mass and evolutionary state. Twelve YSOs were observed with HIFI on Herschel in 6 spectral settings providing fully velocity-resolved line profiles. The YSOs include objects of low (Class 0 and I), intermediate, and high mass, with luminosities ranging from 4 Ls to 2 105 Ls.The targeted lines of CH+, OH+, H2O+, and C+ are detected mostly in blue-shifted absorption. H3O+ and SH+ are detected in emission and only toward some high-mass objects. For the low-mass YSOs the column density ratios of CH+/OH+ can be reproduced by simple chemical models implying an FUV flux of 2 – 400 times the ISRF at the location of the molecules. In two high-mass objects, the UV flux is 20 – 200 times the ISRF derived from absorption lines, and 300 – 600 ISRF using emission lines. Upper limits for the X-ray luminosity can be derived from H3O+ observations for some low-mass objects.If the FUV flux required for low-mass objects originates at the central protostar, a substantial FUV luminosity, up to 1.5 Ls, is required. For high-mass regions, the FUV flux required to produce the observed molecular ratios is smaller than the unattenuated flux expected from the central object(s) at the Herschel beam radius. This is consistent with an FUV flux reduced by circumstellar extinction or by bloating of the protostar.The ion molecules are proposed to form in FUV irradiated cavity walls that are shocked by the disk wind. The shock region is turbulent, broadening the lines to some 1

  3. Data acquisition for delayed hydride cracking studies using DCPD technique

    International Nuclear Information System (INIS)

    Direct current potential drop (DCPD) is a commonly used technique for making measurements on crack propagation in Delayed Hydride Cracking (DHC) studies on materials. It consists of passing a highly stable current ( 5-15A) through a Compact Toughness (CT) specimen of the material subjected to a mechanical load at the requisite elevated temperature, and precisely measuring and tracking the very small voltage developed across two points of specific geometry on it. Though simple in principle, this involves measuring and extracting very small signals from inevitable large spurious signals in a harsh environment, and it requires a high quality data acquisition and analysis system to extract the required information from the experiment

  4. Equilibrium composition for the reaction of plutonium hydride with air

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    There are six independent constituents with 4 chemical elements, i.e. PuH2.7(s), PuN(s), Pu2O3(s), N2, O2 and H2, therefore , the system described involves of 2 independent reactions ,both those of the experimental, which indicates that the chemical equilibrium is nearly completely approached. Therefore, it is believed that the reaction rate of plutonium hydride with air is extremely rapid. The present paper has briefly discussed the simultaneous reactions and its thermodynamic coupling effect.

  5. Simulation of metal hydride reactor with aluminium foam matrix

    International Nuclear Information System (INIS)

    'Full text:' A 1-D model has been developed for testing different designs of hydride reactors. The computer program can simulate a complete reactor or a part of it in planar, cylindrical or spherical geometry. It reproduces an experimental loop: absorption followed by desorption and calculates heat transfer during the reaction. Simulation results have been confronted to experimental data with very good correlation. A reactor with a heat transfer matrix inside, such as aluminum foam, can be simulated. We have evaluated the size limits of a reactor and the category of foam that preserves the good reaction kinetic performances of a reactor filled with LaNi5. (author)

  6. Uranium-zirconium hydride TRIGA-LEU fuel

    International Nuclear Information System (INIS)

    The development and testing of TRIGA-LEU fuel with up to 45 wt-% U is described. Topics that are discussed include properties of hydride fuels, the prompt negative temperature coefficient, pulse heating tests, fission product retention, and the limiting design basis parameter and values. General specifications for Er-U-ZrH TRIGA-LEU fuel with 8.5 to 45 wt-% U and an outline of the inspections during manufacture of the fuel are also included. (author). 8 figs, 1 tab

  7. Comparison between different reactions of group IV hydride with H

    Institute of Scientific and Technical Information of China (English)

    ZHANG; Shaolong; ZHANG; Xuqiang; ZHANG; Qinggang; ZHANG; Yici

    2006-01-01

    The four-dimensional time-dependent quantum dynamics calculations for reactions of group IV hydride with H are carried out by employing the semirigid vibrating rotor target model and the time-dependent wave packet method. The reaction possibility, cross section and rate constants for reactions (H+SiH4 and H+GeH4) in different initial vibrational and rotational states are obtained. The common feature for such kind of reaction process is summarized. The theoretical result is consistent with available measurement, which indicates the credibility of this theory and the potential energy surface.

  8. A compact hydrogen recycling system using metal hydrides

    International Nuclear Information System (INIS)

    A gas recycling system to prevent losses of isotopically enriched hydrogen gas has been developed for the operation of a liquid target (2.7 l) used by the Radiative Muon Capture group at TRIUMF. The experimental requirements for high gas purity (chemical impurities below 10-9), low operating pressure (below 1 bar abs) and high loading pressure (about 10 bar needed for a palladium purifier) together with the usual hydrogen safety requirements were satisfied with a metal hydride storage device in combination with a small pump/compressor system. A description of the complete system together with its characteristic operational data are given in this paper. ((orig.))

  9. The calculated rovibronic spectrum of scandium hydride, ScH

    CERN Document Server

    Lodi, Lorenzo; Tennyson\\, Jonathan

    2015-01-01

    The electronic structure of six low-lying electronic states of scandium hydride, $X\\,{}^{1}\\Sigma^+$, $a\\,{}^{3}\\Delta$, $b\\,{}^{3}\\Pi$, $A\\,{}^{1}\\Delta$ $c\\,{}^{3}\\Sigma^+$, and $B\\,{}^{1}\\Pi$, is studied using multi-reference configuration interaction as a function of bond length. Diagonal and off-diagonal dipole moment, spin-orbit coupling and electronic angular momentum curves are also computed. The results are benchmarked against experimental measurements and calculations on atomic scandium. The resulting curves are used to compute a line list of molecular ro-vibronic transitions for $^{45}$ScH.

  10. Photo-association of cold cesium atoms. Formation and characterisation of a cold cloud of diatomic cesium molecules

    International Nuclear Information System (INIS)

    In a photo-association process, two colliding cold cesium atoms absorb one photon to form an ultracold molecule, electronically excited in a well defined ro-vibration level. Because of the small initial kinetic energy of the free atoms, the photo-association is resonant and permits high resolution spectroscopy of long-range states. We report spectra for states correlated to the excited limit 6S+6P. The 1u (6S+6P3/2) state is a pure long-range molecules. It hardly consists in a molecule, but rather in a pair of two atoms linked at 1, 5 nm by the multipolar electrostatic interaction. The intensity modulation of spectral lines for a given vibrational progression reflects the nodal structure of the radial s-wave function of two ground state atoms. The photo-association of the state 0g-(6S +6P3/2) of polarized atoms permits determining the scattering length of the triplet state of cesium (aT = -530 a0) and the Van der Waals parameter of the molecular ground state (C6 = 6510 u.a.). Photo-association of cold cesium atoms also leads to the formation of translationally cold molecules in singlet and triplet fundamental states after spontaneous emission of the excited molecules. Various schemes are characterized. The particular double-well shape of 0g-(6S+6P3/2) and 1u(6S+6P3/2) states creates a Condon point at intermediate distance. These states constitute ideal cases for very efficient formation of cold molecules. The cold molecular cloud is analyzed: temperatures as low as 20 micro-Kelvin are measured and the distribution of the ro-vibrational levels is studied. The efficiencies of the photo-association process and of the formation of cold molecules are measured, and compared with theoretical calculations. (author)

  11. Precipitation of reoriented hydrides and textural change of α-zirconium grains during delayed hydride cracking of Zr-2.5%Nb pressure tube

    International Nuclear Information System (INIS)

    Cantilever beam (CB) specimens referred to as L90 and L60 with the notch directions tilted normal to, and at an angle of 60 deg. to, the transverse direction of a cold-worked and annealed Zr-2.5%Nb pressure tube, respectively, were subjected to delayed hydride cracking (DHC) testing at 250 deg. C. L60 specimen showed slanted growth of the DHC crack compared to L90 without tilting. An X-ray diffractometric study was carried out on the fractured surfaces of the two CB specimens after DHC testing. The δ-hydride phase was confirmed to sit on the fracture surface, demonstrating the growth of the DHC crack through fracturing of the reoriented hydrides. Furthermore, the texture of the reoriented hydrides was determined for the first time. Comparing the pole figures of the {1 1 1}δ-hydride and the (0 0 0 1)α-zirconium, it is concluded that the reoriented hydrides nucleate first of all at the α-zirconium grains. A change in the orientation of the α-zirconium grains, mainly by twinning on the {1 0 1-bar} planes, was demonstrated to occur during the propagation of the DHC crack. On the basis of the above findings, a mechanism of the DHC was discussed

  12. Formation of alloys in Ti-V system in hydride cycle and synthesis of their hydrides in self-propagating high-temperature synthesis regime

    Energy Technology Data Exchange (ETDEWEB)

    Aleksanyan, A.G., E-mail: a.g.aleks_yan@mail.ru [A.B. Nalbandyan Institute of Chemical Physics of Armenian NAS, 5/2 P.Sevak Str., Yerevan 0014 (Armenia); Dolukhanyan, S.K. [A.B. Nalbandyan Institute of Chemical Physics of Armenian NAS, 5/2 P.Sevak Str., Yerevan 0014 (Armenia); Shekhtman, V.Sh. [Institute of Solid State Physics, RAS, Chernogolovka, Moscow District 142432 (Russian Federation); Huot, J., E-mail: jacques_huot@uqtr.ca [Institut de recherche sur l' hydrogene, Universite du Quebec a Trois-Rivieres (Canada); Ter-Galstyan, O.P.; Mnatsakanyan, N.L. [A.B. Nalbandyan Institute of Chemical Physics of Armenian NAS, 5/2 P.Sevak Str., Yerevan 0014 (Armenia)

    2011-09-15

    Research highlights: > We synthesize Ti-V alloys by new 'hydride cycle' method. Structural characteristics of formed alloys we investigate by X-ray diffraction. > We show that the alloys contain mainly BCC crystal structure. > We investigate the interaction of the synthesized alloys with hydrogen in combustion regime. > We study the properties of hydrides by X-ray, DTA and DSC analyses. - Abstract: In the present work, the possibility of formation of titanium and vanadium based alloys of BCC structure using hydride cycle was investigated. The mechanism of formation of alloys in Ti-V system from the powders of hydrides TiH{sub 2} and VH{sub 0.9} (or of V) by compaction followed by dehydrogenation was studied. Then, the interaction of the synthesized alloys with hydrogen in combustion regime (self-propagating high-temperature synthesis, SHS) resulting in hydrides of these alloys was investigated. DTA and DSC analyses of some alloys and their hydrides were performed and their thermal characteristics were measured.

  13. Transportable cesium irradiator (TPCI): Final safety analysis report: Revision 1

    International Nuclear Information System (INIS)

    This Final Safety Analysis Report describes the Transportable Cesium Irradiator (TPCI) and assesses the hazards associated with its operation. The TPCI consists of a mobile, lead-shielded, irradiation unit with support equipment mounted within an enclosed trailer. The irradiation unit has two basic compartments; a source chamber sized to mate with the transportation cask which houses the source capsules, and an irradiation chamber formed as a large shielded cylinder (drum) with a window. The irradiation chamber is mounted on a large diameter support bearing. As this chamber is rotated its window moves from the product access door, where produce is inserted or extracted, to a position in line with a similar window in the source chamber. When the windows are aligned the produce is irradiated, while the back wall of the irradiation chamber shields the product access door. The TPCI is designed to be transported throughout the continental United States. The transportation cask containing the cesium source capsules is transported separately from the irradiation unit and is installed when the TPCI unit has been readied for operation at a particular site. The transportation cask is a separate unit and is documented in a separate FSAR

  14. Morphological and electrical properties of zirconium vanadate doped with cesium

    Directory of Open Access Journals (Sweden)

    Marwa F. Elkady

    2014-09-01

    Full Text Available Cesium doped zirconium vanadate ZrV2O7 with different Cs dopant content (Cs/Zr varied from 0 to 0.5 in weight ratio were fabricated by hydrothermal technique at 120 °C for 60 min. The synthesized materials are thermally treated using microwave technique. The structural and morphological properties of the synthesized materials and thermally treated samples were investigated using XRD and SEM respectively. It was evident that all synthesized specimens have cubic phase structural without any extra phase but after heat treatment Orthorhombic phase appear with doped samples. However, the morphological structure of the doped synthesized materials has transferred from nanoparticles into rods aspect with heat treatment for the different dopant ratio. Moreover, the electrical properties of both the synthesized and thermally treated materials are studied by AC impedance measurements. The results indicated that the ionic conductivity of Cs-doped ZrV2O7 materials decreased by increasing the dopant ratio while that thermally treated samples the ionic conductivity increase by increasing the dopant ratio. Finally, the concentration of cesium dopants is found to play crucial role in tuning the morphology and electrical properties of nanostructures.

  15. A study of strontium and cesium sorption on granite

    International Nuclear Information System (INIS)

    The diffusion and sorption of cesium and strontium in crushed granite particles is discussed. Sorption experiments have been performed with one granite from Finnsjoen outside Forsmark on the east coast of Sweden and one granite from the Stripa mine in central Sweden. Granite samples have been crushed and screened, and six different particle size fractions from 0.10-0.12 mm to 4-5 mm of each rock have been used in the experiments. The initial concentrations of inactive cesium and strontium were 10-15 ppm. The experimental data indicate that the amount of sorption is dependent not only on the mass of granite particles, but also to some extent on the size of the particles. An attempt has been made to distinguish between sorption on external surfaces and inner surfaces. The amount of external surface adsorption was found to vary from 15-40 % of the total adsorption capacity for the particle size fraction 0.10-0.12 mm to a few percent or less for the largest particles used. (Auth.)

  16. Kelvin probe studies of cesium telluride photocathode for AWA photoinjector

    International Nuclear Information System (INIS)

    Cesium telluride is an important photocathode as an electron source for particle accelerators. It has a relatively high quantum efficiency (>1%), is sufficiently robust in a photoinjector, and has a long lifetime. This photocathode is grown in-house for a new Argonne Wakefield Accelerator (AWA) beamline to produce high charge per bunch (≈50nC) in a long bunch train. Here, we present a study of the work function of cesium telluride photocathode using the Kelvin probe technique. The study includes an investigation of the correlation between the quantum efficiency and the work function, the effect of photocathode aging, the effect of UV exposure on the work function, and the evolution of the work function during and after photocathode rejuvenation via heating. -- Highlights: ► The correlation between Quantum Efficiency (QE) and work function. ► How QE and work function evolve together. ► Rejuvenation of the photocathode via heating and the effect on work function. ► The effects on the work function due to exposure to UV light

  17. Radiation doses resulting from incorporated radioactive cesium isotopes

    International Nuclear Information System (INIS)

    Age-dependent dose factors are given for inhaled or ingested cesium isotopes, which have been calculated on the basis of published data on the biokinetics of cesium in the human organism. Tabulated data are presented for Cs-129, Cs-130, Cs-131, Cs-132, Cs-134, Cs-135, Cs-136, Cs-137(+Ba-137m), and Cs-138. Comparison of results obtained for adults with relevant data published by the ICRP (1978), the NCRP (1977), and Schwarz (1982) shows very good agreement. More significant deviations are however found when comparing the results with data given in the Federal German Radiation Protection Ordinance, both with regard to adults and to infants, particularly refering to the lung data and to those for the gastro-intestinal tract and the skeleton. These discrepancies are primarily due to improved models developed since the time the Radiation Protection Ordinance has been issued, (respiratory and gastro-intestinal tracts), and to improvements achieved with the dosimetric concepts (calculation of dose for bone surfaces instead of the whole skeleton). The dose factors for newborn given by the publication in hand are significantly lower than those given in the Ordinance (for infants); this is a result of age-dependent retention functions having been considered for this publication. The reliability of the dose factor calculations for various ages, pregnant women and fetuses is discussed and quantified. (orig./HP)

  18. Kelvin probe studies of cesium telluride photocathode for AWA photoinjector

    Energy Technology Data Exchange (ETDEWEB)

    Wisniewski, Eric E., E-mail: ewisniew@anl.gov [High Energy Physics Division, Argonne National Laboratory, 9700 S. Cass, Lemont, IL 60439 (United States); Physics Department, Illinois Institute of Technology, 3300 South Federal Street, Chicago, IL 60616 (United States); Velazquez, Daniel [High Energy Physics Division, Argonne National Laboratory, 9700 S. Cass, Lemont, IL 60439 (United States); Physics Department, Illinois Institute of Technology, 3300 South Federal Street, Chicago, IL 60616 (United States); Yusof, Zikri, E-mail: zyusof@hawk.iit.edu [High Energy Physics Division, Argonne National Laboratory, 9700 S. Cass, Lemont, IL 60439 (United States); Physics Department, Illinois Institute of Technology, 3300 South Federal Street, Chicago, IL 60616 (United States); Spentzouris, Linda; Terry, Jeff [Physics Department, Illinois Institute of Technology, 3300 South Federal Street, Chicago, IL 60616 (United States); Sarkar, Tapash J. [Rice University, 6100 Main, Houston, TX 77005 (United States); Harkay, Katherine [Accelerator Science Division, Argonne National Laboratory, 9700 S. Cass, Lemont, IL 60439 (United States)

    2013-05-21

    Cesium telluride is an important photocathode as an electron source for particle accelerators. It has a relatively high quantum efficiency (>1%), is sufficiently robust in a photoinjector, and has a long lifetime. This photocathode is grown in-house for a new Argonne Wakefield Accelerator (AWA) beamline to produce high charge per bunch (≈50nC) in a long bunch train. Here, we present a study of the work function of cesium telluride photocathode using the Kelvin probe technique. The study includes an investigation of the correlation between the quantum efficiency and the work function, the effect of photocathode aging, the effect of UV exposure on the work function, and the evolution of the work function during and after photocathode rejuvenation via heating. -- Highlights: ► The correlation between Quantum Efficiency (QE) and work function. ► How QE and work function evolve together. ► Rejuvenation of the photocathode via heating and the effect on work function. ► The effects on the work function due to exposure to UV light.

  19. Studies on cesium sorption in hydrous zirconium and titanium oxides

    International Nuclear Information System (INIS)

    Significant quantities of 137Cs (T1/2 = 30.1 y) and 90Sr (T1/2 = 28.5 y) are produced as fission products in nuclear reactors. These long-lived gamma-emitting radionuclides, regarded as a waste few decades ago, are being termed now as valuables owing to the upsurge in the utilization of these radioisotopes in the area of medicine, food irradiation, and sewage treatment technologies in recent years. For long-term waste management it is necessary to minimize the volume and toxicity of the waste. Selective recovery and utilization of these radionuclides from the waste is the concept of growing interest to many researchers. Inorganic sorbents are proven candidates for the separation and recovery of cesium and strontium from aqueous waste streams. They are chemically durable and stable against ionizing radiation. In addition, these materials can be converted into unleachable ceramic form for final disposal. Hydrous metal oxides belong to a particular class of inorganic ion exchangers extensively investigated for various applications in nuclear waste treatment. The present study deals with the preparation of hydrous zirconium and titanium oxide and the studies aimed at separation of cesium from aqueous wastes

  20. Spectrally selective optical pumping in Doppler-broadened cesium atoms

    Institute of Scientific and Technical Information of China (English)

    Zhang Jun-Hai; Zeng Xian-Jin; Li Qing-Meng; Huang Qiang; Sun Wei-Min

    2013-01-01

    The D1 line spectrally selective pumping process in Doppler-broadened cesium is analyzed by solving the optical Bloch equations.The process,described by a three-level model with the A scheme,shows that the saturation intensity of broadened atoms is three orders of magnitude larger than that of resting atoms.The |Fg =3> → |Fe-4> resonance pumping can result in the ground state |Fg =4,mF =4> sublevel having a maximum population of 0.157 and the population difference would be about 0.01 in two adjacent magnetic sublevels of the hyperfine (HF) state Fg =4.To enhance the anisotropy in the ground state,we suggest employing dichromatic optical HF pumping by adding a laser to excite D1 line |Fg =4> → |Fe =3>transition,in which the cesium magnetometer sensitivity increases by half a magnitude and is unaffected by the nonlinear Zeeman effect even in Earth's average magnetic field.

  1. Diffusion of strontium, technetium, iodine and cesium in granitic rock

    International Nuclear Information System (INIS)

    The migration of strontium, technetium, iodine and cesium in granitic rock has been studied. Rock samples were taken from drilling cores in granitic and granodioritic rock, and small (2x2x2 cm) rock tablets from the drilling cores were exposed to a groundwater solution containing one of the studied elements at trace levels. The concentration of the element versus penetration depth in the rock tablet was measured radiometrically. The sorption on the mineral faces and the diffusion into the rock were studied by an autoradiographic technique. The cationic strontium and cesium have apparent diffusivities of 10-13 - 10-14 m2/s. The migration is confined to microfissures or filled fractures containing e.g., calcite, epidote or chlorite or in veins with high capacity minerals (e.g. biotite). The anionic iodine and technetium have apparent diffusivities of about 10-14 m2/s. These species migrate along mineral boundaries and in open fractures and to a minor extent in high capacity mineral veins. (orig.)

  2. Mobility of radioactive cesium in soil originated from the Fukushima Daiichi nuclear disaster. Application of extraction experiments

    International Nuclear Information System (INIS)

    Extraction experiments on soil radioactively contaminated by the Fukushima Daiichi Nuclear Power Plant accident were conducted by using a variety of extractants to acquire knowledge on the mobility of radioactive cesium in soil. The experimental results revealed that cesium is tightly bound with soil particles and that radioactive cesium newly deposited on soil due to the accident had apparently a higher mobility than stable cesium commonly existing in soil. The results suggested that radioactive cesium deposited on soil hardly migrates via aqueous processes, although chemical and mineralogical conditions of soil affect their mobility. (author)

  3. Thermoemission and adsorption properties of diborides of transition metals of IV-V groups in cesium vapours

    International Nuclear Information System (INIS)

    Emission and adsorption properties of titanium, zirconium, hafnium, vanadium diborides were studied in vacuum and cesium vapours. Some regularities were established in changes of thermoemission properties in transition from one boride to another. Under pressures p0K interaction of these diborides with cesium plasma is of adsorption character. Evaluation of absorption properties for the diborides in cesium vapours showed for oprimal surface coating with cesium the adsorption energy for cesium ions is qsub(a)=(1.1/1.3) eV and work function is phi sub(min)=(1.25/1.45) eV

  4. A quantitative phase field model for hydride precipitation in zirconium alloys: Part I. Development of quantitative free energy functional

    International Nuclear Information System (INIS)

    A temperature dependent, quantitative free energy functional was developed for the modeling of hydride precipitation in zirconium alloys within a phase field scheme. The model takes into account crystallographic variants of hydrides, interfacial energy between hydride and matrix, interfacial energy between hydrides, elastoplastic hydride precipitation and interaction with externally applied stress. The model is fully quantitative in real time and real length scale, and simulation results were compared with limited experimental data available in the literature with a reasonable agreement. The work calls for experimental and/or theoretical investigations of some of the key material properties that are not yet available in the literature

  5. Development of a component design tool for metal hydride heat pumps

    Science.gov (United States)

    Waters, Essene L.

    Given current demands for more efficient and environmentally friendly energy sources, hydrogen based energy systems are an increasingly popular field of interest. Within the field, metal hydrides have become a prominent focus of research due to their large hydrogen storage capacity and relative system simplicity and safety. Metal hydride heat pumps constitute one such application, in which heat and hydrogen are transferred to and from metal hydrides. While a significant amount of work has been done to study such systems, the scope of materials selection has been quite limited. Typical studies compare only a few metal hydride materials and provide limited justification for the choice of those few. In this work, a metal hydride component design tool has been developed to enable the targeted down-selection of an extensive database of metal hydrides to identify the most promising materials for use in metal hydride thermal systems. The material database contains over 300 metal hydrides with various physical and thermodynamic properties included for each material. Sub-models for equilibrium pressure, thermophysical data, and default properties are used to predict the behavior of each material within the given system. For a given thermal system, this tool can be used to identify optimal materials out of over 100,000 possible hydride combinations. The selection tool described herein has been applied to a stationary combined heat and power system containing a high-temperature proton exchange membrane (PEM) fuel cell, a hot water tank, and two metal hydride beds used as a heat pump. A variety of factors can be used to select materials including efficiency, maximum and minimum system pressures, pressure difference, coefficient of performance (COP), and COP sensitivity. The targeted down-selection of metal hydrides for this system focuses on the system's COP for each potential pair. The values of COP and COP sensitivity have been used to identify pairs of highest interest for

  6. Kinetic deuterium isotope effects on ligand migrations in metal hydrides

    International Nuclear Information System (INIS)

    Variable-temperature (VT) 1H and 13C NMR studies of the complexes (μ-X)2Os3(CO)9(μ3-η2-(CH3CH2)2C2) (X = H or D) reveal that alkyne migration over the face of the cluster is directly linked to hydride migrations on the metal core as evidenced by a temperature-independent isotope effect (kHH/kDD = 1.7). In a related study of the VT 13C NMR of (μ-X)2M3(CO)9(μ3-S) (X = H or D; M = Ru, Os) the observation of a kHH/kDD = 1.6 for both the osmium and ruthenium complexes demonstrates that the first stage of carbonyl averaging is brought about by hydride migration and not axial-radial exchange of carbonyl groups, a process that occurs only at higher temperatures. The mechanistic implications of these results are discussed in the context of the reactivity of metal clusters and the dynamic properties of the metal-hydrogen bond

  7. Lab-size rechargeable metal hydride-air cells

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Wei-Kang; Noreus, Dag [Department of Materials and Enviromental Chemistry, Arrhenius Laboratory, Stockholm University, S-106 91 Stockholm (Sweden)

    2010-09-01

    Lab-size rechargeable metal hydride-air (MH-air) cells with a gas management device were designed in order to minimize the loss of electrolyte. An AB{sub 5}-type hydrogen storage alloy was used as anode materials of the MH-air. The thickness of the metal hydride electrodes was in the range of 3.0-3.4 mm. Porous carbon-based air electrodes with Ag{sub 2}O catalysts were used as bi-functional electrodes for oxygen reduction and generation. The electrodes were first examined in half-cells to evaluate their performance and then assembled into one MH-air cell. The results showed the good cycling stability of the rechargeable MH-air cell with a capacity of 1990 mAh. The discharge voltage was 0.69 V at 0.05-0.1 C. The charge efficiency was about 90%. The specific and volumetric energy densities were about 95Wh kg{sup -1} and 140 Wh L{sup -1}, respectively. (author)

  8. Separation of covalent hydrides by gas-solid chromatography

    International Nuclear Information System (INIS)

    A fully automated method was developed for separating the hydrides of elements of the IVth to VIIIth main subgroup of the periodic system and of Kr and Xe on the basis of their volatility using gas chromatography. The automated instrument allowing to carry out reduction, separation of the gaseous phase, the loading of a PORAPAK-packed column, the chromatographic separation and sampling was controlled by a HP 2116B computer. The elution time, peak area and the number of theoretical column plates were computed from chromatograms. The capture probably proceeded by a type of nonpolar nonspecific sorption (ΔH/Tsub(b) = 19.2 cal/mol.deg). The height of the theoretical plate was 0.05 to 0.1 cm. The technique may be used as a routine radiochemical method for group separations and for the separation of radioactive hydrides contained in the solution of targets irradiated with neutrons or charged particles in the preparation of radioactive sources of short-lived radionuclides, or in destructive activation analysis. (M.K.)

  9. Gas phase contributions to topochemical hydride reduction reactions

    Energy Technology Data Exchange (ETDEWEB)

    Kobayashi, Yoji [Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510 (Japan); CREST, Japan Science and Technology Agency (JST), Kawaguchi, Saitama 332-0012 (Japan); Li, Zhaofei [Institute for Integrated Cell-Material Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8502 (Japan); Hirai, Kei [Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); Tassel, Cédric [Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510 (Japan); The Hakubi Center for Advanced Research, Kyoto University, Yoshida-Ushinomiya-cho, Sakyo-ku, Kyoto 606-8302 (Japan); Loyer, François [Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510 (Japan); Institut des Sciences Chimiques de Rennes, UMR 6226 Université de Rennes 1-CNRS, équipe CSM, Bât. 10B, Campus de Beaulieu, 263, Avenue du Général Leclerc, 35042 Rennes Cedex (France); Ichikawa, Noriya [CREST, Japan Science and Technology Agency (JST), Kawaguchi, Saitama 332-0012 (Japan); Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); Abe, Naoyuki [Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510 (Japan); Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502 (Japan); Yamamoto, Takafumi [Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510 (Japan); Shimakawa, Yuichi [CREST, Japan Science and Technology Agency (JST), Kawaguchi, Saitama 332-0012 (Japan); Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); and others

    2013-11-15

    Alkali and alkali earth hydrides have been used as solid state reductants recently to yield many interesting new oxygen-deficient transition metal oxides. These reactions have tacitly been assumed to be a solid phase reaction between the reductant and parent oxide. We have conducted a number of experiments with physical separation between the reductant and oxides, and find that in some cases reduction proceeds even when the reagents are physically separated, implying reactions with in-situ generated H{sub 2} and, to a lesser extent, getter mechanisms. Our findings change our understanding of these topochemical reactions, and should enhance the synthesis of additional new oxides and nanostructures. - Graphical abstract: Topochemical reductions with hydrides: Solid state or gas phase reaction? Display Omitted - Highlights: • SrFeO{sub 2} and LaNiO{sub 2} were prepared by topochemical reduction of oxides. • Separating the reducing agent (CaH{sub 2}, Mg metal) from the oxide still results in reduction. • Such topochemical reactions can occur in the gas phase.

  10. Electronic Principles of Hydrogen Incorporation and Dynamics in Metal Hydrides

    Directory of Open Access Journals (Sweden)

    Ljiljana Matović

    2012-08-01

    Full Text Available An approach to various metal hydrides based on electronic principles is presented. The effective medium theory (EMT is used to illustrate fundamental aspects of metal-hydrogen interaction and clarify the most important processes taking place during the interaction. The elaboration is extended using the numerous existing results of experiment and calculations, as well as using some new material. In particular, the absorption/desorption of H in the Mg/MgH2 system is analyzed in detail, and all relevant initial structures and processes explained. Reasons for the high stability and slow sorption in this system are noted, and possible solutions proposed. The role of the transition-metal impurities in MgH2 is briefly discussed, and some interesting phenomena, observed in complex intermetallic compounds, are mentioned. The principle mechanism governing the Li-amide/imide transformation is also discussed. Latterly, some perspectives for the metal-hydrides investigation from the electronic point of view are elucidated.

  11. Gas desorption properties of ammonia borane and metal hydride composites

    International Nuclear Information System (INIS)

    'Full text': Ammonia borane (NH3BH3) has been of great interest owing to its ideal combination of low molecular weight and high H2 storage capacity of 19.6 mass %, which exceeds the current capacity of gasoline. DOE's year 2015 targets involve gravimetric as well as volumetric energy densities. In this work, we have investigated thermal decomposition of ammonia borane and calcium hydride composites at different molar ratio. The samples were prepared by planetary ball milling under hydrogen gas atmosphere pressure of 1Mpa at room temperature for 2, and 10 hours. The gas desorption properties were examined by thermal desorption mass spectroscopy (TDMS). The identification of phases was carried out by X-ray diffraction. The results obtain were shown in fig (a),(b),and (c). Hydrogen desorption properties were observed at all molar ratios, but the desorption temperature is significantly lower at around 70 oC at molar ratio 1:1 as shown in fig (c), and unwanted gas (ammonia) emissions were remarkably suppressed by mixing with the calcium hydride. (author)

  12. Electronic structure of the palladium hydride studied by compton scattering

    CERN Document Server

    Mizusaki, S; Yamaguchi, M; Hiraoka, N; Itou, M; Sakurai, Y

    2003-01-01

    The hydrogen-induced changes in the electronic structure of Pd have been investigated by Compton scattering experiments associated with theoretical calculations. Compton profiles (CPs) of single crystal of Pd and beta phase hydride PdH sub x (x=0.62-0.74) have been measured along the [100], [110] and [111] directions with a momentum resolution of 0.14-0.17 atomic units using 115 keV x-rays. The theoretical Compton profiles have been calculated from the wavefunctions obtained utilizing the full potential linearized augmented plane wave method within the local density approximation for Pd and stoichiometric PdH. The experimental and the theoretical results agreed well with respect to the difference in the CPs between PdH sub x and Pd, and the anisotropy in the CPs of Pd or PdH sub x. This study provides lines of evidence that upon hydride formation the lowest valance band of Pd is largely modified due to hybridization with H 1s-orbitals and the Fermi energy is raised into the sp-band. (author)

  13. Gallium Nitride Nanowires Grown by Hydride Vapor Phase Epitaxy

    Institute of Scientific and Technical Information of China (English)

    LIU Zhan-Hui; XIU Xiang-Qan; YAN Huai-Yue; ZHANG Rong; XIE Zi-Li; HAN Ping; SHI Yi; ZHENG You-Dou

    2011-01-01

    @@ GaN nanowires are grown by hydride vapor phase epitaxy using nickel as a catalyst.The properties of the obtained GaN nanowires are characterized by scanning and transmission electron microscopy,electron diffraction,roomtemperature photoluminescence and energy dispersive spectroscopy.The results show that the nanowires are wurtzite single crystals growing along the[0001]direction and a redshift in the photoluminescence is observed due to a superposition of several effects.The Raman spectra are close to those of the bulk GaN and the significantly broadening of those modes indicates the phonon confinement effects associated with the nanoscale dimensions of the system.%GaN nanowires are grown by hydride vapor phase epitaxy using nickel as a catalyst. The properties of the obtained GaN nanowires are characterized by scanning and transmission electron microscopy, electron diffraction, room-temperature photoluminescence and energy dispersive spectroscopy. The results show that the nanowires are wurtzite single crystals growing along the [0001] direction and a redshift in the photoluminescence is observed due to a superposition of several effects. The Raman spectra are close to those of the bulk GaN and the significantly broadening of those modes indicates the phonon confinement effects associated with the nanoscale dimensions of the system.

  14. Interstellar chemistry of nitrogen hydrides in dark clouds

    CERN Document Server

    Gal, Romane Le; Faure, Alexandre; Forêts, Guillaume Pineau des; Rist, Claire; Maret, Sébastien

    2013-01-01

    The aim of the present work is to perform a comprehensive analysis of the interstellar chemistry of nitrogen, focussing on the gas-phase formation of the smallest polyatomic species and in particular nitrogen hydrides. We present a new chemical network in which the kinetic rates of critical reactions have been updated based on recent experimental and theoretical studies, including nuclear spin branching ratios. Our network thus treats the different spin symmetries of the nitrogen hydrides self-consistently together with the ortho and para forms of molecular hydrogen. This new network is used to model the time evolution of the chemical abundances in dark cloud conditions. The steady-state results are analysed, with special emphasis on the influence of the overall amounts of carbon, oxygen, and sulphur. Our calculations are also compared with Herschel/HIFI observations of NH, NH$_2$, and NH$_3$ detected towards the external envelope of the protostar IRAS 16293-2422. The observed abundances and abundance ratios ...

  15. A low tritium hydride bed inventory estimation technique

    International Nuclear Information System (INIS)

    Low tritium hydride beds were developed and deployed into tritium service in Savannah River Site. Process beds to be used for low concentration tritium gas were not fitted with instrumentation to perform the steady-state, flowing gas calorimetric inventory measurement method. Low tritium beds contain less than the detection limit of the IBA (In-Bed Accountability) technique used for tritium inventory. This paper describes two techniques for estimating tritium content and uncertainty for low tritium content beds to be used in the facility's physical inventory (PI). PI are performed periodically to assess the quantity of nuclear material used in a facility. The first approach (Mid-point approximation method - MPA) assumes the bed is half-full and uses a gas composition measurement to estimate the tritium inventory and uncertainty. The second approach utilizes the bed's hydride material pressure-composition-temperature (PCT) properties and a gas composition measurement to reduce the uncertainty in the calculated bed inventory

  16. Superconductive "sodalite"-like clathrate calcium hydride at high pressures

    CERN Document Server

    Wang, Hui; Tanaka, Kaori; Iitaka, Toshiaki; Ma, Yanming

    2012-01-01

    Hydrogen-rich compounds hold promise as high-temperature superconductors under high pressures. Recent theoretical hydride structures on achieving high-pressure superconductivity are composed mainly of H2 fragments. Through a systematic investigation of Ca hydrides with different hydrogen contents using particle-swam optimization structural search, we show that in the stoichiometry CaH6 a body-centred cubic structure with hydrogen that forms unusual "sodalite" cages containing enclathrated Ca stabilizes above pressure 150 GPa. The stability of this structure is derived from the acceptance by two H2 of electrons donated by Ca forming a "H4" unit as the building block in the construction of the 3-dimensional sodalite cage. This unique structure has a partial occupation of the degenerated orbitals at the zone centre. The resultant dynamic Jahn-Teller effect helps to enhance electron-phonon coupling and leads to superconductivity of CaH6. A superconducting critical temperature (Tc) of 220-235 K at 150 GPa obtained...

  17. Electron and nuclear magnetic resonances in compounds and metallic hydrides

    International Nuclear Information System (INIS)

    Proton pulsed Nuclear Magnetic Resonance measurements were performed on the metallic hydrides ZrCr2Hx (x = 2, 3, 4) and ZrV2Hy (y = 2, 3, 4, 5) as a function of temperature between 180 and 400K. The ultimate aim was the investigation of the relaxation mechanisms in these systems by means of the measurement of both the proton (1H) spin-lattice (T1) and spin-spin (T2) relaxation times and to use these data to obtain information about the diffusive motion of the hydrogen atoms. The diffusional activation energies, the jump frequencies and the Korringa constant, Ck, related with the conduction electron contribution to the 1H relaxation were determined for the above hydrides as a function of hydrogen concentration. Our results were analysed in terms of the relaxation models described by Bloembergen, Purcell and Pound (BPP model) and by Torrey. The Korringa type relaxation due to the conduction electrons in metallic systems was also used to interpret the experimental results. We also present the Electron Paramagnetic Ressonance (EPR) study of Gd3+, Nd3+ and Er3+ ions as impurities in several AB3 intermetallic compounds where A = LA, Ce, Y, Sc, Th, Zr and B = Rh, Ir, Pt. The results were analysed in terms of the multiband model previously suggested to explain the behaviour of the resonance parameter in AB2 Laves Phase compounds. (author)

  18. Multi-scale characterization of nanostructured sodium aluminum hydride

    Science.gov (United States)

    NaraseGowda, Shathabish

    Complex metal hydrides are the most promising candidate materials for onboard hydrogen storage. The practicality of this class of materials is counter-poised on three critical attributes: reversible hydrogen storage capacity, high hydrogen uptake/release kinetics, and favorable hydrogen uptake/release thermodynamics. While a majority of modern metallic hydrides that are being considered are those that meet the criteria of high theoretical storage capacity, the challenges lie in addressing poor kinetics, thermodynamics, and reversibility. One emerging strategy to resolve these issues is via nanostructuring or nano-confinement of complex hydrides. By down-sizing and scaffolding them to retain their nano-dimensions, these materials are expected to improve in performance and reversibility. This area of research has garnered immense interest lately and there is active research being pursued to address various aspects of nanostructured complex hydrides. The research effort documented here is focused on a detailed investigation of the effects of nano-confinement on aspects such as the long range atomic hydrogen diffusivities, localized hydrogen dynamics, microstructure, and dehydrogenation mechanism of sodium alanate. A wide variety of microporous and mesoporous materials (metal organic frameworks, porous silica and alumina) were investigated as scaffolds and the synthesis routes to achieve maximum pore-loading are discussed. Wet solution infiltration technique was adopted using tetrahydrofuran as the medium and the precursor concentrations were found to have a major role in achieving maximum pore loading. These concentrations were optimized for each scaffold with varying pore sizes and confinement was quantitatively characterized by measuring the loss in specific surface area. This work is also aimed at utilizing neutron and synchrotron x-ray characterization techniques to study and correlate multi-scale material properties and phenomena. Some of the most advanced

  19. Fast concentration of dissolved forms of cesium radioisotopes from large seawater samples

    International Nuclear Information System (INIS)

    The method developed for cesium concentration from large freshwater samples was tested and adapted for analysis of cesium radionuclides in seawater. Concentration of dissolved forms of cesium in large seawater samples (about 100 L) was performed using composite absorbers AMP-PAN and KNiFC-PAN with ammonium molybdophosphate and potassium–nickel hexacyanoferrate(II) as active components, respectively, and polyacrylonitrile as a binding polymer. A specially designed chromatography column with bed volume (BV) 25 mL allowed fast flow rates of seawater (up to 1,200 BV h-1). The recovery yields were determined by ICP-MS analysis of stable cesium added to seawater sample. Both absorbers proved usability for cesium concentration from large seawater samples. KNiFC-PAN material was slightly more effective in cesium concentration from acidified seawater (recovery yield around 93 % for 700 BV h-1). This material showed similar efficiency in cesium concentration also from natural seawater. The activity concentrations of 137Cs determined in seawater from the central Pacific Ocean were 1.5 ± 0.1 and 1.4 ± 0.1 Bq m-3 for an offshore (January 2012) and a coastal (February 2012) locality, respectively, 134Cs activities were below detection limit (-3). (author)

  20. Development of cesium trapper and single-gas-bubble injector into sodium pool

    International Nuclear Information System (INIS)

    On the core disruptive accident in the sodium cooled fast breeder reactor, in fuel pins the cesium fission product with a high hazard is transferred to the sodium coolant together with noble gas including fission product, and the cesium accumulates on the cover gas area because of its low migration rate to sodium. The high temperature and high pressure in the cover gas due to the decay heat of fission products including cesium cause the leakage of cesium to the outside of reactor vessel. However the exact migration rate of cesium to sodium has not been reported because of difficulty on the evaluation of the interfacial area of large gas bubble (Minges et al., 1986). In this study, we developed a cesium trapper composed of β”-alumina cylindrical container and a single-gas-bubble injector without wettability. We confirmed that a single argon gas bubble was steadily produced in our injector. Bhaga proposed the bubble shape region map, which correlates the bubble shape with Reynolds number, Eotvos number and Morton number of the bubble ejected into sodium pool. The bubble shapes were estimated to be always ellipsoidal. We could successfully confirmed that the liquid sodium can be separated from liquid sodium cesium mixture by using β”-alumina, whose separation rate was found to be calculated by the Faraday's law of electrolysis. (author)

  1. Cesium-plasma-conductivity enhancement in the advanced thermionic energy converter. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Manikopoulos, C.N.

    Two methods of plasma conductivity enhancement in a cesium vapor thermionic energy converter have been studied. The first involved resonance photoabsorption of several cesium lines and the second utilized cesium plasma sustenance by application of microwave power. An extensive study of ionization processes in a cesium discharge in the presence of resonance ionization was made. Calculations were made of expected percentage excitation levels for several cesium resonance transitions for different values of neutral density and temperature as well as incident radiation power levels. The results of some of these computations were tabulated. Several ionization schemes were considered. A number of cesium transitions were investigated in the range of 799 to 870 nanometers for four different cesium reservoir temperatures, 467, 511, 550 and 591 K. The related absorption coefficients of the radiation lines in the plasma were deduced and tabulated. The resulting plasma conductivity increase was recorded and the associated ionization enhancement was deduced. A microwave cavity was built where the emitter and collector of a simple thermionic converter made up two of the cavity walls and resonant microwave power was externally applied. The I-V characteristics of the thermionic converter were studied under several microwave power levels in the range of 0 to 2 watts. Significant shifts to higher currents were observed as the microwave power levels were raised. In conclusion, both methods show promise as auxiliary ionization mechanisms for the thermionic energy converter, especially at low emitter temperatures.

  2. Cesium-plasma-conductivity enhancement in the advanced thermionic energy converter. Final report

    International Nuclear Information System (INIS)

    Two methods of plasma conductivity enhancement in a cesium vapor thermionic energy converter have been studied. The first involved resonance photoabsorption of several cesium lines and the second utilized cesium plasma sustenance by application of microwave power. An extensive study of ionization processes in a cesium discharge in the presence of resonance ionization was made. Calculations were made of expected percentage excitation levels for several cesium resonance transitions for different values of neutral density and temperature as well as incident radiation power levels. The results of some of these computations were tabulated. Several ionization schemes were considered. A number of cesium transitions were investigated in the range of 799 to 870 nanometers for four different cesium reservoir temperatures, 467, 511, 550 and 591 K. The related absorption coefficients of the radiation lines in the plasma were deduced and tabulated. The resulting plasma conductivity increase was recorded and the associated ionization enhancement was deduced. A microwave cavity was built where the emitter and collector of a simple thermionic converter made up two of the cavity walls and resonant microwave power was externally applied. The I-V characteristics of the thermionic converter were studied under several microwave power levels in the range of 0 to 2 watts. Significant shifts to higher currents were observed as the microwave power levels were raised. In conclusion, both methods show promise as auxiliary ionization mechanisms for the thermionic energy converter, especially at low emitter temperatures

  3. Equilibrium, kinetic and thermodynamic study of cesium adsorption onto nanocrystalline mordenite from high-salt solution.

    Science.gov (United States)

    Lee, Keun-Young; Park, Minsung; Kim, Jimin; Oh, Maengkyo; Lee, Eil-Hee; Kim, Kwang-Wook; Chung, Dong-Yong; Moon, Jei-Kwon

    2016-05-01

    In this study, the equilibrium, kinetics and thermodynamics of cesium adsorption by nanocrystalline mordenite were investigated under cesium contamination with high-salt solution, simulating the case of an operation and decommissioning of nuclear facilities or an accident during the processes. The adsorption rate constants were determined using a pseudo second-order kinetic model. The kinetic results strongly demonstrated that the cesium adsorption rate of nano mordenite is extremely fast, even in a high-salt solution, and much faster than that of micro mordenite. In the equilibrium study, the Langmuir isotherm model fit the cesium adsorption data of nano mordenite better than the Freundlich model, which suggests that cesium adsorption onto nano mordenite is a monolayer homogeneous adsorption process. The obtained thermodynamic parameters indicated that the adsorption involved a very stable chemical reaction. In particular, the combination of rapid particle dispersion and rapid cesium adsorption of the nano mordenite in the solution resulted in a rapid and effective process for cesium removal without stirring, which may offer great advantages for low energy consumption and simple operation. PMID:26683820

  4. Vitrification of spent organic ion exchange resins- 137Cesium volatility during oxidation

    International Nuclear Information System (INIS)

    Organic ion exchange (IX) resins are used to purify coolant water in nuclear power plants. The spent IX resins contain 137Cesium as major long-lived radioisotope. Their vitrification requires complete combustion of organic matter. 137Cesium volatility during their oxidation is most important factor for selection of oxidation procedure. Based on TGA studies, copper and vanadate catalysts were selected respectively for cationic and anionic IX resins to oxidise them at 500-700 degC. Experiments were conducted with 137Cesium and catalyst loaded cationic and anionic resins. About 56 to 60% 137Cesium was released from cationic resins in 3 hours. 137Cesium release from cationic resins could be brought down to 19 to 22% by addition of glass formers. The 137Cesium releases from anionic resins were nearly same for 2 hours heating. In absence of glass formers, the catalyst on anionic resins formed molten mass, which was difficult to remove. Experiment with one litre of 137Cesiuin loaded mixed cationic and anionic resins released 16.8% 137Cesium to off gases and formed a slag having specific gravity of 1.73 due to difficulty in oxidising last traces of carbon. The volume reduction factor achieved was 18.2 as against 68 expected for complete oxidation of IX resins. The higher volume reduction factor can be achieved by using improved oxidation procedure in scaling up studies. (author)

  5. possibilities of isotope separation of radioactive cesium by ion cyclotron resonance

    International Nuclear Information System (INIS)

    The transmutation of radioactive wastes is of high interest in order to reduce as much as possible the difficulties induced by their storage. In the case of radioactive cesium waste, cesium 137 which presents a short life time (30 years) is difficult to handle due to its high thermal load and and radiation level; cesium 135 is a long life time isotope with high mobility in storage glasses. As the processes of transmutation are different for cesium 135 and cesium 137 and as the neutron consumption is very high, it would be necessary to proceed to a preliminary isotope separation and it would not be worth to transmute the stable 133 isotope of cesium. Peculiar problems linked with cesium physico-chemical properties such as ionisation rat, vapour pressure, cooling of the components of the separation elements, especially the collector part, are discussed. It is shown that a high density plasma (1012 cm -3), with low ionic temperature (1 eV), good for isotope separation, can be achieved easily. It must be noticed that the cooling with water has to be avoided due to chemical reactions. After having defined the unitary separative element, different enrichment strategies and arrangements of the separative elements are proposed. An economic estimation with our code RICAN is given. (author)

  6. Main Group Lewis Acid-Mediated Transformations of Transition-Metal Hydride Complexes.

    Science.gov (United States)

    Maity, Ayan; Teets, Thomas S

    2016-08-10

    This Review highlights stoichiometric reactions and elementary steps of catalytic reactions involving cooperative participation of transition-metal hydrides and main group Lewis acids. Included are reactions where the transition-metal hydride acts as a reactant as well as transformations that form the metal hydride as a product. This Review is divided by reaction type, illustrating the diverse roles that Lewis acids can play in mediating transformations involving transition-metal hydrides as either reactants or products. We begin with a discussion of reactions where metal hydrides form direct adducts with Lewis acids, elaborating the structure and dynamics of the products of these reactions. The bulk of this Review focuses on reactions where the transition metal and Lewis acid act in cooperation, and includes sections on carbonyl reduction, H2 activation, and hydride elimination reactions, all of which can be promoted by Lewis acids. Also included is a section on Lewis acid-base secondary coordination sphere interactions, which can influence the reactivity of hydrides. Work from the past 50 years is included, but the majority of this Review focuses on research from the past decade, with the intent of showcasing the rapid emergence of this field and the potential for further development into the future. PMID:27164024

  7. Preparation and chemical crystallographic study of new hydrides and hydro-fluorides of ionic character

    International Nuclear Information System (INIS)

    Within the context of a growing interest in the study of reversible hydrides with the perspective of their application in hydrogen storage, this research thesis more particularly addressed the case of ternary hydrides and fluorides, and of hydro-fluorides. The author reports the development of a method of preparation of alkaline hydrides, of alkaline earth hydrides and of europium hydride, and then the elaboration of ternary hydrides. He addresses the preparation of caesium fluorides and of calcium or nickel fluorides, of Europium fluorides, and of ternary fluorides. Then, he addresses the preparation of hydro-fluorides (caesium, calcium, europium fluorides, and caesium and nickel fluorides). The author presents the various experimental techniques: chemical analysis, radio-crystallographic analysis, volumetric mass density measurement, magnetic measurements, ionic conductivity measurements, Moessbauer spectroscopy, and nuclear magnetic resonance. He reports the crystallographic study of some ternary alkaline and alkaline-earth hydrides (KH-MgH2, RbH-CaH2, CsH-CaH2, RbH-MgH2 and CsH-MgH2) and of some hydro-fluorides (CsCaF2H, EuF2H, CsNiF2H)

  8. Hydride blister formation in Zr-2.5wt%Nb pressure tube alloy

    International Nuclear Information System (INIS)

    Hydride blisters were grown over a period of 5-91 days under controlled thermal boundary condition using Zr-2.5wt%Nb pressure tube sections. Rectangular plate type specimens were hydrided to hydrogen concentration in the range of 20-250 ppm by weight and homogenized at 400 deg. C. These specimens were held in a specially fabricated jig capable of producing the required thermal gradients. The bulk specimen and the cold spot temperatures were maintained in the range of 270-400 deg. C and 40-100 deg. C respectively. Depending on the thermal gradients employed, two types of blister morphology were identified. The type I blister was single, round and located at the cold spot region whereas the type II blister consisted of several small blisters along a ring around the cold spot. Microstructural examination of the blister cross-section revealed three regions; a single-phase region consisting of hydrides, a region consisting of matrix containing both radial and circumferential hydrides, and another region consisting of matrix and circumferential hydrides. An attempt was made to rationalize the observed radial-circumferential hydride platelet orientation. Hydride blister growth rates were found to vary strongly with hydrogen concentration and bulk specimen temperature. The observed time for blister growth was found to be in agreement with the Sawatzky's model

  9. Characterisation of hydride blister in reactor operated zircaloy-2 pressure tube

    International Nuclear Information System (INIS)

    Zircaloy-2 pressure tubes pickup Hydrogen species (H and D) during in-reactor service. The hydrogen pickup leads to hydride precipitation and in the event of a contact between the pressure tube and the calandria tube, hydrogen migrates to the cold spot leading to the formation of hydride blister. One such hydride blister location in an operated Zircaloy-2 pressure tube of RAPS-2 was subjected to metallographic studies and mapping of the microstructure across the tube thickness. Mapping of the hydrogen concentration across the tube thickness was carried out by careful sampling and H estimation by DSC technique. The H profile across the tube thickness, up to the blister boundary, was generated. The hydride blister region was found to be made up of microstructurally different regions starting from dense massive hydride at the outer surface and followed in sequence by a region with dense and thick platelets oriented parallel to the blister boundary and radial platelet region, which subsequently merged with the background platelet distribution appropriate for the average hydrogen content of the pressure tube. The equivalent blister depth corresponding to H content of 16,000 w/ppm has been estimated from the H profile at the blister location. In the case of a hydride blister with measured thickness of 0.4mm the equivalent blister thickness was found to be 0.414mm. Mapping of the hardness of the massive hydride and the adjoining microstructurally different regions was carried out by microhardness measurements at room temperature. (author)

  10. The role of stress-state on the deformation and fracture mechanism of hydrided and non-hydrided Zircaloy-4

    Science.gov (United States)

    Cockeram, B. V.; Hollenbeck, J. L.

    2015-12-01

    Zircaloy-4 was tested at room-temperature over a range of hydrogen content between 10 and 200 ppm, and stress-states between a triaxiality of -0.23 and 0.9. Triaxiality (η) is defined as the ratio of hydrostatic stress to von Mises stress and was controlled through use of select mechanical test specimen designs. Testing of smooth and notched tensile specimens (η = 0.33 to 0.9) results in an increase in the stress to initiate plastic deformation and a decrease in strain to failure at higher values of η. Increases in triaxiality are shown to have a more significant effect on reducing the strain to failure when the material is hydrided. Increases in strain to failure are observed at lower values of triaxiality for dual keyhole specimens (η = 0.1) and compression specimens (η = -0.17 to -0.23), with hydrided material showing much less decrement in strain to failure at these lower triaxialities. Examinations of microstructure are used to show that a change in mechanism for deformation and fracture with triaxiality can explain these differences in mechanical behavior and a model is developed to describe the observed changes in strain to failure with stress-state.

  11. Effect of thermo-mechanical cycling on zirconium hydride reorientation studied in situ with synchrotron X-ray diffraction

    International Nuclear Information System (INIS)

    The circumferential hydrides normally present in nuclear reactor fuel cladding after reactor exposure may dissolve during drying for dry storage and re-precipitate when cooled under load into a more radial orientation, which could embrittle the fuel cladding. It is necessary to study the rates and conditions under which hydride reorientation may happen in order to assess fuel integrity in dry storage. The objective of this work is to study the effect of applied stress and thermal cycling on the hydride morphology in cold-worked stress-relieved Zircaloy-4 by combining conventional metallography and in situ X-ray diffraction techniques. Metallography is used to study the evolution of hydride morphology after several thermo-mechanical cycles. In situ X-ray diffraction performed at the Advanced Photon Source synchrotron provides real-time information on the process of hydride dissolution and precipitation under stress during several thermal cycles. The detailed study of diffracted intensity, peak position and full-width at half-maximum provides information on precipitation kinetics, elastic strains and other characteristics of the hydride precipitation process. The results show that thermo-mechanical cycling significantly increases the radial hydride fraction as well as the hydride length and connectivity. The radial hydrides are observed to precipitate at a lower temperature than circumferential hydrides. Variations in the magnitude and range of hydride strains due to reorientation and cycling have also been observed. These results are discussed in light of existing models and experiments on hydride reorientation. The study of hydride elastic strains during precipitation shows marked differences between circumferential and radial hydrides, which can be used to investigate the reorientation process

  12. A New Pumping-Probing Scheme for the Optically Pumped Cesium Beam Frequency Standard

    Institute of Scientific and Technical Information of China (English)

    陈景标; 朱程锦; 王凤芝; 杨东海

    2001-01-01

    A new pumping-probing scheme for the optically pumped cesium beam frequency standard has been experimentally tested in our laboratory. The stability of the optically pumped cesium beam frequency standard was measured by comparing its 10 MHz output with an HP5071A commercial cesium atomic clock. The result shows that the frequency stability for the 1 s and 30000s sample times are 1.2 × 10-11 and 3.7 × 10-13, respectively. It was proved that the new pumping scheme works well.

  13. A new ion exchanger for the removal of cesium from aqueous solutions

    International Nuclear Information System (INIS)

    A new exchange potassium copper nickel hexacyanoferrates(II) was prepared. It was characterized by chemical composition and surface area measurements. The removal of cesium from aqueous solution by ion exchange was studied as function of shaking time. pH and concentration of acids, salts and cesium. The data indicates high value of distribution coefficient over a wide range of pH, nitric and hydrochloric acids concentration and in the presence of higher concentration of Na and K ions. A potassium copper nickel hexacyanoferrate(II) column was also tested for elution of cesium using 8 M ammonium nitrate solution. (author)

  14. Application of Cesium isotopes in daily life; Aplicacoes dos isotopos do Cesio no cotidiano

    Energy Technology Data Exchange (ETDEWEB)

    Jordao, B.O.; Quaresma, D.S.; Carvalho, R.J., E-mail: bjordan@on.br, E-mail: dansq@on.br, E-mail: carvalho@on.br [Observatorio Nacional (ON/LPTF), Rio de Janeiro, RJ (Brazil). Lab. Nacional de Tempo e Frequencia; Peixoto, J.G.P., E-mail: guilherm@ird.gov.br [Instituto de Radioprotecao e Dosimetria, (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil). Lab. de Metrologia das Radiacoes Ionizantes

    2014-07-01

    In the world of science, the desire of the scientific community to discover new chemical elements is crucial for the development of new technologies in various fields of knowledge. And the main chemical element addressed by this article is Cesium, but specifically {sup 133}Cesium isotope and radioisotope {sup 137}Cesium, exemplifying their physical and chemical characteristics, and their applications. This article will also show how these isotopes have provided researchers a breakthrough in the field of radiological medicine and in time and frequency metrology. (author)

  15. Cesium leaching from {gamma}-irradiated CsA and CsX zeolites

    Energy Technology Data Exchange (ETDEWEB)

    Lima, Enrique [Universidad Autonoma Metropolitana, Iztapalapa, A. P. 55-532, Av. San Rafael Atlixco No. 186 Col. Vicentina, 09340 Mexico, D.F. (Mexico)], E-mail: lima@xanum.uam.mx; Ibarra, Ilich A.; Lara, Victor [Universidad Autonoma Metropolitana, Iztapalapa, A. P. 55-532, Av. San Rafael Atlixco No. 186 Col. Vicentina, 09340 Mexico, D.F. (Mexico); Bosch, Pedro [Instituto de Investigaciones en Materiales, A. P. 70-360, Universidad Nacional Autonoma de Mexico, Circuito Exterior, Ciudad Universitaria, 04510 Mexico, D.F. (Mexico); Bulbulian, Silvia [Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, Col. Escandon, Delegacion Miguel Hidalgo, 11801 Mexico, D.F. (Mexico)

    2008-12-30

    The present study discusses the effect of {gamma}-irradiation on Cs{sup +}-exchanged X and A zeolites. The incorporation of Cs{sup +} ions into A and X zeolites was performed using three different cesium salts (chloride, nitrate or acetate). Cs{sup +} ions immobilized into the vitrified zeolites by thermal treatment are located in different sites of the zeolite networks. It is found that {gamma}-irradiation favors cesium retention depending on the cesium precursor salt used in the cationic exchange step.

  16. Specific interaction of cesium with the surface of calcium silicate hydrates

    International Nuclear Information System (INIS)

    The sorption of cesium at the calcium silicate hydrates (CSH) surface was investigated, both through sorption isotherm data and by solid-state NMR experiments. The sorption ability of CSH towards cesium is favored for low solid Ca/Si molar ratios, in agreement with the negative surface charge they develop then. A significant proportion of these sorbed cesium cations remains tightly bound to the surface sites forming, in dehydrated CSH, inner-sphere complexes, which can not be removed by alcohol washing. Chloride seems to present a lower affinity for CSH, even for high Ca/Si molar ratios, where the surface charge becomes positive. (orig.)

  17. First-principles study of cesium adsorption to weathered micaceous clay minerals

    Science.gov (United States)

    Okumura, Masahiko; Nakamura, Hiroki; Machida, Masahiko

    2014-05-01

    A large amount of radioactive nuclides was produced into environment due to the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident. Residents near FDNPP were suffering from radioactive cesium and then evacuated, because which has long half-life and is retained by surface soil for long time. The Japanese government has been decontaminating the cesium by removing the surface soil in order to return them to their home. This decontamination method is very effective, but which produces huge amount of waste soil. This becomes another big problem in Fukushima, because it is not easy to find large storage sites. Then effective and economical methods to reduce the volume of the waste soil are needed. However, it has not been invented yet. One of the reasons is lack of knowledge about microscopic process of adsorption/desorption of cesium to/from soil. It is known that weathered micaceous clay minerals play crucial role on adsorption and retention of cesium. They are expected to have special sorption sites, called frayed edge sites (FESs), which adsorb cesium selectively and irreversibly. Properties of FES have been intensely investigated by experiments. But microscopic details of the adsorption process on FES are still unclear. Because direct observation of the process with current experimental techniques is quite difficult. We investigated the adsorption of cesium to FES in muscovite, which is a typical micaceous clay mineral, via first-principles calculations (density functional theory). We made a minimal model of FES and evaluate the energy difference before and after cesium adsorption to FES. This is the first numerical modeling of FES. It was shown that FES does adsorb cesium if the weathering of muscovite has been weathered. In addition, we revealed the mechanism of cesium adsorption to FES, which is competition between ion radius of cesium and the degree of weathering. I plan to discuss volume reduction of the waste soil based on our result. Reference M. Okumura

  18. High voltage holding in the negative ion sources with cesium deposition

    Energy Technology Data Exchange (ETDEWEB)

    Belchenko, Yu.; Abdrashitov, G.; Ivanov, A.; Sanin, A.; Sotnikov, O., E-mail: O.Z.Sotnikov@inp.nsk.su [Budker Institute of Nuclear Physics, Siberian Branch of Russian Academy of Sciences, Novosibirsk (Russian Federation)

    2016-02-15

    High voltage holding of the large surface-plasma negative ion source with cesium deposition was studied. It was found that heating of ion-optical system electrodes to temperature >100 °C facilitates the source conditioning by high voltage pulses in vacuum and by beam shots. The procedure of electrode conditioning and the data on high-voltage holding in the negative ion source with small cesium seed are described. The mechanism of high voltage holding improvement by depletion of cesium coverage is discussed.

  19. Test procedures and instructions for single shell tank saltcake cesium removal with crystalline silicotitanate

    Energy Technology Data Exchange (ETDEWEB)

    Duncan, J.B.

    1997-01-07

    This document provides specific test procedures and instructions to implement the test plan for the preparation and conduct of a cesium removal test, using Hanford Single Shell Tank Saltcake from tanks 24 t -BY- I 10, 24 1 -U- 108, 24 1 -U- 109, 24 1 -A- I 0 1, and 24 t - S-102, in a bench-scale column. The cesium sorbent to be tested is crystalline siticotitanate. The test plan for which this provides instructions is WHC-SD-RE-TP-024, Hanford Single Shell Tank Saltcake Cesium Removal Test Plan.

  20. Increasing the Space Charge Limit and Other Effects of Cesium Seeding in Hydrogen Negative Ion Sources

    International Nuclear Information System (INIS)

    The role of cesium seeding in increasing the negative ion current in volume sources is described. By a reduction in the local plasma potential the current of extracted electrons is vastly reduced. As a result, cesium increases the fraction of the transverse space charge limit available to the ions by as much as a factor of three. In addition, cesium can increase the total space charge limit by injection of Cs+ into the presheath-a newly recognized phenomenon consistent with experimental measurements and determined from application of a Double-Vlasov model for negative ion extraction

  1. Investigation of adsorption and wetting of 3He on cesium and cesiated glass

    International Nuclear Information System (INIS)

    Experiments have been carried out to investigate the binding of 3He on cesium substrates, using optical pumping to spin-polarize the atoms. The behavior of 3He on the walls at low temperature can be analyzed through the evolution of the nuclear magnetization of the sample. Preliminary results are presented, including: (1) adsorption studies of gaseous 3He on cesiated glass; (2) magnetic relaxation time of polarized liquid 3He on cesium and cesiated glass; (3) evidence for wetting of liquid 3He on cesium. 8 refs., 2 figs

  2. Hydride re-orientation in Zircaloy and its effect on the tensile properties. Revised edition

    International Nuclear Information System (INIS)

    Based on literature studies and experimental work, investigations were carried out to determine the stress and thermal conditions required for the reorientation of hydrides from an initial circumferential orientation to a radial one. The section of microscopic reference was transverse, in hydride ring samples of Zircaloy. It was found that, both the degree of reorientation and the relative amount of radial hydrides achieved, were dependent on the hydrogen content of the material, given the same stress and thermal conditions. The need to take most of the hydrides into solution at the uppermost temperature of the thermal cycle, in order for complete reorientation to occur, became also clear. In general, an upper temperature of 500 deg C, in combination with an orientation stress in the interval 150-200 MPa was found to be adequate for the reorientation to radial hydrides. On the basis of these initial results, attempts were then made to produce ring test samples in which the hydrides had assumed the radial orientation. These were subsequently subjected to the tensile test in order to investigate the effect of hydride reorientation on the tensile properties of the material. The tests, which were conducted at room temperature and higher temperatures (100 deg C - 300 deg C), showed that the hydrides were brittle at room temperature but became less so at higher temperatures. With the exception of the samples which were tested at room temperature, all the other samples did show a ductile failure. At the strain rate employed in the present work (0.02cm/mm) therefore, the radial hydrides could not be said to have a reducing effect on the ductile characteristics of Zircaloy at higher temperatures

  3. Small Angle Neutron Scattering Investigation of Hydride Precipitations in Zircaloy-4

    International Nuclear Information System (INIS)

    The precipitation and annealing behavior of hydrogen in Zircaloy-4 was investigated by means of small angle neutron scattering. The results show that already during cool down in the air lock of the applied furnace zirconium hydride precipitates are formed. The size of the hydrides seems to be greater than the upper detection limit of the SANS experiments performed. These hydrides seem to be stable during various annealing at temperatures between 573 and 773 K for 1 to 16 days in inert atmosphere. (author)

  4. Thermal decomposition kinetics of titanium hydride and Al alloy melt foaming process

    Institute of Scientific and Technical Information of China (English)

    YANG; Donghui; HE; Deping; YANG; Shangrun

    2004-01-01

    A temperature programmed decomposition (TPD) apparatus with metal tube structure, in which Ar is used as the carrier gas, is established and the TPD spectrum of titanium hydride is acquired. Using consulting table method (CTM), spectrum superposition method (SSM) and differential spectrum technique, TPD spectrum of titanium hydride is separated and a set of thermal decomposition kinetics equations are acquired. According to these equations, the relationship between decomposition quantity and time for titanium hydride at the temperature of 940 K is obtained and the result well coincides with the Al alloy melt foaming process.

  5. Rapid Microwave Synthesis, Characterization and Reactivity of Lithium Nitride Hydride, Li4NH

    OpenAIRE

    Nuria Tapia-Ruiz; Natalie Sorbie; Nicolas Vaché; Hoang, Tuan K. A.; Gregory, Duncan H.

    2013-01-01

    Lithium nitride hydride, Li4NH, was synthesised from lithium nitride and lithium hydride over minute timescales, using microwave synthesis methods in the solid state for the first time. The structure of the microwave-synthesised powders was confirmed by powder X-ray diffraction [tetragonal space group I41/a; a = 4.8864(1) Å, c = 9.9183(2) Å] and the nitride hydride reacts with moist air under ambient conditions to produce lithium hydroxide and subsequently lithium carbonate. Li4NH undergoes n...

  6. Proton beam production by a laser ion source with hydride target

    Energy Technology Data Exchange (ETDEWEB)

    Okamura, M., E-mail: okamura@bnl.gov [Collider-Accelerator Department, Brookhaven National Laboratory, Upton, New York 11973 (United States); Nishina Center for Accelerator-Based Science, RIKEN, Saitama (Japan); Stifler, C. [Engineering Physics Systems Department, Providence College, Providence, Rhode Island 02918 (United States); Palm, K. [Department of Physics, Cornell University, Ithaca, New York 14853 (United States); Steski, D.; Kanesue, T. [Collider-Accelerator Department, Brookhaven National Laboratory, Upton, New York 11973 (United States); Ikeda, S. [Nishina Center for Accelerator-Based Science, RIKEN, Saitama (Japan); Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, Kanagawa (Japan); Kumaki, M. [Nishina Center for Accelerator-Based Science, RIKEN, Saitama (Japan); Research Institute for Science and Engineering, Waseda University, Tokyo (Japan)

    2016-02-15

    We studied proton beam production from a laser ion source using hydrogen rich target materials. In general, gas based species are not suitable for laser ion sources since formation of a dense laser target is difficult. In order to achieve reliable operation, we tested hydride targets using a sub nanosecond Q-switched Nd-YAG laser, which may help suppress target material consumption. We detected enough yields of protons from a titanium hydride target without degradation of beam current during the experiment. The combination of a sub nanosecond laser and compressed hydride target may provide stable proton beam.

  7. Generalized computational model for high-pressure metal hydrides with variable thermal properties

    DEFF Research Database (Denmark)

    Mazzucco, Andrea; Rokni, Masoud

    2015-01-01

    This study considers a detailed 1D fueling model applied to a metal hydride system, with Ti1.1CrMn as the absorbing alloy, to predict the weight fraction of the absorbed hydrogen and the solid bed temperature. Dependencies of thermal conductivity and specific heat capacity upon pressure and...... hydrogen content, respectively, are accounted for by interpolating experimental data. The effect of variable parameters on the critical metal hydride thickness is investigated and compared to results obtained from a constant-parameter analysis. Finally, the discrepancy in the metal hydride thickness value...

  8. The storage of hydrogen in the form of metal hydrides: An application to thermal engines

    Science.gov (United States)

    Gales, C.; Perroud, P.

    1981-01-01

    The possibility of using LaNi56, FeTiH2, or MgH2 as metal hydride storage sytems for hydrogen fueled automobile engines is discussed. Magnesium copper and magnesium nickel hydrides studies indicate that they provide more stable storage systems than pure magnesium hydrides. Several test engines employing hydrogen fuel have been developed: a single cylinder motor originally designed for use with air gasoline mixture; a four-cylinder engine modified to run on an air hydrogen mixture; and a gas turbine.

  9. Behaviour of depleted uranium as metal hydride in a storage vessel

    International Nuclear Information System (INIS)

    Full text: The storage of hydrogen isotopes as metal hydrides is considered a safe and modern technique. The metal hydrides offer a great opportunity for improvement of tritium processing. They allow the design of safe, compact and efficient tritium handling equipment. The paper presents our experience in developing a technology of making experimental hydride storage vessels for tritium handling and processing. The vessel, using depleted uranium as metallic matrix, was tested to determine the experimental conditions for activation, loading and desorption hydrogen. Using depleted uranium, a hydrogen/metal ratio (H/Me) of 2.9 could be achieved. The equipment was tested by successive absorption/desorption cycles. (authors)

  10. Proton beam production by a laser ion source with hydride target

    International Nuclear Information System (INIS)

    We studied proton beam production from a laser ion source using hydrogen rich target materials. In general, gas based species are not suitable for laser ion sources since formation of a dense laser target is difficult. In order to achieve reliable operation, we tested hydride targets using a sub nanosecond Q-switched Nd-YAG laser, which may help suppress target material consumption. We detected enough yields of protons from a titanium hydride target without degradation of beam current during the experiment. The combination of a sub nanosecond laser and compressed hydride target may provide stable proton beam

  11. Thermodynamics and statistical mechanics of some hydrides of the lanthanides and actinides

    International Nuclear Information System (INIS)

    This work deals mainly with the thermodynamic and physical properties of the hydrides of the lanthanides and actinides. In addition, statistical models have been developed and applied to metal-hydrogen systems. A kinetic study of the uranium-hydrogen system was performed. The thermodynamic properties of the hydrides of neptunium, thorium, praseodymium, neodymium, samarium and europium were determined. In addition the samarium-europium-hydrogen ternary system was investigated. Moessbauer effect measurements of cubic neptunium hydrides were interpreted according to a model presented. A comparison. (author)

  12. Analytical control of production of As, P, Si, B hydrides and the mixtures on their basis

    International Nuclear Information System (INIS)

    Highly sensitive and selective detectors which are in the basis of some analytical devices, such as chromatograph Tzvet 500G attachment POU-80, gigrometer Enisej gas analyzer Platon that permit to control the production of As, P, Si, B hydrides, are tested. The techniques of tetermination of constant gases, general carbon, moisture in the mixtures based on As, P, Si, B hydrides with diluting gases (H2, He, Ar) as well as hydrides in them and in the air of working premises, are suggested

  13. Determinations of cesium-134, cesium-137 and potassium-40 as a measure of intrauterine exposure to rays and contamination of human milk after the Chernobyl reactor accident

    International Nuclear Information System (INIS)

    In order to gain better insights into the degree of intrauterine exposure to rays after the Chernobyl reactor accident, placental measurements of the activity levels of cesium-134 and cesium-137 were carried out in 125 expectant mothers from the Munich area using four thallium-activated sodium iodine crystal detectors. The lower limit of detection determined for this technique was 1-2 bq/kg. Parallel tests were performed on human milk samples to establish their contents of cesium-137 and potassium-40. The ultrapure germanium detector used for this purpose measured levels down to a detection threshold of 1 bq/l. In a total of 13 placentae (10 %) and 56 milk samples (57%) the activity of cesium-137 was found to be so low as to preclude detection. The highest values measured were 18.6 bq/kg for the placentae and 10.6 bq/l for the milk samples. The activity concentrations of potassium-40 were frequently seen to exceed those of cesium-137, the highest value determined here being 73.6 bq/l. The author has come to the conclusion that the alleged increases in radiation levels remain within the range of variations generally expected to occur with natural radiation. Mothers are not discouraged from breast-feeding, even though their attention must be drawn to the fact that the rates of malignant diseases and genetic damage tend to rise on a global scale. (KST)

  14. Diffusion of water, cesium and neptunium in pores of rocks

    International Nuclear Information System (INIS)

    Teollisuuden Voima Oy (TVO) is investigating the feasibility to dispose of spent nuclear fuel within Finland. The present plan calls for the repository to be located in crystalline rock at a depth of several hundred meters. The safety assessment of the repository includes calculations of migration of waste nuclides. The flow of waste elements in groundwater will be retarded through sorption interaction with minerals and through diffusion into rock. Diffusion is the only mechanism retarding the migration of non-sorbing species and, it is expected to be the dominating retardation mechanism of many of the sorbing elements. In the investigation the simultaneous diffusion of tritiated water (HTO), cesium and neptunium in rocks of TVO investigation sites at Kivetty, Olkiluoto and Romuvaara were studied. (11 refs., 33 figs., 9 tabs.)

  15. Cesium-137 accident lessons in Goiania, Goias State, Brazil

    International Nuclear Information System (INIS)

    This document relates the experience obtained by several professionals which had an important role in the cesium-137 accident occurred in Goiania, Goias State, Brazil in September, 1987. It's divided into chapters, according to the action area - medical, nursing, social assistance, odontological and psychological. At first, some notions of radioprotection are explained, followed by the accident history and by the doctors and nurses action during the emergency phase and the medical, odontological, social and psychological assistance to the victims. The social assistance report shows some statistical data about the economic, occupational and social conditions of the accident victims. It is shown some information about the health institutions and the sanitary care in the ionizing radiation and about the occupational radiological protection in Goiania

  16. Coherence properties of nanofiber-trapped cesium atoms

    CERN Document Server

    Reitz, D; Mitsch, R; Schneeweiss, P; Rauschenbeutel, A

    2013-01-01

    We experimentally study the ground state coherence properties of cesium atoms in a nanofiber-based two-color dipole trap, localized 200 nm away from the fiber surface. Using microwave radiation to coherently drive the clock transition, we record Ramsey fringes as well as spin echo signals and infer a reversible dephasing time $T_2^\\ast=0.6$ ms and an irreversible dephasing time $T_2^\\prime=3.7$ ms. By theoretically modelling the signals, we find that, for our experimental parameters, $T_2^\\ast$ and $T_2^\\prime$ are limited by the finite initial temperature of the atomic ensemble and the heating rate, respectively. Our results represent a fundamental step towards establishing nanofiber-based traps for cold atoms as a building block in an optical fiber quantum network.

  17. Coherence Properties of Nanofiber-Trapped Cesium Atoms

    Science.gov (United States)

    Reitz, D.; Sayrin, C.; Mitsch, R.; Schneeweiss, P.; Rauschenbeutel, A.

    2013-06-01

    We experimentally study the ground state coherence properties of cesium atoms in a nanofiber-based two-color dipole trap, localized ˜200nm away from the fiber surface. Using microwave radiation to coherently drive the clock transition, we record Ramsey fringes as well as spin echo signals and infer a reversible dephasing time of T2*=0.6ms and an irreversible dephasing time of T2'=3.7ms. By modeling the signals, we find that, for our experimental parameters, T2* and T2' are limited by the finite initial temperature of the atomic ensemble and the heating rate, respectively. Our results represent a fundamental step towards establishing nanofiber-based traps for cold atoms as a building block in an optical fiber quantum network.

  18. Trade study for the disposition of cesium and strontium capsules

    International Nuclear Information System (INIS)

    This trade study analyzes alternatives for the eventual disposal of cesium and strontium capsules currently stored at the Waste Encapsulation and Storage Facility as by-product. However, for purposes of this study, it is assumed that at some time in the future, the capsules will be declared high-level waste and therefore will require disposal at an offsite geologic repository. The study considered numerous alternatives and selected three for detailed analysis: (1) overpack and storage at high-level waste canister storage building, (2) overpack at the high-level waste vitrification facility followed by storage at a high-level waste canister storage building, and (3) blend capsule contents with other high-level waste feed streams and vitrify at the high-level waste vitrification facility

  19. Norbadione A: synthetic approach and cesium complexation studies

    International Nuclear Information System (INIS)

    This work was dedicated to the study of the synthesis and complexation studies of norbadione A: a pigment originating from a mushroom. A synthetic approach, based on a double Suzuki-Miyaura coupling, was developed. This strategy was applied with high yields to the synthesis of various norbadione A analogues, as well as to the synthesis of simple pulvinic acids. Access to functionalized precursors of the molecule was also studied and the final coupling remains to be done. Besides, a speciation study based on electro-spray ionization mass spectrometry was conducted with norbadione A and one of the analogues. This study allowed the assessment of the cesium complexation abilities of each molecule. Structural data was also obtained and complexation constants were calculated. Finally, norbadione A and various synthetic products have been tested via high-throughput screening methods and strong antioxidant properties were observed. Other biological results are also reported. (author)

  20. Comparative study of cesium adsorption on dioctahedral and trioctahedral smectites

    International Nuclear Information System (INIS)

    Bentonites which are characterized by good rheological, mineralogical and chemical stability is considered used as sealing barriers in multibarrier Slovak system of deep geological repository for high-level radioactive waste and spent nuclear fuel. In Slovak Republic there are several significant deposits of bentonite, which are characterized by appropriate adsorption properties and meet the geotechnical requirements for this type of barriers. Study of adsorption properties of bentonites and other smectites is an essential step for developing the migration model long-lived corrosion and activation products, and fission products of uranium. Nuclear wastes contain the most important nuclear fission products, radioisotopes 134Cs and 137Cs. The present paper investigates and compares the cesium adsorption properties of Slovak and North America bentonites composed mainly of dioctahedral smectite montmorillonite (J, L, SAz-1 and STx-1) and trioctahedral smectites saponite (SapCa-2) and hectorite (SHCa-1). (author)