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Sample records for dehydridation

  1. Ductile zirconium powder by hydride-dehydride process

    Energy Technology Data Exchange (ETDEWEB)

    Krishnan, T S [BHABHA ATOMIC RESEARCH CENTRE, BOMBAY (INDIA); CHAUDHARY, S [NUCLEAR FUEL COMPLEX, HYDERABAD (INDIA)

    1976-09-01

    The preparation of ductile zirconium powder by the hydride-dehydride process has been described. In this process massive zirconium obtained from Kroll reduction of ZrCl/sub 4/ is first rendered brittle by hydrogenation and the hydride crushed and ground in a ball mill to the required particle size. Hydrogen is then hot vacuum extracted to yield the metal powder. The process has been successfully employed for the production of zirconium powders with low oxygen content and having hardness values in the range of 115-130 BHN, starting from a zirconium sponge of 100-120 BHN hardness. Influence of surface characteristics of the starting metal on its hydriding behaviour has been studied and the optimum hydriding-dehydriding conditions established.

  2. Dehydriding and rehydriding reactions of LiBH4

    International Nuclear Information System (INIS)

    Orimo, S.; Nakamori, Y.; Kitahara, G.; Miwa, K.; Ohba, N.; Towata, S.; Zuettel, A.

    2005-01-01

    Structural differences in LiBH 4 before and after the melting reaction at approximately 550-bar K were investigated to clarify the experimental method for the confirmation of reversible dehydriding and rehydriding reactions. Since the long-range order of LiBH 4 begins to disappear after the melting reaction was achieved, investigation of the atomistic vibrations of the [BH 4 ]-anion in LiBH 4 was found to be effective for the confirmation of the reversibility. In the present study, LiBH 4 was successively dehydrided (decomposed) into LiH and B under 1-bar MPa of hydrogen at 873-bar K, and then rehydrided (recombined) into LiBH 4 under 35-bar MPa of hydrogen at the same temperature (873-bar K). The temperatures at the beginning and ending of the dehydriding reaction are lowered, by approximately 30-bar K, for LiBH 4 substituted (or mixed) with Mg (atomic ratio of Li:Mg=9:1) as compared to those for LiBH 4 alone. This is similar to the tendency exhibited by LiNH 2

  3. Hydriding and dehydriding properties of CaSi

    International Nuclear Information System (INIS)

    Aoki, Masakazu; Ohba, Nobuko; Noritake, Tatsuo; Towata, Shin-ichi

    2005-01-01

    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

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

    Energy Technology Data Exchange (ETDEWEB)

    Pasqualini, E. E.; Garcia, J.H.; Lopez, M.; Cabanillas, E.; Adelfang, P. [Dept. Combustibles Nucleares. Comision Nacional de Energia Atomica, Av. Gral. Paz 1499, 1650 Buenos Aires (Argentina)

    2002-07-01

    Uranium-molybdenum (U-Mo) alloys can be hydrided massively in metastable {gamma} (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)

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

    International Nuclear Information System (INIS)

    Pasqualini, E. E.; Garcia, J.H.; Lopez, M.; Cabanillas, E.; Adelfang, P.

    2002-01-01

    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)

  6. Morphology study on the depleted uranium as hydriding/dehydriding cycles

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Dong-you, E-mail: dongyou@nfri.re.kr [National Fusion Research Institute, Daejeon (Korea, Republic of); Yun, Sei-Hun; Kang, Hyun-Goo; Chang, Min Ho; Oh, Yun Hee [National Fusion Research Institute, Daejeon (Korea, Republic of); Kang, Kweon Ho; Woo, Yoon Myung [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2016-11-01

    Depleted Uranium (DU) is one of the strongest candidates as a getter material of hydrogen isotopes in the nuclear fusion reactor. In this work, small DU lump specimen with 99.8% purity was prepared for observation of morphology variation as hydriding/dehydriding cycles. Hydriding/dehydriding of DU was carried out more than 10 cycles for powder preparation. The pulverized DU specimen was safely handled in the glove box under Argon gas condition to minimize contact with oxygen and humidity. The morphology change according to hydriding/dehydriding cycles was observed by visual cell reactor, optical microscope and scanning electron microscope. The first hydriding of the small DU sample has progressed slowly with surface enlargement and volume expansion as time passes. After third hydriding/dehydriding cycles, most of DU was pulverized. The powder fineness of DU developed as hydriding/dehydriding cycle progresses. But the agglomerates of fine DU particles were observed. It was confirmed that the DU particles exist as porous agglomerates. And the particle agglomerate shows poor fluidity and even has the cohesive force.

  7. Manufacturing and investigation of U-Mo LEU fuel granules by hydride-dehydride processing

    International Nuclear Information System (INIS)

    Stetskiy, Y.A.; Trifonov, Y.I.; Mitrofanov, A.V.; Samarin, V.I.

    2002-01-01

    Investigations of hydride-dehydride processing for comminution of U-Mo alloys with Mo content in the range 1.9/9.2% have been performed. Some regularities of the process as a function of Mo content have been determined as well as some parameters elaborated. Hydride-dehydride processing has been shown to provide necessary phase and chemical compositions of U-Mo fuel granules to be used in disperse fuel elements for research reactors. Pin type disperse mini-fuel elements for irradiation tests in the loop of 'MIR' reactor (Dmitrovgrad) have been fabricated using U-Mo LEU fuel granules obtained by hydride-dehydride processing. Irradiation tests of these mini-fuel elements loaded to 4 g U tot /cm 3 are planned to start by the end of this year. (author)

  8. Design of an integrated system to recycle Zircaloy cladding using a hydride–milling–dehydride process

    Energy Technology Data Exchange (ETDEWEB)

    Kelley, Randy, E-mail: rkelley@pitt.edu [Mechanical Engineering Department, 236 Engineering and Science Building, University of Pittsburgh – Johnstown, Johnstown, PA 15904 (United States); McDeavitt, Sean [Texas A and M University, Department of Nuclear Engineering, 327 Zachry Engineering Center, 3133 TAMU, College Station, TX 77843 (United States)

    2013-10-15

    Highlights: • Dehydriding zirconium hydride was studied at relatively low temperatures (<800 °C). • High vacuum pressures decrease dehydriding temperatures. • Specialized equipment was designed, built and demonstrated to process zirconium. • The process hydrided–milled–dehydrided zirconium metal to a fine metal powder. • Two powder samples were analyzed and proved the operation of the machine. -- Abstract: A hydride–dehydride process was evaluated to recover a portion of spent nuclear fuel cladding; a zirconium alloy (Zircaloy), as a metal powder that may be used for advanced nuclear fuel applications. The investigation was part of a broader study that sought to determine the viability of recovering components of used nuclear fuel to for a metal matrix cermet for transuranic burning. The zirconium powder process begins with the conversion of Zircaloy cladding hulls into a brittle zirconium hydride, which is easily pulverized into a powder. The dehydriding process removes hydrogen by heating the powder in a vacuum, resulting in a zirconium metal powder. In support of this, a specialized piece of equipment was designed to demonstrate the entire zirconium conversion process to transform Zircaloy tubes into metal powder without intermediate handling. This was accomplished by building a milling system that rotates inside of controlled atmosphere chamber with an internal heater. The hydriding process was accomplished using an argon–5% hydrogen atmosphere at 500 °C. The process variables for the dehydriding process were determined using a thermogavimetric analysis (TGA) method. It was determined that a rough vacuum (∼0.001 bar) and 800 °C were sufficient to decompose the zirconium hydride. Zirconium metal powder was created using different milling times: 45 min (coarse powder) and 12 h (fine powder). X-ray diffraction (XRD) analysis indicated that the process produced a zirconium metal. Additionally, visual observations of the samples silvery

  9. Transmission electron microscopy study of unhydrided,dehydrided and annealed LaNi5

    NARCIS (Netherlands)

    Veirman, de A.E.M.; Staals, A.A.; Notten, P.H.L.

    1994-01-01

    The influence of hydrogen absorption on the microstructure of LaNi5 powders has been investigated by transmission electron microscopy. At the surface of the unhydrided and dehydrided LaNi5 grains a reaction layer is observed. By means of selected area electron diffraction this layer is found to

  10. Development of laboratory apparatus dedicated to the study of hydride--dehydride reactions

    International Nuclear Information System (INIS)

    Wemple, R.P.; Kass, W.J.

    1979-07-01

    Hydrogen-compatible laboratory apparatus has been designed and developed to study hydride--dehydride reactions at elevated pressures and temperatures. The system has operated at pressures and temperatures up to 34 MPa and 550 0 C during experiments conducted on LiAlH 4 and NiZr. Instrumentation incorporated into the system also allows differential thermal analysis and acoustic emission data to be collected as the chemical reactions progress. 13 figures

  11. Hydriding and dehydriding characteristics of small-scale DU and ZrCo beds

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Dongyou; Lee, Jungmin; Koo, Daeseo [Korea Atomic Energy Research Institute, 989-111 Daedeokdaero, Yuseong, Daejeon 305-353 (Korea, Republic of); Chung, Hongsuk, E-mail: hschung1@kaeri.kr [Korea Atomic Energy Research Institute, 989-111 Daedeokdaero, Yuseong, Daejeon 305-353 (Korea, Republic of); Kim, Ki Hwan [Korea Atomic Energy Research Institute, 989-111 Daedeokdaero, Yuseong, Daejeon 305-353 (Korea, Republic of); Kang, Hyun-Goo; Chang, Min Ho [National Fusion Research Institute, 113 Gwahakro, Yuseong, Daejeon 305-333 (Korea, Republic of); Camp, Patrick [ITER Organization, Route de Vinon sur Verdon, 13115 Saint Paul Lez Durance (France); Jung, Ki Jung; Cho, Seungyon; Yun, Sei-Hun; Kim, Chang Shuk [National Fusion Research Institute, 113 Gwahakro, Yuseong, Daejeon 305-333 (Korea, Republic of); Yoshida, Hiroshi [Fusion Science Consultant, 3288-10 Sakado-cho, Mito-shi 310-0841, Ibakaki-ken (Japan); Paek, Seungwoo; Lee, Hansoo [Korea Atomic Energy Research Institute, 989-111 Daedeokdaero, Yuseong, Daejeon 305-353 (Korea, Republic of)

    2013-10-15

    Highlights: • We have designed and fabricated a twosome small-scale getter bed for a comparison of ZrCo with DU on the hydriding/dehydriding properties. • We provide preliminary experimental results of our ZrCo and DU beds. -- Abstract: With the development of fusion technology, it will be necessary to store large amounts of tritium during the nuclear fusion fuel cycle. Stable metal tritides are viewed as potential candidates for the high-density storage of tritium. Metal tritide formers offer a safe and convenient method for tritium storage. For the storage, supply, and recovery of hydrogen isotopes, zirconium cobalt (ZrCo) and depleted uranium (DU) have been extensively proposed. Thus, we have designed and fabricated two identical small-scale getter beds for a comparison of ZrCo with DU on the hydriding/dehydriding properties. After the powderization of the metals, the hydriding/dehydriding performance at different stoichiometries of ZrCo and DU was measured. We provide preliminary experimental results of our ZrCo and DU beds.

  12. Titanium compacts produced by the pulvimetallurgical hydride-dehydride method for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Barreiro, M M [Materiales Dentales, Facultad de OdontologIa, Universidad de Buenos Aires, Marcelo T de Alvear 2142 (1122), Buenos Aires (Argentina); Grana, D R; Kokubu, G A [PatologIa I. Escuela de OdontologIa, Facultad de Medicina. Asociacion Odontologica Argentina-Universidad del Salvador, Tucuman 1845 (1050) Buenos Aires (Argentina); Luppo, M I; Mintzer, S; Vigna, G, E-mail: mbarreiro@mater.odon.uba.a, E-mail: dgrana@usal.edu.a, E-mail: luppo@cnea.gov.a, E-mail: vigna@cnea.gov.a [Departamento Materiales, Comision Nacional de Energia Atomica, Gral Paz 1499 (B1650KNA), San MartIn, Buenos Aires (Argentina)

    2010-04-15

    Titanium powder production by the hydride-dehydride method has been developed as a non-expensive process. In this work, commercially pure grade two Ti specimens were hydrogenated. The hydrided material was milled in a planetary mill. The hydrided titanium powder was dehydrided and then sieved to obtain a particle size between 37 and 125{mu}m in order to compare it with a commercial powder produced by chemical reduction with a particle size lower than 150{mu}m. Cylindrical green compacts were obtained by uniaxial pressing of the powders at 343 MPa and sintering in vacuum. The powders and the density of sintered compacts were characterized, the oxygen content was measured and in vivo tests were performed in the tibia bones of Wistar rats in order to evaluate their biocompatibility. No differences were observed between the materials which were produced either with powders obtained by the hydride-dehydride method or with commercial powders produced by chemical reduction regarding modifications in compactation, sintering and biological behaviour.

  13. Titanium compacts produced by the pulvimetallurgical hydride-dehydride method for biomedical applications

    International Nuclear Information System (INIS)

    Barreiro, M M; Grana, D R; Kokubu, G A; Luppo, M I; Mintzer, S; Vigna, G

    2010-01-01

    Titanium powder production by the hydride-dehydride method has been developed as a non-expensive process. In this work, commercially pure grade two Ti specimens were hydrogenated. The hydrided material was milled in a planetary mill. The hydrided titanium powder was dehydrided and then sieved to obtain a particle size between 37 and 125 μm in order to compare it with a commercial powder produced by chemical reduction with a particle size lower than 150 μm. Cylindrical green compacts were obtained by uniaxial pressing of the powders at 343 MPa and sintering in vacuum. The powders and the density of sintered compacts were characterized, the oxygen content was measured and in vivo tests were performed in the tibia bones of Wistar rats in order to evaluate their biocompatibility. No differences were observed between the materials which were produced either with powders obtained by the hydride-dehydride method or with commercial powders produced by chemical reduction regarding modifications in compactation, sintering and biological behaviour.

  14. Dehydriding and rehydriding properties of Mg(NH2)2-LiH systems

    International Nuclear Information System (INIS)

    Aoki, M.; Noritake, T.; Nakamori, Y.; Towata, S.; Orimo, S.

    2007-01-01

    The dehydriding and rehydriding properties of the mixtures of 3Mg(NH 2 ) 2 + nLiH (n = 6, 8, and 12) were investigated by pressure-composition (p-c) isotherm and X-ray diffraction (XRD) measurements in order to clarify the effects of the LiH ratio n on the properties. The amounts of the hydrogen desorbed from the mixtures with n = 6, 8, and 12 were 5.4, 5.1, and 4.5 mass%, respectively; this indicates that the amounts on a unit mass basis decrease with increasing n. However, the molar ratios of the desorbed hydrogen to the mixtures estimated from the amounts were almost equal, and also the features of the p-c isotherms were similar to each other. Moreover, the Li 2 Mg(NH) 2 and LiH phases were observed in XRD profiles of all the mixtures after p-c isotherm measurements. These results suggest that the dehydriding reaction of the mixtures of 3Mg(NH 2 ) 2 + nLiH (n = 6, 8, and 12) under hydrogen pressure is not dominantly affected by the value of n. On the other hand, the amounts of the ammonia desorbed from the mixtures detected by mass spectroscopy decreased with increasing n

  15. The Improvement of Dehydriding the Kinetics of NaMgH3 Hydride via Doping with Carbon Nanomaterials

    Directory of Open Access Journals (Sweden)

    Zhong-Min Wang

    2016-12-01

    Full Text Available NaMgH3 perovskite hydride and NaMgH3–carbon nanomaterials (NH-CM composites were prepared via the reactive ball-milling method. To investigate the catalytic effect of CM on the dehydriding kinetic properties of NaMgH3 hydride, multiwall carbon nanotubes (MWCNTs and graphene oxide (GO were used as catalytic additives. It was found that dehydriding temperatures and activation energies (ΔE1 and ΔE2 for two dehydrogenation steps of NaMgH3 hydride can be greatly reduced with a 5 wt. % CM addition. The NH–2.5M–2.5G composite presents better dehydriding kinetics, a lower dehydriding temperature, and a higher hydrogen-desorbed amount (3.64 wt. %, 638 K. ΔE1 and ΔE2 can be reduced by about 67 kJ/mol and 30 kJ/mol, respectively. The results suggest that the combination of MWCNTs and GO is a better catalyst as compared to MWCNTs or GO alone.

  16. Dehydriding reaction of Mg(NH2)2-LiH system under hydrogen pressure

    International Nuclear Information System (INIS)

    Aoki, M.; Noritake, T.; Kitahara, G.; Nakamori, Y.; Towata, S.; Orimo, S.

    2007-01-01

    The dehydriding and structural properties of the 3Mg(NH 2 ) 2 + 12LiH system under hydrogen pressure were investigated using the pressure-composition (p-c) isotherm measurement and X-ray diffraction (XRD) analysis. Two distinct regions, a plateau region and a sloping region, can be seen on the p-c isotherms and the amount of the desorbed hydrogen at 523 K was 4.9 mass%. The enthalpy of hydrogenation calculated using a van't Hoff plot was -46 kJ/mol H 2 . The dehydriding reaction was proposed for the 3Mg(NH 2 ) 2 + 12LiH system based on the obtained p-c isotherms and XRD profiles and chemical valences of Li, Mg, N, and H. In the plateau region on the p-c isotherm, Mg(NH 2 ) 2 , Li 4 Mg 3 (NH 2 ) 2 (NH) 4 (tetragonal), and LiH phases coexist and the molar ratio of the Li 4 Mg 3 (NH 2 ) 2 (NH) 4 phase increases (while those of Mg(NH 2 ) 2 and LiH phases decrease) with the amount of the desorbed hydrogen. On the other hand, the mixture of Li 4+x Mg 3 (NH 2 ) 2-x (NH) 4+x + (8-x)LiH (0 ≤ x ≤ 2) is formed and the lattice volume of the Li 4+x Mg 3 (NH 2 ) 2-x (NH) 4+x phase continuously increases with the amount of the desorbed hydrogen in the sloping region on the p-c isotherm

  17. Low-Pressure and Low-Temperature Hydriding-Pulverization-Dehydriding Method for Producing Shape Memory Alloy Powders

    Science.gov (United States)

    Murguia, Silvia Briseño; Clauser, Arielle; Dunn, Heather; Fisher, Wendy; Snir, Yoav; Brennan, Raymond E.; Young, Marcus L.

    2018-04-01

    Shape memory alloys (SMAs) are of high interest as active, adaptive "smart" materials for applications such as sensors and actuators due to their unique properties, including the shape memory effect and pseudoelasticity. Binary NiTi SMAs have shown the most desirable properties, and consequently have generated the most commercial success. A major challenge for SMAs, in particular, is their well-known compositional sensitivity. Therefore, it is critical to control the powder composition and morphology. In this study, a low-pressure, low-temperature hydriding-pulverization-dehydriding method for preparing well-controlled compositions, size, and size distributions of SMA powders from wires is presented. Starting with three different diameters of as-drawn martensitic NiTi SMA wires, pre-alloyed NiTi powders of various well-controlled sizes are produced by hydrogen charging the wires in a heated H3PO4 solution. After hydrogen charging for different charging times, the wires are pulverized and subsequently dehydrided. The wires and the resulting powders are characterized using scanning electron microscopy, differential scanning calorimetry, and X-ray diffraction. The relationship between the wire diameter and powder size is investigated as a function of hydrogen charging time. The rate of diameter reduction after hydrogen charging of wire is also examined. Finally, the recovery behavior due to the shape memory effect is investigated after dehydriding.

  18. Dehydriding Process and Hydrogen–Deuterium Exchange of LiBH4–Mg2FeD6 Composites

    Directory of Open Access Journals (Sweden)

    Guanqiao Li

    2015-06-01

    Full Text Available The dehydriding process and hydrogen–deuterium exchange (H–D exchange of xLiBH4 + (1 − xMg2FeD6 (x = 0.25, 0.75 composites has been studied in detail. For the composition with x = 0.25, only one overlapping mass peak of all hydrogen and deuterium related species was observed in mass spectrometry. This implied the simultaneous dehydriding of LiBH4 and Mg2FeD6, despite an almost 190 °C difference in the dehydriding temperatures of the respective discrete complex hydrides. In situ infrared spectroscopy measurements indicated that H–D exchange between [BH4]− and [FeD6]4− had occurred during ball-milling and was promoted upon heating. The extent of H–D exchange was estimated from the areas of the relevant mass signals: immediately prior to the dehydriding, more than two H atoms in [BH4]− was replaced by D atoms. For x = 0.75, H–D exchange also occurred and about one to two H atoms in [BH4]− was replaced by D atoms immediately before the dehydriding. In contrast to the situation for x = 0.25, firstly LiBH4 and Mg2FeD6 dehydrided simultaneously with a special molar ratio = 1:1 at x = 0.75, and then the remaining LiBH4 reacted with the Mg and Fe derived from the dehydriding of Mg2FeD6.

  19. Effect of amorphous Mg50Ni50 on hydriding and dehydriding behavior of Mg2Ni alloy

    International Nuclear Information System (INIS)

    Guzman, D.; Ordonez, S.; Fernandez, J.F.; Sanchez, C.; Serafini, D.; Rojas, P.A.; Aguilar, C.; Tapia, P.

    2011-01-01

    Composite Mg 2 Ni (25 wt.%) amorphous Mg 50 Ni 50 was prepared by mechanical milling starting with nanocrystalline Mg 2 Ni and amorphous Mg 50 Ni 50 powders, by using a SPEX 8000 D mill. The morphological and microstructural characterization of the powders was performed via scanning electron microscopy and X-ray diffraction. The hydriding characterization of the composite was performed via a solid gas reaction method in a Sievert's-type apparatus at 363 K under an initial hydrogen pressure of 2 MPa. The dehydriding behavior was studied by differential thermogravimetry. On the basis of the results, it is possible to conclude that amorphous Mg 50 Ni 50 improved the hydriding and dehydriding kinetics of Mg 2 Ni alloy upon cycling. A tentative rationalization of experimental observations is proposed. - Research Highlights: → First study of the hydriding behavior of composite Mg 2 Ni (25 wt.%) amorphous Mg 50 Ni 50 . → Microstructural characterization of composite material using XRD and SEM was obtained. → An improved effect of Mg 50 Ni 50 on the Mg 2 Ni hydriding behavior was verified. → The apparent activation energy for the hydrogen desorption of composite was obtained.

  20. Hydriding and dehydriding rates of Mg, Mg-10TaF5, and Mg-10NbF5 prepared via reactive mechanical grinding

    Science.gov (United States)

    Song, Myoung Youp; Kwak, Young Jun; Lee, Seong Ho; Park, Hye Ryoung

    2015-01-01

    In this work, TaF5 and NbF5 were chosen as additives to enhance the hydriding and dehydriding rates of Mg. Mg, Mg-10TaF5, and Mg-10NbF5 samples were prepared by reactive mechanical grinding. The hydriding and dehydriding properties of the samples were then examined. Mg-10TaF5 had the largest amount of hydrogen absorbed for 30 min and the highest initial dehydriding rate after incubation period, followed in order by Mg-10NbF5, and Mg. At 593 K under 12 bar H2 at the first cycle, Mg-10TaF5 absorbed 3.63 wt% H for 5 min and 4.53 wt% H for 30 min. At 593 K under 1.0 bar H2 at the first cycle, Mg-10TaF5 desorbed 0 wt% H for 2.5 min, 0.59 wt% H for 5 min, 3.42 wt% H for 30 min, and 4.24 wt% H for 60 min. The reactive mechanical grinding of Mg with TaF5 or NbF5 is believed to have facilitated the nucleation and to have decreased the diffusion distances of hydrogen atoms. These two effects are believed to have increased the hydriding and dehydriding rates of Mg. The MgF2 and Ta2H formed in Mg-10TaF5, and the MgF2, NbH2, and NbF3 formed in Mg-10NbF5 are considered to have enhanced both of these effects.

  1. Improved dehydriding property of polyvinylpyrrolidone coated Mg-Ni hydrogen storage nano-composite prepared by hydriding combustion synthesis and wet mechanical milling

    Directory of Open Access Journals (Sweden)

    Linglong Yao

    2018-02-01

    Full Text Available In this work, polyvinylpyrrolidone (PVP coated Mg95Ni5 nano-composites were prepared by hydriding combustion synthesis (HCS plus wet mechanical milling (WM with tetrahydrofuran (THF and donated as WM-x wt% PVP (x = 1, 3, 5 and 7 respectively. The phase compositions, microstructures and dehydriding property, as well as the co-effect of PVP and THF were investigated in detail. XRD results showed that the average crystal size of MgH2 in the milled Mg95Ni5 decreased from 23 nm without PVP to 18 nm with 1 wt% PVP. The peak temperature of dehydrogenation of MgH2 in the milled Mg95Ni5 decreased from 293.0 °C without THF to 250.4 °C with THF. The apparent activation energy for decomposition of MgH2 in WM-7 wt% PVP was estimated to be 66.94 kJ/mol, which is 37.70 kJ/mol lower than that of milled Mg95Ni5 without THF and PVP. PVP and THF can facilitate the refinement of particle size during mechanical milling process. Attributed to small particle sizes and synergistic effect of PVP and THF, the composites exhibit markedly improved dehydriding properties. Keywords: Mg-Ni-PVP, Composite, Mg-based alloy, Wet mechanical milling, Dehydriding temperature

  2. Dehydriding and re-hydriding properties of high-energy ball milled LiBH{sub 4}+MgH{sub 2} mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Crosby, Kyle; Shaw, Leon L. [Department of Chemical, Materials and Biomolecular Engineering, University of Connecticut, 97 North Eagleville Road, U-3136, Storrs, CT 06269 (United States)

    2010-07-15

    Here we report the first investigation of the dehydriding and re-hydriding properties of 2LiBH{sub 4} + MgH{sub 2} mixtures in the solid state. Such a study is made possible by high-energy ball milling of 2LiBH{sub 4}+MgH{sub 2} mixtures at liquid nitrogen temperature with the addition of graphite. The 2LiBH{sub 4}+MgH{sub 2} mixture ball milled under this condition exhibits a 5-fold increase in the released hydrogen at 265 C when compared with ineffectively ball milled counterparts. Furthermore, both LiBH{sub 4} and MgH{sub 2} contribute to hydrogen release in the solid state. The isothermal dehydriding/re-hydriding cycles at 265 C reveal that re-hydriding is dominated by re-hydriding of Mg. These unusual phenomena are explained based on the formation of nanocrystalline and amorphous phases, the increased defect concentration in crystalline compounds, and possible catalytic effects of Mg,MgH{sub 2} and LiBH{sub 4} on their dehydriding and re-hydriding properties. (author)

  3. Process variables in the obtention of U-Mo powder by the hydriding-milling-dehydriding method (HMD process)

    International Nuclear Information System (INIS)

    Pasqualini, Enrique E.; Helzel Garcia, Javier; Lopez, Marisol

    2003-01-01

    In the next few years nuclear fuels based on uranium oxides, aluminides and silicides for MTR reactors will be replaced by the high density alloy uranium- 7% (w/w) molybdenum (U-7 Mo). Actually there is only one commercial supplier of this raw material that has to be provided as powder containing 20% enriched uranium ( 235 U). In the Nuclear Fuels Department of the National Atomic Energy Commission (CNEA) at Buenos Aires was developed an alternative way of producing U-7 Mo powder in a production scale. Meanwhile CNEA is participating in the International Program (RERTR) for final qualification of this nuclear material. This new method of production consists in the hydriding of the alloy, milling the hydride to final size and dehydriding the powder. These results were achieved because a special technique was discovered for the massive hydriding of the U-7 Mo alloy. The production method is simple, requires conventional equipment and low investment. Argentine can have important comparative advantages for its production and exportation. A scale production plant is being planed. (author)

  4. Improved design model for the multi-bed system in the storage and delivery system at ITER: Effects of decay of hydriding and dehydriding rate of a getter bed

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jae-Uk [Department of Chemical Engineering, Pohang University of Science and Technology, San 31, Hyoja-Dong, Pohang 790-784 (Korea, Republic of); Chang, Min Ho; Yun, Sei-Hun [National Fusion Research Institute, 169-148-gil Kwahak-ro, Yusong-gu, Daejon 34133 (Korea, Republic of); Lee, Euy Soo, E-mail: eslee@dongguk.edu [Department of Chemical & Biochemical Engineering, Dongguk University, Seoul 100-715 (Korea, Republic of); Lee, In-Beum [Department of Chemical Engineering, Pohang University of Science and Technology, San 31, Hyoja-Dong, Pohang 790-784 (Korea, Republic of)

    2016-12-15

    This paper proposes an improved design model for the multi-bed system in the Storage and Delivery System considering that the hydriding and dehydriding rates of a getter bed decay over time. More specifically, the hydriding and dehydriding rates are influenced by the amount of remaining inventory in the getter bed and time simultaneously. Therefore, we formulate the rate decays mathematically to consider these features in the design model. The optimization problem is formulated as a mixed integer nonlinear program (MINLP) model with nonlinear constraints. Inductive operation scenario is presented to illustrate the applicability of the proposed model.

  5. Improved design model for the multi-bed system in the storage and delivery system at ITER: Effects of decay of hydriding and dehydriding rate of a getter bed

    International Nuclear Information System (INIS)

    Lee, Jae-Uk; Chang, Min Ho; Yun, Sei-Hun; Lee, Euy Soo; Lee, In-Beum

    2016-01-01

    This paper proposes an improved design model for the multi-bed system in the Storage and Delivery System considering that the hydriding and dehydriding rates of a getter bed decay over time. More specifically, the hydriding and dehydriding rates are influenced by the amount of remaining inventory in the getter bed and time simultaneously. Therefore, we formulate the rate decays mathematically to consider these features in the design model. The optimization problem is formulated as a mixed integer nonlinear program (MINLP) model with nonlinear constraints. Inductive operation scenario is presented to illustrate the applicability of the proposed model.

  6. Effect of amorphous Mg{sub 50}Ni{sub 50} on hydriding and dehydriding behavior of Mg{sub 2}Ni alloy

    Energy Technology Data Exchange (ETDEWEB)

    Guzman, D., E-mail: danny.guzman@uda.cl [Departamento de Ingenieria en Metalurgia, Facultad de Ingenieria, Universidad de Atacama y Centro Regional de Investigacion y Desarrollo Sustentable de Atacama (CRIDESAT), Av. Copayapu 485, Copiapo (Chile); Ordonez, S. [Departamento de Ingenieria Metalurgica, Facultad de Ingenieria, Universidad de Santiago de Chile, Av. Lib. Bernardo O' Higgins 3363, Santiago (Chile); Fernandez, J.F.; Sanchez, C. [Departamento de Fisica de Materiales, Facultad de Ciencias, Universidad Autonoma de Madrid, Cantoblanco 28049, Madrid (Spain); Serafini, D. [Departamento de Fisica, Facultad de Ciencias, Universidad de Santiago de Chile and Center for Interdisciplinary Research in Materials, CIMAT, Av. Lib. Bernardo O' Higgins 3363, Santiago (Chile); Rojas, P.A. [Escuela de Ingenieria Mecanica, Facultad de Ingenieria, Av. Los Carrera 01567, Quilpue, Pontificia Universidad Catolica de Valparaiso, PUCV (Chile); Aguilar, C. [Departamento de Ingenieria Metalurgica y Materiales, Universidad Tecnica Federico Santa Maria, Av. Espana 1680, Valparaiso (Chile); Tapia, P. [Departamento de Ingenieria en Metalurgia, Facultad de Ingenieria, Universidad de Atacama, Av. Copayapu 485, Copiapo (Chile)

    2011-04-15

    Composite Mg{sub 2}Ni (25 wt.%) amorphous Mg{sub 50}Ni{sub 50} was prepared by mechanical milling starting with nanocrystalline Mg{sub 2}Ni and amorphous Mg{sub 50}Ni{sub 50} powders, by using a SPEX 8000 D mill. The morphological and microstructural characterization of the powders was performed via scanning electron microscopy and X-ray diffraction. The hydriding characterization of the composite was performed via a solid gas reaction method in a Sievert's-type apparatus at 363 K under an initial hydrogen pressure of 2 MPa. The dehydriding behavior was studied by differential thermogravimetry. On the basis of the results, it is possible to conclude that amorphous Mg{sub 50}Ni{sub 50} improved the hydriding and dehydriding kinetics of Mg{sub 2}Ni alloy upon cycling. A tentative rationalization of experimental observations is proposed. - Research Highlights: {yields} First study of the hydriding behavior of composite Mg{sub 2}Ni (25 wt.%) amorphous Mg{sub 50}Ni{sub 50}. {yields} Microstructural characterization of composite material using XRD and SEM was obtained. {yields} An improved effect of Mg{sub 50}Ni{sub 50} on the Mg{sub 2}Ni hydriding behavior was verified. {yields} The apparent activation energy for the hydrogen desorption of composite was obtained.

  7. PENGARUH SERBUK U-Mo HASIL PROSES MEKANIK DAN HYDRIDE – DEHYDRIDE – GRINDING MILL TERHADAP KUALITAS PELAT ELEMEN BAKAR U-Mo/Al

    Directory of Open Access Journals (Sweden)

    Supardjo Supardjo

    2015-07-01

    Full Text Available PENGARUH SERBUK U-Mo HASIL PROSES MEKANIK DAN HYDRIDE – DEHYDRIDE – GRINDING MILL TERHADAP KUALITAS PELAT ELEMEN BAKAR U-Mo/Al. Penelitian bahan bakar U-7Mo/Al tipe pelat dilakukan dalam rangka pengembangan bahan bakar U3Si2/Al untuk mendapatkan bahan bakar baru yang memiliki densitas uranium lebih tinggi, stabil selama digunakan sebagai bahan bakar di dalam reaktor dan mudah dilakukan proses olah ulangnya. Lingkup penelitian meliputi pembuatan: paduan U-7Mo dengan teknik peleburan, pembuatan serbuk U-7Mo dengan dikikir dan hydride - dehydride - grinding mill, IEB U-7Mo/Al dengan teknik kompaksi pada tekanan 20 bar, dan PEB U-7Mo/Al dengan teknik pengerolan panas pada temperatur 425oC. Paduan U-7Mo hasil proses peleburan cukup homogen, berat jenis 16,34 g/cm3 dan bersifat ulet, kemudian dibuat menjadi serbuk dengan cara dikikir dan hydride - dehydride - grinding mill. Serbuk U-7Mo hasil proses kikir berbentuk pipih, kontaminan Fe cukup tinggi, sedangkan serbuk hasil proses hydride - dehydride - grinding mill, cenderung equiaxial dengan kontaminan yang rendah. Kedua jenis serbuk U-7Mo tersebut digunakan sebagai bahan baku pembuatan IEB U-7Mo/Al dan PEB U-7Mo/Al dengan densitas uranium 7 gU/cm3 dan diperoleh produk dengan kualitas yang hampir sama. Hasil uji IEB U-7Mo/Al berukuran 25 x 15 x 3,15±0,05 mm, tidak terdapat cacat/retak, distribusi U-7Mo di dalam matriks cukup homogen dan tidak terdapat pengelompokan/aglomerasi U-7Mo yang berdimensi >1 mm. PEB U-7Mo/Al hasil pengerolan dengan tebal akhir 1,45 mm, memiliki ketebalan meat rerata 0,60 mm dan tebal kelongsong 0,4 mm dan terdapat 1 titik pengukuran kelongsong dengan ketebalan 0,15 mm. Dengan membandingkan penggunaan kedua jenis serbuk U-7Mo tersebut, IEB U-7Mo/Al dan PEB U-7Mo/Al yang dihasilkan memiliki kualitas hampir sama. Namun demikian penggunaan serbuk U- 7Mo hasil proses hydride - dehydride - grinding mill lebih baik karena proses pengerjaannya lebih cepat dan impuritas dalam

  8. Comminution by hydriding-dehydriding process of the U-Zr-Nb alloys stabilized at different phases by aging heat treatment

    Energy Technology Data Exchange (ETDEWEB)

    Cantagalli, Natalia Mattar; Pais, Rafael Witter Dias; Braga, Daniel Martins; Santos, Ana Maria Matildes dos; Ferraz, Wilmar Barbosa, E-mail: ferrazw@cdtn.b [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG) Belo Horizonte, MG (Brazil)

    2011-07-01

    Powders of the U-Zr-Nb alloys are raw materials for obtaining plate-type dispersion fuel of high density and medium enrichment for research and test reactors as well as small power reactors. U-2.5Zr-7.5Nb and U-3Zr-9Nb (wt%) alloys, initially homogenized at high temperatures, were transformed at different phases by means aging heat treatments, and then comminuted by hydriding-dehydriding process to powder production. The phases transformations were obtained by the homogenization of the U-2.5Zr-7.5Nb and U-3Zr-9Nb alloys at high temperatures (1000 deg C for 1 and 16 h), followed by aging heat treatment at 600 deg C, in times of 0.5 h, 3.0 h and 24h, and subsequently quenched in water to stabilize the desired phase. The comminution process was performed at 200 deg C for different times ranging from 20 minutes to 4 hours. The powders were then characterized by scanning electron microscopy, X-ray diffraction and determination of particle size distribution by means of laser equipment CILAS. One of the main objectives of this study was to verify the influence of the different phases in the characteristics of the obtained powders. It was found that alloys stabilized in gamma phase produced powders with smaller particles sizes than those with cellular structure of the {alpha} and {gamma} phases. Regardless of retained phases, the produced powders consist of agglomerates with irregular morphology. (author)

  9. Comminution by hydriding-dehydriding process of the U-Zr-Nb alloys stabilized at different phases by aging heat treatment

    International Nuclear Information System (INIS)

    Cantagalli, Natalia Mattar; Pais, Rafael Witter Dias; Braga, Daniel Martins; Santos, Ana Maria Matildes dos; Ferraz, Wilmar Barbosa

    2011-01-01

    Powders of the U-Zr-Nb alloys are raw materials for obtaining plate-type dispersion fuel of high density and medium enrichment for research and test reactors as well as small power reactors. U-2.5Zr-7.5Nb and U-3Zr-9Nb (wt%) alloys, initially homogenized at high temperatures, were transformed at different phases by means aging heat treatments, and then comminuted by hydriding-dehydriding process to powder production. The phases transformations were obtained by the homogenization of the U-2.5Zr-7.5Nb and U-3Zr-9Nb alloys at high temperatures (1000 deg C for 1 and 16 h), followed by aging heat treatment at 600 deg C, in times of 0.5 h, 3.0 h and 24h, and subsequently quenched in water to stabilize the desired phase. The comminution process was performed at 200 deg C for different times ranging from 20 minutes to 4 hours. The powders were then characterized by scanning electron microscopy, X-ray diffraction and determination of particle size distribution by means of laser equipment CILAS. One of the main objectives of this study was to verify the influence of the different phases in the characteristics of the obtained powders. It was found that alloys stabilized in gamma phase produced powders with smaller particles sizes than those with cellular structure of the α and γ phases. Regardless of retained phases, the produced powders consist of agglomerates with irregular morphology. (author)

  10. How to Analyse Metal Hydride Decomposition Temperatures Using a Sieverts’ Type Hydriding-Dehydriding Apparatus and Hydrogen-Storage Characteristics for an MgH2–Based Alloy

    Directory of Open Access Journals (Sweden)

    Young Jun KWAK

    2018-02-01

    Full Text Available In this work, a method to analyze metal hydride decomposition temperatures (the onset temperature of the metal hydride decomposition and the temperature for the maximum ratio of released gas quantity change with temperature change, of prepared samples were investigated using a Sieverts’ type hydriding-dehydriding apparatus, in which a back-pressure regulator was employed. The quantity of the gas released under 1.0 bar H2 was measured as the temperature was increased with a heating rate of 4 K/min. The variation in the ratio of released hydrogen quantity Hd change with temperature T change, dHd/dT, as a function of temperature was obtained and from the variation in dHd/dT with T, the metal hydride decomposition temperatures were analyzed. This analysis method can be used instead of thermal analysis methods such as thermogravimetric analysis (TGA, differential scanning calorimetry (DSC analysis, differential thermal analysis (DTA, and thermal desorption spectroscopy (TDS analysis. For this analysis, a sample with a composition of 89 wt.% MgH2 + 4.9 wt.% Ni + 1.7 wt.% Zn(BH42 + 1.0 wt% NaCl + 1.7 wt.% Ti + 1.7 wt % Fe (named MgH2-Ni-Zn(BH42-NaCl-Ti-Fe sample was prepared by planetary ball milling. In the prepared MgH2-Ni-Zn(BH42-NaCl-Ti-Fe sample, it is believed that MgH2 begins to decompose at about 575 K and dHd/dT reaches its peak at about 610 K.DOI: http://dx.doi.org/10.5755/j01.ms.24.1.17664

  11. Hydriding and dehydriding rates and hydrogen-storage capacity of ...

    Indian Academy of Sciences (India)

    means of nuclear, wind, solar, tidal or geothermal energy. When hydrogen is converted into energy, water is the only exhaust product. It is thus extremely environmental friendly as an energy carrier. Although hydrogen has obvious benefits, an immediate incorporation of hydrogen into the world economy has a number of ...

  12. Changes in phase composition of Zr-Fe-V getter after hydriding and vacuum dehydriding cycles

    Czech Academy of Sciences Publication Activity Database

    Roupcová, Pavla; Schneeweiss, Oldřich

    2010-01-01

    Roč. 492, č. 1-2 (2010), s. 160-165 ISSN 0925-8388 R&D Projects: GA MŠk 1M0512; GA ČR GP106/09/P556 Institutional research plan: CEZ:AV0Z20410507 Keywords : Hydrogen storage materials * Non-evaporable getter * X-ray diffraction * Mössbauer spectroscopy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.138, year: 2010

  13. Improving solid-state hydriding and dehydriding properties of the LiBH{sub 4} plus MgH{sub 2} system with the addition of Mn and V dopants

    Energy Technology Data Exchange (ETDEWEB)

    Crosby, Kyle; Wan, Xuefei; Shaw, Leon L. [Department of Chemical, Materials and Biomolecular Engineering, University of Connecticut, 97 North Eagleville Road, U-3136, Storrs, CT 06269 (United States)

    2010-11-01

    The hydriding process of the 2LiH + MgB{sub 2} mixture is controlled by outward diffusion of Mg and inward diffusion of Li and H within MgB{sub 2} crystals to form LiBH{sub 4}. This study explores the feasibility of using transition metal dopants, such as Mn and V, to enhance the diffusion rate and thus the hydriding kinetics. It is found that Mn can indeed enhance the hydriding kinetics of the 2LiH + MgB{sub 2} mixture, while V does not. The major factor in enhancing the diffusion rate and thus the hydriding kinetics is related to the dopant's ability to induce the lattice distortion of MgB{sub 2} crystals. This study demonstrates that the kinetics of the diffusion controlled solid-state hydriding process can be improved by doping if the dopant is properly selected. (author)

  14. Preparation of uranium nitride

    International Nuclear Information System (INIS)

    Potter, R.A.; Tennery, V.J.

    1976-01-01

    A process is described for preparing actinide-nitrides from massive actinide metal which is suitable for sintering into low density fuel shapes by partially hydriding the massive metal and simultaneously dehydriding and nitriding the dehydrided portion. The process is repeated until all of the massive metal is converted to a nitride

  15. Comparison of hydrogen storage properties of pure Mg and milled ...

    Indian Academy of Sciences (India)

    Administrator

    increase the hydriding and dehydriding rates, pure Mg was ground under hydrogen atmosphere (reactive .... Hydrogen storage properties of pure Mg and milled pure Mg. 833. Figure 3. ... elongated and flat shapes via collisions with the steel.

  16. Vacuum hot pressing of titanium-alloy powders

    International Nuclear Information System (INIS)

    Malik, R.K.

    1975-01-01

    Full or nearly full dense products of wrought-metal properties have been obtained by vacuum hot pressing (VHP) of several prealloyed Ti--6Al--4V powders including hydride, hydride/dehydride, and rotating electrode process (REP) spherical powder. The properties of billets VHP from Ti--6Al--4V hydride powder and from hydride/dehydride powders have been shown to be equivalent. The REP spherical powder billets processed by VHP or by hot isostatic pressing (HIP) resulted in equivalent tensile properties. The potential of VHP for fabrication of near net aircraft parts such as complex fittings and engine disks offers considerable cost savings due to reduced material and machining requirements

  17. CO impurities effect on LaNi 4.7 Al 0.3 hydrogen storage alloy ...

    Indian Academy of Sciences (India)

    temperature test. The activated sample was completely deactivated after only 3 hydriding/dehydriding cycles in hydrogen containing 300 ppm CO at 30 °C, but hydrogen storage capacity did not degrade when tested at 80 °C. Additionally, two ...

  18. In-situ X-ray diffraction : a useful tool to investigate hydride-formation reactions

    NARCIS (Netherlands)

    Notten, P.H.L.; Daams, J.L.C.; Veirman, de A.E.M.; Staals, A.A.

    1994-01-01

    A high-pressure X-ray diffraction (XRD) cell has been designed which allowed us to study simultaneously hydrogen absorption/desorption isotherms and XRD powder diffraction patterns on (de)hydrided intermetallic compounds. The hydride formation reaction was investigated in the case of LaNi5 under

  19. Neutron scattering study of the phase transformation of LaNi3 induced by hydriding

    International Nuclear Information System (INIS)

    Ruan Jinghui; Zeng Xiangxin; Niu Shiwen

    1994-01-01

    The phase transformation of LaNi 3 induced by hydriding and de-hydriding is investigated using the neutron diffraction and the neutron inelastic scattering. The results show that the hydriding sample, LaNi 3 H x , is transformed from crystalline state of the LaNi 3 into amorphous state with a microcrystalline characteristic of LaNi 5 , and the de-hydriding sample produced by LaNi 3 H x dehydrated at 600 degree C is decomposed into new crystalline states composed by LaNi 5 -and La-hydrides. The procedure of phase transformation is that the result of the transformation of LaNi 3 induced by hydriding shows the properties of LaNi 5 -H 2 system

  20. Scaling up the production capacity of U-Mo powder by HMD process

    International Nuclear Information System (INIS)

    Pasqualini, E.E.; Lopez, M.; Helzel Garcia, L.J.; Echenique, P.; Adelfang, P.

    2002-01-01

    The recent discovery that uranium alloys in metastable gamma phase can be hydrided at low temperatures and pressures have allowed developing the method of commuting bulk materials by milling the hydride to desired size and then dehydriding the powder. This process is called HMD (hydriding-milling-dehydriding) and needs an initial step of hydrogen incorporation to allow the alloy to be hydrided. This four step process has been conveniently set up for the production of U-7Mo powder for its use in nuclear fuels. Low equipment investment and low man power are needed for this achievement. The process is being analyzed in its scaling up for one kilogram batches and a 50 kilogram per year production capacity of U-Mo powder. (author)

  1. Microstructure and hydrogen sorption kinetics of Mg nanopowders with catalyst

    International Nuclear Information System (INIS)

    Revesz, A.; Fatay, D.; Spassov, T.

    2007-01-01

    MgH 2 powders were ball-milled with and without catalysts (Nb 2 O 5 ) under hydrogen in a high-energy mill for 10 h. Morphological, structural and microstructural characterization of the nanocomposites, including particle and crystallite size distribution were carried out before and after hydrogen absorption. In order to study the above-mentioned microstructural parameters imaging and X-ray scattering techniques (high-resolution X-ray diffractometry) have been employed. The effect of the particle and grain size on the hydriding/dehydriding kinetics of ball-milled MgH 2 + catalyst powders was analyzed. The grain and particle size reduction enhances substantially the hydriding/dehydriding

  2. Investigation of powdering ductile gamma U-10 wt%Mo alloy for dispersion fuels

    Energy Technology Data Exchange (ETDEWEB)

    Leal Neto, R.M., E-mail: lealneto@ipen.br [Nuclear and Energy Research Institute, IPEN/CNEN-SP, São Paulo (Brazil); Rocha, C.J. [Nuclear and Energy Research Institute, IPEN/CNEN-SP, São Paulo (Brazil); Urano de Carvalho, E. [Nuclear and Energy Research Institute, IPEN/CNEN-SP, São Paulo (Brazil); Science and Technology Brazilian Institute, Innovating Nuclear Reactors (Brazil); Riella, H.G. [Science and Technology Brazilian Institute, Innovating Nuclear Reactors (Brazil); Chemical Engineering Department, Santa Catarina Federal University, Florianópolis (Brazil); Durazzo, M. [Nuclear and Energy Research Institute, IPEN/CNEN-SP, São Paulo (Brazil); Science and Technology Brazilian Institute, Innovating Nuclear Reactors (Brazil)

    2014-02-01

    This work forms part of the studies presently ongoing at Nuclear and Energy Research Institute – IPEN/CNEN-SP investigating the feasibility of powdering ductile U-10 wt%Mo alloy by hydriding–milling–dehydriding of the gamma phase (HMD). Hydriding was conducted at room temperature in a Sievert apparatus following heat treatment activation. Hydrided pieces were fragile enough to be hand milled to the desired particle size range. Hydrogen was removed by heating the samples under high vacuum. X-ray diffraction analysis of the hydrided material showed an amorphous-like pattern that is completely reversed following dehydriding. The hydrogen content of the hydrided samples corresponds to a trihydride, i.e. (U,Mo)H{sub 3}. SEM analysis of HMD powder particles revealed equiaxial powder particles together with some plate-like particles. A hypothesis for the amorphous hydride phase formation is suggested.

  3. Experience in handling concentrated tritium

    International Nuclear Information System (INIS)

    Holtslander, W.J.

    1985-12-01

    The notes describe the experience in handling concentrated tritium in the hydrogen form accumulated in the Chalk River Nuclear Laboratories Tritium Laboratory. The techniques of box operation, pumping systems, hydriding and dehydriding operations, and analysis of tritium are discussed. Information on the Chalk River Tritium Extraction Plant is included as a collection of reprints of papers presented at the Dayton Meeting on Tritium Technology, 1985 April 30 - May 2

  4. Improvement of the Reaction Rates of Mg with H{sub 2} by the Addition of TaF{sub 5} via Reactive Mechanical Grinding

    Energy Technology Data Exchange (ETDEWEB)

    Song, Myoung Youp [Chonbuk National University, Jeonju (Korea, Republic of); Kwak, Young Jun; Lee, Seong Ho [Chonbuk National University, Jeonju (Korea, Republic of); Park, Hye Ryoung [Chonnam National University, Gwangju (Korea, Republic of)

    2014-02-15

    A sample with a composition of 90 wt% Mg-10 wt% TaF{sub 5} (named Mg-10TaF{sub 5}) was prepared by reactive mechanical grinding, and its hydriding and dehydriding properties were examined. The activation of Mg-10TaF{sub 5} was not required. At n=1, the sample absorbed 3.63 wt% H for 5 min, 4.03 wt% H for 10 min, and 4.53 wt% H for 30 min at 593 K under 12 bar H2. At n=1, the sample desorbed 0.59 wt% H for 5 min, 1.46 wt% H for 10 min, 3.42 wt% H for 30 min, and 4.24 wt% H for 60 min at 593 K under 1.0 bar H2. Mg-10TaF{sub 5} after reactive mechanical grinding contained MgH{sub 2}, Mg, and very small amounts of MgF{sub 2} and Ta{sub 2}H. The XRD pattern of Mg-10TaF{sub 5} dehydrided at n=3 revealed Mg, MgH{sub 2}, a small amount of MgO, and very small amounts of MgF{sub 2} and Ta{sub 2}H phases. Mg-10Fe{sub 2}O{sub 3} and Mg-10MnO were reported to have quite high hydriding rate and dehydriding rates, respectively. Mg-10TaF{sub 5} had a larger initial hydriding rate but a lower quantity of hydrogen absorbed for 60 min than Mg-10Fe{sub 2}O{sub 3}. However, Mg-10TaF{sub 5} had a higher initial dehydriding rate (after the incubation period) and a larger quantity of hydrogen desorbed for 60 min than Mg-10MnO.

  5. Fuel powder production from ductile uranium alloys

    International Nuclear Information System (INIS)

    Clark, C.R.; Meyer, M.K.

    1998-01-01

    Metallic uranium alloys are candidate materials for use as the fuel phase in very-high-density LEU dispersion fuels. These ductile alloys cannot be converted to powder form by the processes routinely used for oxides or intermetallics. Three methods of powder production from uranium alloys have been investigated within the US-RERTR program. These processes are grinding, cryogenic milling, and hydride-dehydride. In addition, a gas atomization process was investigated using gold as a surrogate for uranium. (author)

  6. Modified Borohydrides for Reversible Hydrogen Storage (2)

    International Nuclear Information System (INIS)

    Ming Au

    2006-01-01

    This paper reports the results in the effort to destabilize lithium borohydride for reversible hydrogen storage. A number of metals, metal hydrides, metal chlorides and complex hydrides were selected and evaluated as the destabilization agents for reducing de-hydriding temperature and generating de-hydriding-re-hydriding reversibility. It is found that some additives are effective. The Raman spectroscopic analysis shows the change of B-H binding nature. (authors)

  7. In-situ investigation of the hydrogen release mechanism in bulk Mg2NiH4

    Science.gov (United States)

    Tran, Xuan Quy; McDonald, Stuart D.; Gu, Qinfen; Yamamoto, Tomokazu; Shigematsu, Koji; Aso, Kohei; Tanaka, Eishi; Matsumura, Syo; Nogita, Kazuhiro

    2017-02-01

    Hydrogen storage is an important aspect to enable the so-called hydrogen economy. Mg-Ni alloys are among the most promising candidates for solid-state hydrogen storage systems yet many questions remain unanswered regarding the hydriding/dehydriding mechanism of the alloys. Mg2NiH4 particularly has received much attention both for its potential as a hydrogen storage medium and also exhibits interesting properties relating to its different polymorphs. Here, the dehydriding mechanism in bulk Mg2NiH4 is investigated using in-situ ultra-high voltage transmission electron microscopy (TEM) combined with Synchrotron powder X-ray diffraction (XRPD) and differential scanning calorimetry (DSC). We find that the hydrogen release is based on a mechanism of nucleation and growth of Mg2NiHx (x∼0-0.3) solid solution grains and is greatly enhanced in the presence of crystal defects occurring as a result of the polymorphic phase transformation. Also importantly, with atomic resolution TEM imaging a high density of stacking faults is identified in the dehydrided Mg2NiHx (x∼0-0.3) lattices.

  8. Characterization of a U-Mo alloy subjected to direct hydriding of the gamma phase

    International Nuclear Information System (INIS)

    Balart, Silvia N.; Bruzzoni, Pablo; Granovsky, Marta S.

    2003-01-01

    The Reduced Enrichment for Research and Test Reactors (RERTR) program has imposed the need to develop plate-type fuel elements based on high density uranium compounds, such as U-Mo alloys. One of the steps in the fabrication of the fuel elements is the pulverization of the fissile material. In the case of the U-Mo alloys, the pulverization can be accomplished through hydriding - dehydriding. Two alternative methods of the hydriding-dehydriding process, namely the selective hydriding in alpha phase (HS-alpha) and the massive hydriding in gamma phase (HM-gamma) are currently being studied at the Comision Nacional de Energia Atomica. The HM-gamma method was reproduced at laboratory scale starting from a U-7 wt % Mo alloy. The hydrided and dehydrided materials were characterized using metallographic techniques, scanning electron microscopy, energy dispersive X-ray analysis and X-ray diffraction. These results are compared with previous results of the HS-alpha method. (author)

  9. The UMo Powder Production Process of UMo-Al Dispersion Fuel for Research Reactor has been Studied

    International Nuclear Information System (INIS)

    Supardjo

    2007-01-01

    Development of UMo-Al dispersion fuel with low enrichment uranium ( 3 ), a relatively large range of γ phase and easily reprocessed. Using UMo alloy as nuclear fuel, uranium density can be increased until 9.0 g/cm 3 , is higher than that of U 3 Si 2 -Al fuel that has only maximum Uranium density 6.0 g/cm 3 . Because of ductility of UMo alloy, thus exact and economic powder production method is needed. Some powder production methods are mechanical crushing (milling, grinding, etc), cryogenic mechanical crushing, atomization, and Hydride-Dehydride. The mechanical crushing and cryogenic mechanical crushing methods are difficult to be performed, time consuming and have high impurity products. However, atomization and hydride-dehydride methods are performed easily, fast and have low impurity products. The product of atomization process is spherical and uniform shape, but, another processes have irregular shape. The evaluation result of some methods showed that hydride-dehydride and atomization methods are more suitable for producing UMo powder than that of another methods. (author)

  10. Alloys for hydrogen storage in nickel/hydrogen and nickel/metal hydride batteries

    Science.gov (United States)

    Anani, Anaba; Visintin, Arnaldo; Petrov, Konstantin; Srinivasan, Supramaniam; Reilly, James J.; Johnson, John R.; Schwarz, Ricardo B.; Desch, Paul B.

    1993-01-01

    Since 1990, there has been an ongoing collaboration among the authors in the three laboratories to (1) prepare alloys of the AB(sub 5) and AB(sub 2) types, using arc-melting/annealing and mechanical alloying/annealing techniques; (2) examine their physico-chemical characteristics (morphology, composition); (3) determine the hydrogen absorption/desorption behavior (pressure-composition isotherms as a function of temperature); and (4) evaluate their performance characteristics as hydride electrodes (charge/discharge, capacity retention, cycle life, high rate capability). The work carried out on representative AB(sub 5) and AB(sub 2) type modified alloys (by partial substitution or with small additives of other elements) is presented. The purpose of the modification was to optimize the thermodynamics and kinetics of the hydriding/dehydriding reactions and enhance the stabilities of the alloys for the desired battery applications. The results of our collaboration, to date, demonstrate that (1) alloys prepared by arc melting/annealing and mechanical alloying/annealing techniques exhibit similar morphology, composition and hydriding/dehydriding characteristics; (2) alloys with the appropriate small amounts of substituent or additive elements: (1) retain the single phase structure, (2) improve the hydriding/dehydriding reactions for the battery applications, and (3) enhance the stability in the battery environment; and (3) the AB(sub 2) type alloys exhibit higher energy densities than the AB(sub 5) type alloys but the state-of-the-art, commercialized batteries are predominantly manufactured using Ab(sub 5) type alloys.

  11. Microcapsulated rare earth - nickel hydride-forming materials

    International Nuclear Information System (INIS)

    Ishikawa, H.; Oguro, K.; Kato, A.; Suzuki, H.; Ishii, E.

    1985-01-01

    Fine particles of hydride-forming alloys such as LaNi/sub 5/ and MmNi/sub 4.5/Mn/sub 0.5/ (MM : mischmetal) were coated with metallic copper thin layer by chemical plating method. Hydrogen storage capacities of alloys were not appreciably affected by the plating treatment. The capsulated alloy powders were easily pressed into pellets. The pellets obtained had high thermal conductivity and porosity enough to permeate hydrogen, leading to fast reaction kinetics. These were able to withstand more than 5,000 repeated hydriding-dehydriding cycles without disintegrating

  12. Amorphous phase formation in intermetallic Mg2Ni alloy synthesized by ethanol wet milling

    International Nuclear Information System (INIS)

    Wang, H.-W.; Chyou, S.-D.; Wang, S.-H.; Yang, M.-W.; Hsu, C.-Y.; Tien, H.-C.; Huang, N.-N.

    2009-01-01

    The hydriding/dehydriding properties of an intermetallic Mg 2 Ni alloy synthesized by wet ball milling in ethanol have been investigated. The appearance of the particle surface after different milling methods is one obvious difference. The alloyed powders prepared by either dry milling or wet milling under ethanol were characterized for phase content by X-ray diffractometer (XRD). The results show that two broad diffuse peaks, which are an ionic-organic-Mg amorphous material, appear in addition to the nickel element peaks. This unexpected amorphous phase has the special hydrogen absorbing/desorbing features.

  13. Performance evaluation and characterisation of EIGA produced titanium alloy powder for additive manufacturing processes

    CSIR Research Space (South Africa)

    Arthur, Nana KK

    2017-11-01

    Full Text Available affect powder quality, and hinder processing. In an investigation by Goso and Kale [3], Ti-6Al-4V alloy powder was produced by the hydride-dehydride (HDH) process in order to make titanium components by blended elemental approach. Chemical analysis.... 2016. Additive manufacturing of metals, Acta Materialia, 117, pp 371-392. 3 [3] Goso, X. and Kale, A. 2010. Production of titanium metal powder by the HDH process, (Paper presented at the South African Institute of Mining and Metallurgy Light...

  14. Ionization Capabilities of Hydronium Ions and High Electric Fields Produced by Atmospheric Pressure Corona Discharge.

    Science.gov (United States)

    Sato, Natsuhiko; Sekimoto, Kanako; Takayama, Mitsuo

    2016-01-01

    Atmospheric pressure corona discharge (APCD) was applied to the ionization of volatile organic compounds. The mass spectra of analytes having aromatic, phenolic, anilinic, basic and aliphatic in nature were obtained by using vapor supply and liquid smear supply methods. The vapor supply method mainly gave protonated analytes [A+H] + caused by proton transfer from hydronium ion H 3 O + , except for benzene, toluene and n -hexane that have lower proton affinity. The use of the liquid smear supply method resulted in the formation of molecular ion A ·+ and/or dehydride analyte [A-H] + , according to the nature of analytes used. The formation of A ·+ without fragment ions could be explained by the electron tunneling via high electric fields 10 8  V/m at the tip of the corona needle. The dehydride analytes [A-H] + observed in the mass spectra of n -hexane, di- and tributylamines may be explained by the hydride abstraction from the alkyl chains by the hydronium ion. The hydronium ion can play the two-roles for analytes, i.e. , the proton donor to form [A+H] + and the hydride acceptor to form [A-H] + .

  15. Comminution of the U-10Mo by hydriding cycles innovative process

    Energy Technology Data Exchange (ETDEWEB)

    Faeda, Kelly C.M.; Santos, Ana Maria M. dos; Paula, Joao B. de; Pereira, Edilson M.; Pedrosa, Tercio A.; Lameiras, Fernando S.; Ferraz, Wilmar B., E-mail: ferrazw@cdtn.br, E-mail: kelly.faeda@prof.una.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

    2013-07-01

    The research, test and producing radioisotopes compact reactors were developed with the use of high levels of enriched fuel of approximately 90% of the fissile isotope U-235. Since the 80s', a policy under the context of international program RERTR (Reduced Enrichment for Research and Test Reactors) encourages the fuel replacement of the high enriched fuel by the low one of about 20 % U-235. One way to compensate the substitution for the low enrichment fuel is to employ high density metal uranium alloys. The fabrication of compact reactor fuel uses the metal matrix dispersion and, for this, uranium alloys are used in the form of powders. Despite the high densities, the metallic uranium based alloys are ductile and therefore difficult to be comminuted. Among the different comminution processes, the hydriding-dehydriding process has proved most advantageous, primarily due to their relative simplicity of processing and low manufacturing cost. In this paper, we present the results of the development of the U-10Mo alloy comminution process by the hydriding-dehydriding method on a laboratory scale. Samples of the alloy were subjected to different hydriding cycle numbers in order to verify its influence in relation to the particle size distribution of powders. Powders of different particle sizes were obtained and characterized by the physical and morphological characteristics by optical microscopy, scanning electron microscopy and X ray diffraction. The obtained results are evaluated and discussed. (author)

  16. CATALYTICALLY ENHANCED SYSTEMS FOR HYDROGEN STORAGE. Final report

    International Nuclear Information System (INIS)

    Craig M. Jensen

    2007-01-01

    Previous U.S. DOE sponsored research at the University of Hawaii resulted in the development of methods of doping of sodium aluminum hydride, NaAlH4 with titanium, zirconium and other catalysts such that: dehydriding occurs at temperatures as low as 100 C; rehydriding requires less than 1 h; and >4 weight percent hydrogen can be repeatedly cycled through dehydriding/rehydriding. These materials appeared to be on the threshold of practical viability as hydrogen carriers for onboard fuel cells. However, it was apparent that further kinetic enhancement was required to achieve commercial viability. Thus, one of the primary goals of this project was to develop the requisite improved catalysts. Over the course of this project, a variety of titanium and zirconium dopant precursors were investigated. Moreover, the approach was to conduct guided search for improved catalysts by obtaining a fundamental understanding of the chemical nature of the titanium dopants and their mechanism of action. Therefore, the projected also aimed to determined the chemical nature of the titanium species that are formed upon mechanical milling of NaAlH4 with the dopant precursors through synchrotron X-ray and neutron diffraction as well as transmission electron microscopy, scanning electron microscopy, and electron paramagnetic resonance (EPR) spectroscopy. In addition to kinetic studies, insight into the mechanism of action of the dopants was gained through studies of the destabilization of hydrogen in NaAlH4 by the dopants through infrared, NMR, and anelastic spectroscopy

  17. Filtration and Hydrogen Reaction Modeling in a Depleted Uranium Bed

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Kwang Jin; Kim, Yean Jin; Ahn, Do Hee; Chung, Hong Suk [UST, Daejeon (Korea, Republic of); Kang, Hee Seok [KAERI, Daejeon (Korea, Republic of); Yun, Sei Hun [NFRI, Daejeon (Korea, Republic of)

    2016-05-15

    The storage and delivery system (SDS) stores the hydrogen isotopes and delivers them to the fuel injection system. Depleted uranium (DU) was chosen as a hydrogen isotope storage material. The hydrogen isotopes stored in the SDS are in the form of DU hydride confined in the primary and secondary containment within a glove box with an argon atmosphere. In this study, we performed a modeling study of the SDS. A modeling study is practically important because an experimental study requires comparatively more money and time. We estimated the hydrogen atomic ratio in DU hydride by two empirical equations we formulated. Two empirical equations are used to determine Pressure-Composition-Temperature (PCT) curves and the hydrogen atomic ratio in DU hydride. In addition, we present the effect of pressure and temperature in the hydriding and dehydriding. A modeling study of the SDS was performed in this study. It is practically important to save more money and time. The hydrogen atomic ratio in the DU hydride was estimated using two empirical equations. The two empirical equations are modified and reformulated to determine PCT curves and the hydrogen atomic ratio in DU hydride. All parameters that are required to solve two empirical equations are obtained from the experimental data. The derived parameters are utilized for the numerical simulations. In the numerical simulations, the effects of pressure and temperature on both the hydriding and dehydriding reaction rates are confirmed.

  18. Evaluation of microstructure and phase relations in a powder processed Ti-44Al-12Nb alloy

    International Nuclear Information System (INIS)

    Kumar, S.G.; Reddy, R.G.; Wu, J.; Holthus, J.

    1995-01-01

    Titanium aluminides based on the ordered face-centered tetragonal γTiAl phase possess attractive properties, such as low density, high melting point, good elevated temperature strength, modulus retention, and oxidation resistance, making these alloys potential high-temperature structural materials. These alloys can be processed by both ingot metallurgy and powder metallurgy routes. In the present study, three variations of the powder metallurgy route were studied to process a Ti-44Al-12Nb (at.%) alloy: (a) cold pressing followed by reaction sintering (CP process); (b) cold pressing, vacuum hot pressing, and then sintering (HP process); and (c) arc melting, hydride-dehydride process to make the alloy powder, cold isostatic pressing, and then sintering (AM process). Microstructural and phase relations were studied by x-ray diffraction (XRD) analysis, optical microscopy, scanning electron microscopy with an energy-dispersive spectrometer (SEM-EDS), and electron probe microanalysis (EPMA). The phases identified were Ti 3 Al and TiAl; an additional Nb 2 Al phase was observed in the HP sample. The microstructures of CP and HP processed samples are porous and chemically inhomogeneous whereas the AM processed sample revealed fine equiaxed microstructure. This refinement of the microstructure is attributed to the fine, homogeneous powder produced by the hydride-dehydride process and the high compaction pressures

  19. Effect of microwave irradiation on hydrogen sorption properties of hand mixed MgH{sub 2} – 10 wt.% carbon fibers

    Energy Technology Data Exchange (ETDEWEB)

    Awad, A.S. [Université de Bordeaux, ICMCB-CNRS, 87 Avenue du Dr Schweitzer, F-33600 Pessac (France); LCPM/PR2N, Université Libanaise, Faculté des Sciences 2, 90656 Jdeidet El Matn (Lebanon); Nakhl, M.; Zakhour, M. [LCPM/PR2N, Université Libanaise, Faculté des Sciences 2, 90656 Jdeidet El Matn (Lebanon); Santos, S.F.; Souza, F.L. [Universidade Federal do ABC, Avenida dos Estados 5001, 09210-580 Santo André – SP (Brazil); Bobet, J.-L., E-mail: jean-louis.bobet@u-bordeaux.fr [Université de Bordeaux, ICMCB-CNRS, 87 Avenue du Dr Schweitzer, F-33600 Pessac (France)

    2016-08-15

    The effect of microwave (MW) irradiation on the hydrogen sorption properties of magnesium powder is explored in the present work. MgH{sub 2} – 10 wt.% CFs (CFs = Carbons Fibers) was prepared by hand mixing, dehydrogenated under microwave irradiation for 20 s and then hydrogenated/dehydrogenated at about 300 °C – 1 MPa and 330 °C–0.03 MPa to investigate the effect of microwave irradiation on the solid/gas sorption properties. It has to be noted that the hydrogen absorption capacity and sorption kinetics of the MgH{sub 2} – 10 wt.% CFs mixture increased after dehydriding under MW irradiation. The MgH{sub 2} – 10 wt.% CFs mixture dehydrogenated by microwave irradiation can absorb about 5.8 wt.% and 5.3 wt.% H at 330 and 300 °C, respectively, within 2 h while the as-prepared MgH{sub 2} – 10 wt.% CFs mixture absorb only 4.6 wt.% H within the same duration. It is also demonstrated that MgH{sub 2} – 10 wt.% CFs mixture dehydrogenated by microwave irradiation exhibited good hydrogen desorption properties and, as an example, a microwave irradiated sample could release 5.8 wt.% H within 1 h at 330 °C in comparison to the as-prepared MgH{sub 2} – 10 wt.% CFs mixture which desorbed 4.4 wt.% H within 3 h. Scanning electron microscopy (SEM) images revealed that the particle sizes of the MW dehydrogenated mixture decreased after several solid/gas sorption cycles. This contribute to the improvement of hydrogen storage properties of the microwaves dehydrogenated MgH{sub 2} – 10 wt.% CFs mixture. In addition, the hydrogenated MgH{sub 2} – 10 wt.% CFs mixture show reproducible and better microwave-assisted dehydriding reaction during second microwaves cycle. - Highlights: • Dehydriding reaction of MgH{sub 2} by microwave method. • Effect of microwaves treatment on the hydrogen sorption properties of Mg. • Effect of discontinuous microwaves irradiation.

  20. Development of a program in LABVIEW platform to controlling and monitoring a Sievert-type system for comminution of metallic uranium and its alloys

    International Nuclear Information System (INIS)

    Dutra, Aimore R.R.; Ferraz, Wilmar B.; Ferreira, Ricardo A.N.

    2011-01-01

    A comminution process by hydriding-dehydriding method was developed at CDTN-Centro de Desenvolvimento da Tecnologia Nuclear with the purpose of obtaining plate type nuclear fuel. This fuel requires the use of metallic uranium and its alloys in form of powders. This comminution process was performed based on a Sievert system. Initially this system was controlled and monitored by a computer program developed in Turbo Pascal language. In order to improve the control of the comminution process, a new program was developed in LabVIEW platform. This paper presents a description of this new program and the main aspects of the operation of the system. The more accurate monitoring and controlling of the various stages of the comminution process as well as greater flexibility in the choice of input data, real-time graphics, generation of reports and a reduction of time passivation were achieved. (author)

  1. Hydrogen induced dis-proportionation studies on Zr-Co-M (M=Ni, Fe, Ti) ternary alloys

    International Nuclear Information System (INIS)

    Jat, Ram Avtar; Pati, Subhasis; Parida, S.C.; Agarwal, Renu; Mukerjee, S.K.; Sastry, P.U.; Jayakrishnan, V.B.

    2016-01-01

    The intermetallic compound ZrCo is considered as a suitable material for storage, supply and recovery of hydrogen isotopes in International Thermonuclear Experimental Reactor (ITER). However, upon repeated hydriding-dehydriding cycles, the hydrogen storage capacity of ZrCo decreases, which is attributed to the disproportionate reaction ZrCo + H 2 ↔ ZrH 2 + ZrCo 2 . The reduction of hydrogen storage capacity of ZrCo is not desirable for its use in tritium facilities. In our previous studies, attempts were made to improve the durability of ZrCo against dis-proportionation by including a third element. The present study is aimed to investigate the hydrogen induced dis-proportionation of Zr-Co-M (M=Ni, Fe and Ti) ternary alloys under hydrogen delivery conditions

  2. Hydrogen isotope storage behavior of Zr1-xTixCo alloys

    International Nuclear Information System (INIS)

    Jat, Ram Avtar; Pati, Subhasis; Parida, S.C.; Agarwal, Renu; Mukerjee, S.K.

    2016-01-01

    Tritium storage properties similar to uranium make ZrCo as a suitable candidate material for storage, supply and recovery of hydrogen isotopes in various tritium facilities. Beside non-radioactive, nonpyrophoric at room temperature and higher storage capacity (H/f.u. up to 3, f.u. = ZrCo), it has been reported that upon repeated hydriding-dehydriding cycles, ZrCo undergoes dis-proportionation as per the reaction; ZrCo + H 2 ↔ ZrH 2 + ZrCo 2 . The present study is aimed to investigate the effect of Ti content on the hydrogen storage behavior of Zr 1-x Ti x Co alloys and the hydrogen isotope effect

  3. Quantifying the properties of low-cost powder metallurgy titanium alloys

    International Nuclear Information System (INIS)

    Bolzoni, L.; Ruiz-Navas, E.M.; Gordo, E.

    2017-01-01

    The extensive industrial employment of titanium is hindered by its high production costs where reduction of these costs can be achieved using cheap alloying elements and appropriate alternative processing techniques. In this work the feasibility of the production of low-cost titanium alloys is addressed by adding steel to pure titanium and processing the alloys by powder metallurgy. In particular, a spherical 4140 LCH steel powder commonly used in metal injection moulding is blended with irregular hydride-dehydride Ti. The new low-cost alloys are cold uniaxially pressed and sintered under high vacuum and show comparable properties to other wrought-equivalent and powder metallurgy titanium alloys. Differential thermal analysis and X-ray diffraction analyses confirm that Ti can tolerate the employment of iron as primary alloying element without forming detrimental TiFe-based intermetallic phases. Thus, the newly designed α+β alloys could be used for cheaper non-critical components.

  4. Room temperature and thermal decomposition of magnesium hydride/deuteride thin films

    Energy Technology Data Exchange (ETDEWEB)

    Ares, J.R.; Leardini, F.; Bodega, J.; Macia, M.D.; Diaz-Chao, P.; Ferrer, I.J.; Fernandez, J.F.; Sanchez, C. [Universidad Autonoma de Madrid (Spain). Lab. de Materiales de Interes en Energias Renovables

    2010-07-01

    Magnesium hydride (MgH{sub 2}) can be considered an interesting material to store hydrogen as long as two main drawbacks were solved: (i) its high stability and (ii) slow (de)hydriding kinetics. In that context, magnesium hydride films are an excellent model system to investigate the influence of structure, morphology and dimensionality on kinetic and thermodynamic properties. In the present work, we show that desorption mechanism of Pd-capped MgH{sub 2} at room temperature is controlled by a bidimensional interphase mechanism and a similar rate step limiting mechanism is observed during thermal decomposition of MgH{sub 2}. This mechanism is different to that occurring in bulk MgH{sub 2} (nucleation and growth) and obtained activation energies are lower than those reported in bulk MgH{sub 2}. We also investigated the Pd-capping properties upon H-absorption/desorption by means of RBS and isotope experiments. (orig.)

  5. Hydridation of Ti-6Al-4V

    International Nuclear Information System (INIS)

    Domizzi, G; Luppo, M.I; Ortiz, M; Vigna, G

    2004-01-01

    The production of Ti pieces or their alloys through powder metallurgy is an economical alternative that replaces the costly methods commonly used. The Ti-6AI-4V alloy is widely used in the aerospace, chemical and medical industries. The use of powder from the alloy instead of using more pure alloyed titanium powders, further simplifies the production process. The presence of V allows the phase β to stabilize at very low temperatures and both alloys alter the Ti-H equilibrium diagram. This work analyzes to what degree these effects influence the obtaining of powders from this alloy from that of hydridation and dehydridation. Although it has slower kinetics, powders can be produced in times similar to those found for grade 2 Ti since the distribution of hydrides in the sample is uniform and the material is fragile enough for concentrations of approximately 0.7 H/Ti (CW)

  6. Fabrication of powder from ductile uranium alloys for use as nuclear dispersion

    International Nuclear Information System (INIS)

    Durazzo, M.; Leal Neto, R.M.; Rocha, C.J.; Urano de Carvalho, E.; Riella, H.G.

    2014-01-01

    This work forms part of the studies presently ongoing at IPEN investigating the feasibility of powdering ductile U-10wt%Mo alloy by hydriding-milling-de-hydriding of the gamma phase (HMD). Hydriding was conducted at room temperature in a Sievert apparatus following heat treatment activation. Hydrided pieces were fragile enough to be hand milled to the desired particle size range. Hydrogen was removed by heating the samples under high vacuum. X-ray diffraction analysis of the hydrided material showed an amorphous-like pattern that is completely reversed following de-hydriding. The hydrogen content of the hydrided samples corresponds to a trihydride, i.e. (U,Mo)H 3 . SEM analysis of HMD powder particles revealed equi-axial powder particles together with some plate-like particles. A hypothesis for the amorphous hydride phase formation is suggested. (authors)

  7. Quantifying the properties of low-cost powder metallurgy titanium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Bolzoni, L., E-mail: bolzoni.leandro@gmail.com [WaiCAM (Waikato Centre for Advanced Materials), The University of Waikato, Private Bag 3105, 3240 Hamilton (New Zealand); Ruiz-Navas, E.M.; Gordo, E. [Department of Materials Science and Engineering, University Carlos III of Madrid, Avda. de la Universidad, 30, 28911 Leganés, Madrid (Spain)

    2017-02-27

    The extensive industrial employment of titanium is hindered by its high production costs where reduction of these costs can be achieved using cheap alloying elements and appropriate alternative processing techniques. In this work the feasibility of the production of low-cost titanium alloys is addressed by adding steel to pure titanium and processing the alloys by powder metallurgy. In particular, a spherical 4140 LCH steel powder commonly used in metal injection moulding is blended with irregular hydride-dehydride Ti. The new low-cost alloys are cold uniaxially pressed and sintered under high vacuum and show comparable properties to other wrought-equivalent and powder metallurgy titanium alloys. Differential thermal analysis and X-ray diffraction analyses confirm that Ti can tolerate the employment of iron as primary alloying element without forming detrimental TiFe-based intermetallic phases. Thus, the newly designed α+β alloys could be used for cheaper non-critical components.

  8. The development of a computational platform to design and simulate on-board hydrogen storage systems

    DEFF Research Database (Denmark)

    Mazzucco, Andrea; Rokni, Masoud

    2017-01-01

    A computational platform is developed in the Modelica® language within the Dymola™ environment to provide a tool for the design and performance comparison of on-board hydrogen storage systems. The platform has been coupled with an open source library for hydrogen fueling stations to investigate...... the vehicular tank within the frame of a complete refueling system. The two technologies that are integrated in the platform are solid-state hydrogen storage in the form of metal hydrides and compressed gas systems. In this work the computational platform is used to compare the storage performance of two tank...... to a storage capacity four times larger than a tube-in-tube solution of the same size. The volumetric and gravimetric densities of the shell and tube are 2.46% and 1.25% respectively. The dehydriding ability of this solution is proven to withstand intense discharging conditions....

  9. Development of a program in LABVIEW platform to controlling and monitoring a Sievert-type system for comminution of metallic uranium and its alloys

    Energy Technology Data Exchange (ETDEWEB)

    Dutra, Aimore R.R.; Ferraz, Wilmar B.; Ferreira, Ricardo A.N., E-mail: ferrazw@cdtn.b, E-mail: ranf@cdtn.b [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

    2011-07-01

    A comminution process by hydriding-dehydriding method was developed at CDTN-Centro de Desenvolvimento da Tecnologia Nuclear with the purpose of obtaining plate type nuclear fuel. This fuel requires the use of metallic uranium and its alloys in form of powders. This comminution process was performed based on a Sievert system. Initially this system was controlled and monitored by a computer program developed in Turbo Pascal language. In order to improve the control of the comminution process, a new program was developed in LabVIEW platform. This paper presents a description of this new program and the main aspects of the operation of the system. The more accurate monitoring and controlling of the various stages of the comminution process as well as greater flexibility in the choice of input data, real-time graphics, generation of reports and a reduction of time passivation were achieved. (author)

  10. Pyrochemical processes for the recovery of weapons grade plutonium either as a metal or as PuO2 for use in mixed oxide reactor fuel pellets

    International Nuclear Information System (INIS)

    Colmenares, C.A.; Ebbinghaus, B.B.; Bronson, M.C.

    1995-01-01

    The authors have developed two processes for the recovery of weapons grade Pu, as either Pu metal or PuO 2 , that are strictly pyrochemical and do not produce any liquid waste. Large amounts of Pu metal (up to 4 kg.), in various geometric shapes, have been recovered by a hydride/dehydride/casting process (HYDEC) to produce metal ingots of any desired shape. The three processing steps are carried out in a single compact apparatus. The experimental technique and results obtained will be described. The authors have prepared PuO 2 powders from weapons grade Pu by a process that hydrides the Pu metal followed by the oxidation of the hydride (HYDOX process). Experimental details of the best way to carry out this process will be presented, as well as the characterization of both hydride and oxide powders produced

  11. Preparation and Hydrogen Storage Properties of Mg-Rich Mg-Ni Ultrafine Particles

    Directory of Open Access Journals (Sweden)

    Jianxin Zou

    2012-01-01

    Full Text Available In the present work, Mg-rich Mg-Ni ultrafine powders were prepared through an arc plasma method. The phase components, microstructure, and hydrogen storage properties of the powders were carefully investigated. It is found that Mg2Ni and MgNi2 could be obtained directly from the vapor state reactions between Mg and Ni, depending on the local vapor content in the reaction chamber. A nanostructured MgH2 + Mg2NiH4 hydrogen storage composite could be generated after hydrogenation of the Mg-Ni ultrafine powders. After dehydrogenation, MgH2 and Mg2NiH4 decomposed into nanograined Mg and Mg2Ni, respectively. Thermogravimetry/differential scanning calorimetry (TG/DSC analyses showed that Mg2NiH4 phase may play a catalytic role in the dehydriding process of the hydrogenated Mg ultrafine particles.

  12. Hydrogen storage behavior of ZrCo1-xNix alloys

    International Nuclear Information System (INIS)

    Jat, Ram Avtar; Parida, S.C.; Agarwal, Renu; Kulkarni, S.G.

    2012-01-01

    Intermetallic compound ZrCo is proposed as a candidate material for storage, supply and recovery of hydrogen isotopes in International Thermonuclear Experimental Reactor (ITER) Storage and Delivery System (SDS). However, it has been reported that upon repeated hydriding-dehydriding cycles, ZrCo undergoes disproportionation as per the reaction; 2ZrCo + H 2 ↔ ZrH 2 + ZrCO 2 . This results in reduction in hydrogen storage capacity of ZrCo, which is not a desirable property for SDS. Konishi et al. reported that the disproportionation reaction can be suppressed by decreasing the desorption temperature. It is anticipated that suitable ternary alloying of ZrCo can elevated the hydrogen equilibrium pressure and hence decrease the desorption temperature for supply of 100 kPa of hydrogen. In this study, we have investigated the effect of Ni content on the hydrogenation behavior of ZrCo 1-x Ni x alloys

  13. The United States pit disassembly and conversion project -- Meeting the MOX fuel specification

    International Nuclear Information System (INIS)

    Nelson, T.O.; James, C.A.; Kolman, D.G.

    1998-01-01

    The US is actively involved in demonstrating the disassembly of nuclear weapons pits to an unclassified form readied for disposition. The MOX option is the most likely path forward for plutonium that originated from nuclear weapon pits. The US demonstration line for pit disassembly and conversion is known as ARIES, the advanced recovery and integrated extraction system. The ARIES demonstration line is being used to gather data in an integrated fashion of the technologies needed for pit disassembly and conversion. These activities include the following modules: pit bisection, hydride-dehydride, oxide conversion, canning, electrolytic decontamination, and nondestructive assay (NDA). Pit bisection swages in a pit in half. Hydride-dehydride converts the pit plutonium metal to an unclassified metal button. To convert the plutonium metal to an oxide the US is investigating a number of options. The primary oxide conversion approach involves variations of combining plutonium hydriding and subsequent oxidation. Another approach is to simply oxidize the metal under controlled conditions-direct metal oxidation (DMO). To remove the gallium from the plutonium oxide, a thermal distillation approach is being used. These pyrochemical approaches will substantially reduce the wastes produced for oxide conversion of weapon plutonium, compared to traditional aqueous processing. The packaging of either the plutonium metal or oxide to long term storage criteria involves the canning and electrolytic decontamination modules. The NDA suite of instruments is then used to assay the material in the containers, which enables international verification without the need to open the containers and repackage them. All of these processes are described

  14. Hydrogen storage properties of LaMgNi3.6M0.4 (M = Ni, Co, Mn, Cu, Al) alloys

    International Nuclear Information System (INIS)

    Yang, Tai; Zhai, Tingting; Yuan, Zeming; Bu, Wengang; Xu, Sheng; Zhang, Yanghuan

    2014-01-01

    Highlights: • La–Mg–Ni system AB 2 -type alloys were prepared by induction melting. • Structures and lattice parameters were analysed by XRD. • Hydrogen absorption/desorption performances were studied. • Mechanisms of hydrogen absorption capacity fading were investigated. - Abstract: LaMgNi 3.6 M 0.4 (M = Ni, Co, Mn, Cu, Al) alloys were prepared through induction melting process. The phase compositions and crystal structures were characterised via X-ray diffraction (XRD). The hydrogen storage properties, including activation performance, hydrogen absorption capacity, cycle stability, alloy particle pulverisation and plateau pressure, were systemically investigated. Results show that Ni, Co, Mn and Cu substitution alloys exhibit multiphase structures comprising the main phase LaMgNi 4 and the secondary phase LaNi 5 . However, the secondary phase of the Al substitution alloy changes into LaAlNi 4 . The lattice parameters and cell volumes of the LaMgNi 4 phase follow the order Ni < Co < Al < Cu < Mn. Activation is simplified through partial substitution of Ni with Al, Cu and Co. The hydrogen absorption capacities of all of the alloys are approximately 1.7 wt.% at the first activation process; however, they rapidly decrease with increasing cycle number. In addition, the stabilities of hydriding and dehydriding cycles decrease in the order Al > Co > Ni > Cu > Mn. Hydriding processes result in numerous cracks and amorphisation of the LaMgNi 4 phase in the alloys. The p–c isotherms were determined by a Sieverts-type apparatus. Two plateaus were observed for the Ni, Co and Al substitution alloys, whereas only one plateau was found for Mn and Cu. This result was caused by the amorphisation of the LaMgNi 4 phase during the hydriding cycles. Reversible absorption and desorption of hydrogen are difficult to achieve. Substitutions of Ni with Co, Mn, Cu and Al significantly influence the reduction of hysteresis between hydriding and dehydriding

  15. PEMBUATAN SERBUK U-6Zr DENGAN PENGKAYAAN URANIUM 19,75 % UNTUK BAHAN BAKAR REAKTOR RISET

    Directory of Open Access Journals (Sweden)

    Masrukan Masrukan

    2016-03-01

    Full Text Available ABSTRAK PEMBUATAN SERBUK PADUAN U-6Zr DENGAN PENGKAYAAN URANIUM 19,75 % UNTUK BAHAN BAKAR REAKTOR RISET. Telah dilakukan pembuatan serbuk paduan U-6Zr dengan pengkayaan 19,75 % untuk bahan bakar reaktor riset. Pembuatan bahan bakar U-6Zr ini dalam rangka mencari bahan bakar baru yang mempunyai densitas tinggi untuk mengganti bahan bakar yang sudah ada U3Si2-Al. Tujuan dari percobaan ini untuk mengetahui sifat-sifat serbuk paduan U- 6Zr yang diperoleh dari proses hydriding-dehydriding sebagai kandidat bahan bakar reaktor riset. Serbuk yang diperoleh dari proses hydriding-dehydriding dikenai pengujian, diantaranya pungujian komposisi kimia, densitas, kandungan hidrogen, fasa dan sifat termal. Hasil pengujian komposisi kimia menunjukkan beberapa unsur seperti Al, Ca, Cu, dan Ni melebihi batas yang diijinkan dimana masing-masing unsur terdapat sebesar 202,21 ppm; 214,05 ppm; 61,25 ppm dan 134,53 ppm. Pada pengujian diperolah densitas serbuk U-6Zr sebesar 13,58 g/cm3 dan pada pengujian kandungan hidrogen sisa diperoleh kandungan hidrogen sebesar 0,16 %. Untuk pengujian fasa, diperoleh fasa αU dan δU, sedangkan pada pengujian sifat termal yakni transformasi temperatur terdapat dua puncak yakni puncak pertama terjadi pada temperatur 274 hingga 311 oC dan puncak kedua terjadi pada temperatur 493 hingga 527oC. Puncak pertama terjadi reaksi endotermik dengan menyerap panas sebesar ∆H = 6,23 cal/g tetapi tidak terbentuk fasa baru, sedangkan puncak kedua terjadi reaksi eksotermik dengan mengeluarkan panas sebesar ∆H = -9.34 cal/g dan terbentuk fasa αZr. Sementara itu, dari pengujian kapasitas panas pada temperatur 34 hingga 75 oC, terjadinya penurunan nilai kapasitas panas yang disertai dengan penyerapan panas. Pada temperatur yang lebih tinggi hingga temperatur 437oC nilai kapasitas panas menjadi lebih kecil disertai pengeluaran panas. Reaksi termokimia antara Zr dengan hidrogen sisa menunjukkan terbentuknya fasa αZr yang diindikasikan oleh reaksi

  16. Decomposition kinetics of plutonium hydride

    Energy Technology Data Exchange (ETDEWEB)

    Haschke, J.M.; Stakebake, J.L.

    1979-01-01

    Kinetic data for decomposition of PuH/sub 1/ /sub 95/ provides insight into a possible mechanism for the hydriding and dehydriding reactions of plutonium. The fact that the rate of the hydriding reaction, K/sub H/, is proportional to P/sup 1/2/ and the rate of the dehydriding process, K/sub D/, is inversely proportional to P/sup 1/2/ suggests that the forward and reverse reactions proceed by opposite paths of the same mechanism. The P/sup 1/2/ dependence of hydrogen solubility in metals is characteristic of the dissociative absorption of hydrogen; i.e., the reactive species is atomic hydrogen. It is reasonable to assume that the rates of the forward and reverse reactions are controlled by the surface concentration of atomic hydrogen, (H/sub s/), that K/sub H/ = c'(H/sub s/), and that K/sub D/ = c/(H/sub s/), where c' and c are proportionality constants. For this surface model, the pressure dependence of K/sub D/ is related to (H/sub s/) by the reaction (H/sub s/) reversible 1/2H/sub 2/(g) and by its equilibrium constant K/sub e/ = (H/sub 2/)/sup 1/2//(H/sub s/). In the pressure range of ideal gas behavior, (H/sub s/) = K/sub e//sup -1/(RT)/sup -1/2/ and the decomposition rate is given by K/sub D/ = cK/sub e/(RT)/sup -1/2/P/sup 1/2/. For an analogous treatment of the hydriding process with this model, it can be readily shown that K/sub H/ = c'K/sub e//sup -1/(RT)/sup -1/2/P/sup 1/2/. The inverse pressure dependence and direct temperature dependence of the decomposition rate are correctly predicted by this mechanism which is most consistent with the observed behavior of the Pu--H system.

  17. Hydrogen storage properties of LaMgNi{sub 3.6}M{sub 0.4} (M = Ni, Co, Mn, Cu, Al) alloys

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Tai [Department of Functional Material Research, Central Iron and Steel Research Institute, Beijing 100081 (China); Key Laboratory of Integrated Exploitation of Baiyun Obo Multi-Metal Resources, Inner Mongolia University of Science and Technology, Baotou 014010 (China); Zhai, Tingting; Yuan, Zeming; Bu, Wengang [Department of Functional Material Research, Central Iron and Steel Research Institute, Beijing 100081 (China); Xu, Sheng [Key Laboratory of Integrated Exploitation of Baiyun Obo Multi-Metal Resources, Inner Mongolia University of Science and Technology, Baotou 014010 (China); Zhang, Yanghuan, E-mail: zhangyh59@sina.com [Department of Functional Material Research, Central Iron and Steel Research Institute, Beijing 100081 (China); Key Laboratory of Integrated Exploitation of Baiyun Obo Multi-Metal Resources, Inner Mongolia University of Science and Technology, Baotou 014010 (China)

    2014-12-25

    Highlights: • La–Mg–Ni system AB{sub 2}-type alloys were prepared by induction melting. • Structures and lattice parameters were analysed by XRD. • Hydrogen absorption/desorption performances were studied. • Mechanisms of hydrogen absorption capacity fading were investigated. - Abstract: LaMgNi{sub 3.6}M{sub 0.4} (M = Ni, Co, Mn, Cu, Al) alloys were prepared through induction melting process. The phase compositions and crystal structures were characterised via X-ray diffraction (XRD). The hydrogen storage properties, including activation performance, hydrogen absorption capacity, cycle stability, alloy particle pulverisation and plateau pressure, were systemically investigated. Results show that Ni, Co, Mn and Cu substitution alloys exhibit multiphase structures comprising the main phase LaMgNi{sub 4} and the secondary phase LaNi{sub 5}. However, the secondary phase of the Al substitution alloy changes into LaAlNi{sub 4}. The lattice parameters and cell volumes of the LaMgNi{sub 4} phase follow the order Ni < Co < Al < Cu < Mn. Activation is simplified through partial substitution of Ni with Al, Cu and Co. The hydrogen absorption capacities of all of the alloys are approximately 1.7 wt.% at the first activation process; however, they rapidly decrease with increasing cycle number. In addition, the stabilities of hydriding and dehydriding cycles decrease in the order Al > Co > Ni > Cu > Mn. Hydriding processes result in numerous cracks and amorphisation of the LaMgNi{sub 4} phase in the alloys. The p–c isotherms were determined by a Sieverts-type apparatus. Two plateaus were observed for the Ni, Co and Al substitution alloys, whereas only one plateau was found for Mn and Cu. This result was caused by the amorphisation of the LaMgNi{sub 4} phase during the hydriding cycles. Reversible absorption and desorption of hydrogen are difficult to achieve. Substitutions of Ni with Co, Mn, Cu and Al significantly influence the reduction of hysteresis between

  18. Experimental study of a metal hydride driven braided artificial pneumatic muscle

    Science.gov (United States)

    Vanderhoff, Alexandra; Kim, Kwang J.

    2009-12-01

    This paper reports the experimental study of a new actuation system that couples a braided artificial pneumatic muscle (BAPM) with a metal hydride driven hydrogen compressor to create a compact, lightweight, noiseless system capable of high forces and smooth actuation. The results indicate that the metal hydride-BAPM system has relatively good second law efficiency average of 30% over the desorption cycle. The thermal efficiency is low, due mainly to the highly endothermic chemical reaction that releases the stored hydrogen gas from the metal hydride. The force to metal hydride weight is very high (~14 000 NForce/kgMH) considering that this system has not been optimized to use the minimum amount of metal hydride required for a full actuation stroke of the fluidic muscle. Also, a thermodynamic model for the complete system is developed. The analysis is restricted in some aspects concerning the complexity of the hydriding/dehydriding chemical process of the system and the three-dimensional geometry of the reactor, but it provides a useful comparison to other actuation devices and clearly reveals the parameters necessary for optimization of the actuation system in future work. The system shows comparable work output and has the benefits of biological muscle-like properties for potential use in robotic systems.

  19. Experimental study of a metal hydride driven braided artificial pneumatic muscle

    International Nuclear Information System (INIS)

    Vanderhoff, Alexandra; Kim, Kwang J

    2009-01-01

    This paper reports the experimental study of a new actuation system that couples a braided artificial pneumatic muscle (BAPM) with a metal hydride driven hydrogen compressor to create a compact, lightweight, noiseless system capable of high forces and smooth actuation. The results indicate that the metal hydride–BAPM system has relatively good second law efficiency average of 30% over the desorption cycle. The thermal efficiency is low, due mainly to the highly endothermic chemical reaction that releases the stored hydrogen gas from the metal hydride. The force to metal hydride weight is very high (∼14 000 N Force /kg MH ) considering that this system has not been optimized to use the minimum amount of metal hydride required for a full actuation stroke of the fluidic muscle. Also, a thermodynamic model for the complete system is developed. The analysis is restricted in some aspects concerning the complexity of the hydriding/dehydriding chemical process of the system and the three-dimensional geometry of the reactor, but it provides a useful comparison to other actuation devices and clearly reveals the parameters necessary for optimization of the actuation system in future work. The system shows comparable work output and has the benefits of biological muscle-like properties for potential use in robotic systems

  20. Dislocation/hydrogen interaction mechanisms in hydrided nanocrystalline palladium films

    International Nuclear Information System (INIS)

    Amin-Ahmadi, Behnam; Connétable, Damien; Fivel, Marc; Tanguy, Döme; Delmelle, Renaud; Turner, Stuart; Malet, Loic; Godet, Stephane; Pardoen, Thomas; Proost, Joris; Schryvers, Dominique

    2016-01-01

    The nanoscale plasticity mechanisms activated during hydriding cycles in sputtered nanocrystalline Pd films have been investigated ex-situ using advanced transmission electron microscopy techniques. The internal stress developing within the films during hydriding has been monitored in-situ. Results showed that in Pd films hydrided to β-phase, local plasticity was mainly controlled by dislocation activity in spite of the small grain size. Changes of the grain size distribution and the crystallographic texture have not been observed. In contrast, significant microstructural changes were not observed in Pd films hydrided to α-phase. Moreover, the effect of hydrogen loading on the nature and density of dislocations has been investigated using aberration-corrected TEM. Surprisingly, a high density of shear type stacking faults has been observed after dehydriding, indicating a significant effect of hydrogen on the nucleation energy barriers of Shockley partial dislocations. Ab-initio calculations of the effect of hydrogen on the intrinsic stable and unstable stacking fault energies of palladium confirm the experimental observations.

  1. Tritium storage metal-bed pyrophoricity measurements

    International Nuclear Information System (INIS)

    Longhurst, G.R.; Neilson, R.M. Jr.; Porter, L.J.

    1987-01-01

    A safety concern for metal-bed tritium storage systems is the possibility of spontaneous combustion and/or explosion if the bed is accidentally exposed to air. This may result in the dispersion of tritium or tritiated compounds. Of several materials being considered for use in tritium storage beds, uranium (U), zirconium-cobalt (ZrCo), and lanthanum-nickel aluminide (LaNi 5-x Al x ) are of particular interest. It is well known that uranium that has been activated by cycles of hydriding and dehydriding is extremely pyrophoric when exposed to air or other oxidizers. Uranium hydride has also been found to be mildly pyrophoric, but less is known about the pyrophoric natures of the hydrides of the other materials. An experiment is in progress to evaluate the pyrophoric response of these materials and their hydrides and deuterides in air. Small (<100 mg) samples of depleted uranium were hydrided and then exposed to atmospheres of air, oxygen, or nitrogen using a thermogravimetric analyzer to monitor the sample weight and temperature. There was not an immediate pyrophoric response at room temperature, but ignition occured at moderately elevated temperatures for air and oxygen atmospheres. The experimental apparatus has been upgraded, and tests are continuing on these materials

  2. Improved hydrogen absorption and desorption kinetics of magnesium-based alloy via addition of yttrium

    Science.gov (United States)

    Yang, Tai; Li, Qiang; Liu, Ning; Liang, Chunyong; Yin, Fuxing; Zhang, Yanghuan

    2018-02-01

    Yttrium (Y) is selected to modify the microstructure of magnesium (Mg) to improve the hydrogen storage performance. Thereby, binary alloys with the nominal compositions of Mg24Yx (x = 1-5) are fabricated by inexpensive casting technique. Their microstructure and phase transformation during hydriding and dehydriding process are characterized by using X-ray diffraction, scanning electron microscopy, and high-resolution transmission electron microscopy analysis. The isothermal hydrogen absorption and desorption kinetics are also measured by a Sievert's-type apparatus at various temperatures. Typical multiphase structures of binary alloy can be clearly observed. All of these alloys can reversibly absorb and desorb large amount of hydrogen at proper temperatures. The addition of Y markedly promotes the hydrogen absorption kinetics. However, it results in a reduction of reversible hydrogen storage capacity. A maximum value of dehydrogenation rate is observed with the increase of Y content. The Mg24Y3 alloy has the optimal desorption kinetic performance, and it can desorb about 5.4 wt% of hydrogen at 380 °C within 12 min. Combining Johnson-Mehl-Avrami kinetic model and Arrhenius equation, the dehydrogenation activation energy of the alloys are evaluated. The Mg24Y3 alloy also has the lowest dehydrogenation activation energy (119 kJ mol-1).

  3. Formation and mechanism of nanocrystalline AZ91 powders during HDDR processing

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yafen; Fan, Jianfeng, E-mail: fanjianfeng@tyut.edu.cn; Zhang, Hua; Zhang, Qiang; Gao, Jing; Dong, Hongbiao, E-mail: hd38@leicester.ac.uk; Xu, Bingshe

    2017-03-15

    Grain sizes of AZ91 alloy powders were markedly refined to about 15 nm from 100 to 160 μm by an optimized hydrogenation-disproportionation-desorption-recombination (HDDR) process. The effect of temperature, hydrogen pressure and processing time on phase and microstructure evolution of AZ91 alloy powders during HDDR process was investigated systematically by X-ray diffraction, optical microscopy, scanning electron microscopy and transmission electron microscopy, respectively. The optimal HDDR process for preparing nanocrystalline Mg alloy powders is hydriding at temperature of 350 °C under 4 MPa hydrogen pressure for 12 h and dehydriding at 350 °C for 3 h in vacuum. A modified unreacted core model was introduced to describe the mechanism of grain refinement of during HDDR process. - Highlights: • Grain size of the AZ91 alloy powders was significantly refined from 100 μm to 15 nm. • The optimal HDDR technology for nano Mg alloy powders is obtained. • A modified unreacted core model of grain refinement mechanism was proposed.

  4. Irreversible effects in the FeTi/H system

    International Nuclear Information System (INIS)

    Reilly, J.J.; Johnson, J.R.; Lynch, J.F.; Reidinger, F.

    1982-03-01

    The equilibrium hydrogen absorption isotherm using annealed, strain-free FeTi, exhibits only one plateau up to a composition of FeTiH/sub 1.95/. However, the desorption isotherm, determined immediately after the first hydriding step, exhibits the usual two plateaux. X-ray diffraction results of samples with compositions within the absorption plateau limits indicate the major phases present to be α and γ, although a small amount of β phase was always detected. Apparently the absorption isotherm represents the direct conversion of α → γ and β phase precipitation is almost completely suppressed. Thermodynamic quantities for this conversion are given. The results are attributed to the influence of lattice strain upon the behavior of the β1 and β2 phases. A practical consequence of the effect is the distortion of the pressure-composition isotherm in the β-γ region as a function of hydriding-dehydriding cycles. This is caused by an increase in H solubility of the β and γ phases and the widening of the phase composition limits as the strain increases with cycle number. However, after many hundreds of cycles there is no further significant increase in strain and the isotherm shape becomes essentially fixed and reproducible. The distortion is reversible by mild annealing

  5. Indications of the formation of an oversaturated solid solution during hydrogenation of Mg-Ni based nanocomposite produced by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Guzman, D. [Departamento de Ingenieria en Metalurgia, Facultad de Ingenieria, Universidad de Atacama y Centro Regional de Investigacion y Desarrollo Sustentable de Atacama, CRIDESAT, Av. Copayapu 485, Copiapo (Chile); Ordonez, S. [Departamento de Ingenieria Metalurgica, Facultad de Ingenieria, Universidad de Santiago de Chile, Av. Lib. Bernardo O' Higgins 3363, Santiago (Chile); Fernandez, J.F.; Sanchez, C. [Departamento de Fisica de Materiales, Facultad de Ciencias, Universidad Autonoma de Madrid, Cantoblanco 28049, Madrid (Spain); Serafini, D. [Departamento de Fisica, Facultad de Ciencias, Universidad de Santiago de Chile and Center for Interdisciplinary Research in Materials, CIMAT, Av. Lib. Bernardo O' Higgins 3363, Santiago (Chile); Rojas, P.A. [Escuela de Ingenieria Mecanica, Facultad de Ingenieria, Av. Los Carrera 01567, Quilpue, Pontificia Universidad Catolica de Valparaiso, PUCV (Chile); Aguilar, C. [Instituto de Materiales y Procesos Termomecanicos, Facultad de Ciencias de la Ingenieria, Universidad Austral de Chile, Av. General Lagos 2086, Valdivia (Chile)

    2009-07-15

    An oversaturated solid solution of H in a nanocomposite material formed mainly by nanocrystalline Mg{sub 2}Ni, some residual nanocrystalline Ni and an Mg rich amorphous phase has been found for the first time. The nanocomposite was produced by mechanical alloying starting from Mg and Ni elemental powders, using a SPEX 8000D mill. The hydriding characterization of the nanocomposite was carried out by solid-gas reaction method in a Sievert's type apparatus. The maximum hydrogen content reached in a period of 21 Ks without prior activation was 2.00 wt.% H under hydrogen pressure of 2 MPa at 363 K. The X-ray diffraction analysis showed the presence of an oversaturated solid solution between nanocrystalline Mg{sub 2}Ni and H without any sign of Mg{sub 2}NiH{sub 4} hydride formation. The dehydriding behaviour was studied by differential scanning calorimetry and thermogravimetry. The results showed the existence of two desorption peaks, the first one associated with the transformation of the oversaturated solid solution into Mg{sub 2}NiH{sub 4}, and the second one with the Mg{sub 2}NiH{sub 4} desorption. (author)

  6. Production of a low young modulus titanium alloy by powder metallurgy

    Directory of Open Access Journals (Sweden)

    Dalcy Roberto dos Santos

    2005-12-01

    Full Text Available Titanium alloys have several advantages over ferrous and non-ferrous metallic materials, such as high strengthto-weight ratio and excellent corrosion resistance. A blended elemental titanium powder metallurgy process has been developed to offer low cost commercial products. The process employs hydride-dehydride (HDH powders as raw material. In this work, results of the Ti-35Nb alloy sintering are presented. This alloy due to its lower modulus of elasticity and high biocompatibility is a promising candidate for aerospace and medical use. Samples were produced by mixing of initial metallic powders followed by uniaxial and cold isostatic pressing with subsequent densification by isochronal sintering between 900 up to 1600 °C, in vacuum. Sintering behavior was studied by means of microscopy and density. Sintered samples were characterized for phase composition, microstructure and microhardness by X-ray diffraction, scanning electron microscopy and Vickers indentation, respectively. Samples sintered at high temperatures display a fine plate-like alpha structure and intergranular beta. A few remaining pores are still found and density above 90% for specimens sintered in temperatures over 1500 °C is reached.

  7. U-Mo Alloy Powder Obtained Through Selective Hydriding. Particle Size Control

    International Nuclear Information System (INIS)

    Balart, S.N.; Bruzzoni, P.; Granovsky, M.S.

    2002-01-01

    Hydride-dehydride methods to obtain U-Mo alloy powder for high-density fuel elements have been successfully tested by different authors. One of these methods is the selective hydriding of the α phase (HSα). In the HSα method, a key step is the partial decomposition of the γ phase (retained by quenching) to α phase and an enriched γ phase or U 2 Mo. This transformation starts mainly at grain boundaries. Subsequent hydrogenation of this material leads to selective hydriding of the α phase, embrittlement and intergranular fracture. According to this picture, the particle size of the final product should be related to the γ grain size of the starting alloy. The feasibility of controlling the particle size of the product by changing the γ grain size of the starting alloy is currently investigated. In this work an U-7 wt% Mo alloy was subjected to various heat treatments in order to obtain different grain sizes. The results on the powder particle size distribution after applying the HSα method to these samples show that there is a strong correlation between the original γ grain size and the particle size distribution of the powder. (author)

  8. Hydrogen storage via polyhydride complexes

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, C.M.; Zidan, R.A. [Univ. of Hawaii, Honolulu, HI (United States)

    1998-08-01

    The reversible dehydrogenation of NaAlH{sub 4} is catalyzed in toluene slurries of the NaAlH{sub 4} containing the pincer complex, IrH{sub 4} {l_brace}C{sub 6}H{sub 3}-2,6-(CH{sub 2}PBu{sup t}{sub 2}){sub 2}{r_brace}. The rates of the pincer complex catalyzed dehydrogenation are about five times greater those previously found for NaAlH{sub 4} that was doped with titanium through a wet chemistry method. Homogenization of NaAlH{sub 4} with 2 mole % Ti(OBu{sup n}){sub 4} under an atmosphere of argon produces a novel titanium containing material. TPD measurements show that the dehydrogenation of this material occurs about 30 C lower than that previously found for wet titanium doped NaAlH{sub 4}. In further contrast to wet doped NaAlH{sub 4}, the dehydrogenation kinetics and hydrogen capacity of the novel material are undiminished over several dehydriding/hydriding cycles. Rehydrogenation of the titanium doped material occurs readily at 170 C under 150 atm of hydrogen. TPD measurements show that about 80% of the original hydrogen content (4.2 wt%) can be restored under these conditions.

  9. Effect of starting materials and processing variables for the production of discontinuous filament Nb3Sn wire

    International Nuclear Information System (INIS)

    Upadhyay, P.L.; Dew-Hughes, D.

    1986-01-01

    Discontinuous multifilamentary wires of Nb 3 Sn have been prepared from compacted mixtures of 30 wt. %Nb in Cu, extruded, drawn, annealed, tin plated and reacted. Processing variables include starting materials, extrusion ratio and extrusion temperature. Continuous lengths of wire could be satisfactorily produced from compacts of either ultra-pure Nb (VPN about 95 kg mm -2 ) and Cu powder or from centrifugal arc-cast Nb spheroids (VPN about 120 kg mm -2 ) and tough pitch Cu powder. After a total area reduction of 10 4 : 1, the latter materials resulted in long, unbroken, highly regular filaments of Nb about 6μm in diameter. The high degree of perfection of these filaments is due in part to the uniformity of the initial spheroids, compared to the highly irregular hydride-dehydride Nb powder. However their greater hardness requires that the spheroids be coprocessed in a less-pure Cu matrix. Critical currents were measured on helical specimens involving more than 1m length of wire, in fields up to 15T at 4.2 K, after reaction for various times at different temperatures. Overall current densities of 3 X 10 8 Am -2 were obtained at 12T in the best samples. Further reductions are expected to produce material with improved current densities

  10. Effect of annealing treatment on structure and electrochemical performance of quenched MmNi4.2Co0.3Mn0.4Al0.3Mg0.03 hydrogen storage alloy

    International Nuclear Information System (INIS)

    Zhou Zenglin; Song Yueqing; Cui Shun; Huang Changgeng; Qian Wenlian; Lin Chenguang; Zhang Yongjian; Lin Yulin

    2010-01-01

    MmNi 4.2 Co 0.3 Mn 0.4 Al 0.3 Mg 0.03 hydrogen storage alloy was prepared by single-roll rapid quenching followed by different annealing treatments for 8 h at 1133 K, 1173 K, 1213 K, and 1253 K, respectively. Alloy structure, phase composition, pressure-composition-temperature (PCT) properties, and electrochemical performance of different annealed alloys have been investigated by X-ray diffraction (XRD), field-emission scanning electron microscope (FESEM), energy dispersion spectrometer (EDS), automatic Sieverts-type apparatus, and electrochemical experiments. Electrochemical experiments indicate that the annealing treatment at 1213 K extends cycle life from 193 cycles to 358 cycles, increases the maximum discharge capacity, and slightly decreases the activation behavior. Alloy structure analyses show that the improvement in cycle life is attributed to the formation of a single CaCu 5 -type structure or the relief of an Mg-containing AlMnNi 2 -type second phase. Pressure composition isotherms results illustrate that both the hydrogen absorption capability and the dehydriding equilibrium pressure go up with increased annealing temperature. For its good performance/cost ratio, the Mg-added low-Co alloy annealed at 1213 K would be a promising substitution for MmNi 4.05 Co 0.45 Mn 0.4 Al 0.3 alloy product.

  11. Evolution of microstructure of U-Mo alloys in as cast and sintered forms

    International Nuclear Information System (INIS)

    Sinha, V.P.; Hegde, P.V.; Prasad, G.J.; Kamath, H.S.; Dey, G.K.

    2009-01-01

    Over the years U 3 Si 2 compound dispersed in aluminium matrix has been successfully used as potential Low Enriched Uranium (LEU 235 ) base dispersion fuel in new research and test reactors and also for converting High Enriched Uranium (HEU > 85% U 235 ) cores to LEU in most of the existing research and test reactors. The maximum density achievable with U 3 Si 2 -AI dispersion fuel is around 4.8 g U cm -3 . To achieve a uranium density of 8.0 to 9.0 g U cm -3 in dispersion fuel with aluminium as matrix material, it is required to use γ-stabilized uranium metal powders. At Metallic Fuels Division, R and D efforts are on to develop these high density uranium alloys. Molybdenum plays a crucial role in metastabilising the γ-phase of uranium at room temperature which is very much evident when we see the microstructures of different U-Mo alloys with varying molybdenum concentration as solute atom. The paper describes the role of molybdenum in imparting metastability in U-Mo alloys from their microstructures in as cast and sintered forms. The paper also covers the role of tailored microstructure in U-Mo alloy for the purpose of hydriding and dehydriding treatment to generate alloy powders. (author)

  12. Improved hydrogen storage properties of MgH2 catalyzed with TiO2

    Science.gov (United States)

    Jangir, Mukesh; Meena, Priyanka; Jain, I. P.

    2018-05-01

    In order to improve the hydrogenation properties of the MgH2, various concentration of rutile Titanium Oxide (TiO2) (X wt%= 5, 10, 15 wt %) is added to MgH2 by ball milling and the catalytic effect of TiO2 on hydriding/dehydriding properties of MgH2 has been investigated. Result shows that the TiO2 significantly reduced onset temperature of desorption. Onset temperature as low as 190 °C were observed for the MgH2-15 wt% TiO2 sample which is 60 °C and 160 °C lower than the as-milled and as-received MgH2. Fromm the Kissinger plot the activation energy of 15 wt% TiO2 added sample is calculated to be -75.48 KJ/mol. These results indicate that the hydrogenation properties of MgH2-TiO2 have been improved compared to the as-milled and as-received MgH2. Furthermore, XRD and XPS were performed to characterize the structural evolution upon milling and dehydrogenation.

  13. A new reversible Mg3Ag–H2 system for hydrogen storage

    International Nuclear Information System (INIS)

    Si, T.Z.; Zhang, J.B.; Liu, D.M.; Zhang, Q.A.

    2013-01-01

    Highlights: •Mg 3 Ag compound with high-purity was prepared by hydrogen metallurgy. •Mg 3 Ag is first employed for reversible hydrogen storage with altered thermodynamics. •The enhanced cyclic stability is due to the prevention of MgH 2 sintering by MgAg. -- Abstract: For the first time, the compound Mg 3 Ag was employed as a medium for hydrogen storage. It has been demonstrated that the hydriding/dehydriding process of Mg 3 Ag is reversible through the reaction Mg 3 Ag + 2H 2 ↔ 2MgH 2 + MgAg with obtaining altered thermodynamics. An enhanced cycling stability is also achieved by the capacity retention of 95% after 30 cycles, much higher than 70% for the pure Mg sample, which can be explained that the agglomeration and sintering of the resulting MgH 2 are efficiently prevented by the formation of hard and brittle MgAg phase upon multi-cycling

  14. Implementing waste minimization at an active plutonium processing facility: Successes and progress at technical area (TA) -55 of the Los Alamos National Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Balkey, J.J.; Robinson, M.A.; Boak, J.

    1997-12-01

    The Los Alamos National Laboratory has ongoing national security missions that necessitate increased plutonium processing. The bulk of this activity occurs at Technical Area -55 (TA-55), the nations only operable plutonium facility. TA-55 has developed and demonstrated a number of technologies that significantly minimize waste generation in plutonium processing (supercritical CO{sub 2}, Mg(OH){sub 2} precipitation, supercritical H{sub 2}O oxidation, WAND), disposition of excess fissile materials (hydride-dehydride, electrolytic decontamination), disposition of historical waste inventories (salt distillation), and Decontamination & Decommissioning (D&D) of closed nuclear facilities (electrolytic decontamination). Furthermore, TA-55 is in the process of developing additional waste minimization technologies (molten salt oxidation, nitric acid recycle, americium extraction) that will significantly reduce ongoing waste generation rates and allow volume reduction of existing waste streams. Cost savings from reduction in waste volumes to be managed and disposed far exceed development and deployment costs in every case. Waste minimization is also important because it reduces occupational exposure to ionizing radiation, risks of transportation accidents, and transfer of burdens from current nuclear operations to future generations.

  15. The separation and recovery of hydrogen from the recycling gas in ammonia production by means of lanthanum-rich mischmetal nickel hydride beds

    International Nuclear Information System (INIS)

    Qidong, W.; Jing, W.; Changpin, C.; Weifang, L.

    1985-01-01

    The separation and recovery of hydrogen by means of a MlNi/sub 5/ (Ml: La-rich mischmetal) beds were studied. The influence of the impurity gas components (O/sub 2/, H/sub 2/O, N/sub 2/, Ar, CH/sub 4/ and NH/sub 3/ etc) on the hydrogen absorption capacity, hydriding and dehydriding kinetics and cycling ageing stability of the beds was investigated for both stagnant gases and continuously flowing gas streams. In small reactors, at first artificially made gas mixtures and finally the actual recycling gas from ammonia production were tested. In the presence of trace ammonia (<100ppm) in recycling gas stream, the efficiency of recovery amounted to 85 - 93% and the purity of the product hydrogen was around 99.9%. When ammonia amounted to 2.5%, the efficiency of recovery decreased to 81 - 86%. The hydrogen absorption capacity of the alloy bed remained unchanged after cycling 50 times, indicating the stability of the alloy satisfactory

  16. Advanced materials for solid state hydrogen storage: “Thermal engineering issues”

    International Nuclear Information System (INIS)

    Srinivasa Murthy, S.; Anil Kumar, E.

    2014-01-01

    Hydrogen has been widely recognized as the “Energy Carrier” of the future. Efficient, reliable, economical and safe storage and delivery of hydrogen form important aspects in achieving success of the “Hydrogen Economy”. Gravimetric and volumetric storage capacities become important when one considers portable and mobile applications of hydrogen. In the case of solid state hydrogen storage, the gas is reversibly embedded (by physisorption and/or chemisorption) in a solid matrix. A wide variety of materials such as intermetallics, physisorbents, complex hydrides/alanates, metal organic frameworks, etc. have been investigated as possible storage media. This paper discusses the feasibility of lithium– and sodium–aluminum hydrides with emphasis on their thermodynamic and thermo-physical properties. Drawbacks such as poor heat transfer characteristics and poor kinetics demand special attention to the thermal design of solid state storage devices. - Highlights: • Advanced materials suitable for solid state hydrogen storage are discussed. • Issues related to thermodynamic and thermo-physical properties of hydriding materials are brought out. • Hydriding and dehydriding behavior including sorption kinetics of complex hydrides with emphasis on alanates are explained

  17. Hydrogen compatibility of structural materials for energy storage and transmission applications. Semiannual report for period through October 1, 1976

    Energy Technology Data Exchange (ETDEWEB)

    Robinson, S.L. (comp.)

    1976-12-01

    Substantial support activities for Brookhaven National Laboratory (BNL) have been completed since the initiation of this program. The suitability of commercial alloys for containment of hydride-dehydride reactions have been assessed, and recommendations for materials selection based upon tensile and slow crack growth tests have been made. We have also prepared and installed in a test chamber at BNL a series of in-situ test specimens to be exposed to a cyclic iron-titanium hydride environment. Future BNL support activities will include welding/joining specification development and a post-mortem examination of the in-situ test specimens. Efforts are becoming more oriented to materials development and to the development of specifications for the use of structural steels in hydrogen environment. BNL's hydride storage program has been supported during the last six months by supplying 80 self-loaded tensile specimens for accelerated testing in an FeTiH/sub x/ test bed. A preliminary welding specification for containment of hydrogen in structural mild steels has been developed. Hydrogen permeation resistant coatings, applied by pyrolysis of silane, and by brush electroplating, have been developed. Environmentally assisted, cyclic fatigue in high-pressure hydrogen has been identified as a potential hazard to the integrity of flawed pressure vessels in materials where slow crack growth under constant load is not expected.

  18. Implementing waste minimization at an active plutonium processing facility: Successes and progress at technical area (TA) -55 of the Los Alamos National Laboratory

    International Nuclear Information System (INIS)

    Balkey, J.J.; Robinson, M.A.; Boak, J.

    1997-01-01

    The Los Alamos National Laboratory has ongoing national security missions that necessitate increased plutonium processing. The bulk of this activity occurs at Technical Area -55 (TA-55), the nations only operable plutonium facility. TA-55 has developed and demonstrated a number of technologies that significantly minimize waste generation in plutonium processing (supercritical CO 2 , Mg(OH) 2 precipitation, supercritical H 2 O oxidation, WAND), disposition of excess fissile materials (hydride-dehydride, electrolytic decontamination), disposition of historical waste inventories (salt distillation), and Decontamination ampersand Decommissioning (D ampersand D) of closed nuclear facilities (electrolytic decontamination). Furthermore, TA-55 is in the process of developing additional waste minimization technologies (molten salt oxidation, nitric acid recycle, americium extraction) that will significantly reduce ongoing waste generation rates and allow volume reduction of existing waste streams. Cost savings from reduction in waste volumes to be managed and disposed far exceed development and deployment costs in every case. Waste minimization is also important because it reduces occupational exposure to ionizing radiation, risks of transportation accidents, and transfer of burdens from current nuclear operations to future generations

  19. Synthesis and sintering of UN-UO{sub 2} fuel composites

    Energy Technology Data Exchange (ETDEWEB)

    Jaques, Brian J., E-mail: BrianJaques@BoiseState.edu [Department of Materials Science and Engineering, Boise State University, 1910 University Dr., Boise, ID 83725 (United States); Center for Advanced Energy Studies, 995 University Blvd., Idaho Falls, ID 83401 (United States); Watkins, Jennifer; Croteau, Joseph R.; Alanko, Gordon A. [Department of Materials Science and Engineering, Boise State University, 1910 University Dr., Boise, ID 83725 (United States); Center for Advanced Energy Studies, 995 University Blvd., Idaho Falls, ID 83401 (United States); Tyburska-Püschel, Beata [Department of Engineering Physics, University of Wisconsin–Madison, 1500 Engineering Dr., Madison, WI 53706 (United States); Meyer, Mitch [Idaho National Laboratory, Idaho Falls, ID 83415 (United States); Xu, Peng; Lahoda, Edward J. [Westinghouse Electric Company LLC, Pittsburgh, PA 15235 (United States); Butt, Darryl P., E-mail: DarrylButt@BoiseState.edu [Department of Materials Science and Engineering, Boise State University, 1910 University Dr., Boise, ID 83725 (United States); Center for Advanced Energy Studies, 995 University Blvd., Idaho Falls, ID 83401 (United States)

    2015-11-15

    The design and development of an economical, accident tolerant fuel (ATF) for use in the current light water reactor (LWR) fleet is highly desirable for the future of nuclear power. Uranium mononitride has been identified as an alternative fuel with higher uranium density and thermal conductivity when compared to the benchmark, UO{sub 2}, which could also provide significant economic benefits. However, UN by itself reacts with water at reactor operating temperatures. In order to reduce its reactivity, the addition of UO{sub 2} to UN has been suggested. In order to avoid carbon impurities, UN was synthesized from elemental uranium using a hydride-dehydride-nitride thermal synthesis route prior to mixing with up to 10 wt% UO{sub 2} in a planetary ball mill. UN and UN – UO{sub 2} composite pellets were sintered in Ar – (0–1 at%) N{sub 2} to study the effects of nitrogen concentration on the evolved phases and microstructure. UN and UN-UO{sub 2} composite pellets were also sintered in Ar – 100 ppm N{sub 2} to assess the effects of temperature (1700–2000 °C) on the final grain morphology and phase concentration.

  20. Hydrogen absorption kinetics in powdered V + 80 wt.% LaNi5 composite

    International Nuclear Information System (INIS)

    Kumar, Sanjay; Tirpude, Amit; Taxak, Manju; Krishnamurthy, Nagaiyar

    2013-01-01

    Highlights: •Vanadium prevents the pulverization of LaNi 5 . •H absorption capacity LaNi 5 –V composite is higher than LaNi 5 . •H absorption kinetics of LaNi 5 –V composite is relatively faster than V and LaNi 5 . •Fermi energy level of LaNi 5 –V composite lowered by vanadium addition. -- Abstract: The hydrogen absorption behavior of V + 80 wt.% LaNi 5 composite, LaNi 5 and V has been investigated. The LaNi 5 –V composite was prepared by high energy ball-milling technique using high pure vanadium and LaNi 5 powder. Lattice expansion of the composite has been observed in X-ray analysis which indicates the solid solution formation. Presence of free V and traces of V 2 O 5 phase were also observed in the composite. The hydrogen absorption capacity and absorption kinetics of the composite showed improvement as compared to LaNi 5 . The improved kinetics of the composite has been co-related to the change in lattices parameter, Fermi energy level and catalytic property of vanadium. Integrity of the composite has found to be effective even after 20 numbers of hydriding and dehydriding cycles due to the presence of vanadium

  1. Effect of TiH2 in the preparation of MMC Ti based with TiC reinforcement

    International Nuclear Information System (INIS)

    Peillon, N.; Fruhauf, J.B.; Gourdet, S.; Feraille, J.; Saunier, S.; Desrayaud, C.

    2015-01-01

    Highlights: • Using TiH 2 precursors promotes the MMC densification and microstructure homogeneity. • Clear description of the TiH 2 interest and limitations. • Coupling of TGA, TMA and EBSD analyses to investigate the sintering process of MMC. • Process parameters: granulometry, precursor composition, temperature and rate. - Abstract: Many studies were carried out on the elaboration Metal Matrix Composites (MMCs) and a wide variety of process is reported in the bibliography. For titanium based MMC, the basis material for these elaboration techniques mainly consists of atomized titanium powder. In this work a titanium hydride powder is used to elaborate Ti/TiC MMC. Although an additional dehydrogenation operation is required a significant decrease of the sintering temperature is expected with this basis powder. In this context, the behavior of titanium hydride powder mixed with 0, 10 and 20 vol.% TiC reinforcement is studied during densification by free sintering. The effects of particle size, temperature and rate of sintering reinforcement are discussed. The comparison of the TiH 2 process with Ti HDH (Hydride Dehydride) and atomized Ti mixture is made with 10 vol.% reinforcement. The results indicate that the sintering temperature is lowered and the final densities achieved are higher if the hydride is used. Interactions between dehydrogenation and sintering mechanisms clearly appear for the higher sintering temperature rate (10 °C/min) and need specific attention to prevent porosity nucleation through hydrogen entrapment

  2. Effects of various catalysts on hydrogen release and uptake characteristics of LiAlH{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Resan, Mirna; Hampton, Michael D.; Lomness, Janice K. [Department of Chemistry, University of Central Florida, 4000 Central Florida Boulevard, Orlando, FL 32816-2366 (United States); Slattery, Darlene K. [Florida Solar Energy Center, 1679 Clearlake Rd., Cocoa, FL 32922 (United States)

    2005-11-01

    The effects of various catalysts on the hydrogen release characteristics of LiAlH{sub 4} were studied. The catalysts were incorporated into the alanate by ball milling. The catalysts studied included elemental titanium, TiH{sub 2}, TiCl{sub 4}, TiCl{sub 3}, AlCl{sub 3}, FeCl{sub 3}, elemental iron, elemental nickel, elemental vanadium, and carbon black. Dehydriding/rehydriding properties were characterized by using differential scanning calorimetry coupled with pressure measurement and X-ray diffraction. The addition of TiCl{sub 3} and TiCl{sub 4} to LiAlH{sub 4} eliminated the first step of hydrogen evolution and significantly lowered decomposition temperature of the second step. Doping with elemental iron caused only a slight decrease in the amount of hydrogen released and did not eliminate the first step of hydrogen evolution. Ball milling in the absence of the catalyst was found to decrease the release temperature of hydrogen, while doping with elemental iron did not have any additional effect on the temperature of hydrogen release of LiAlH{sub 4}. (author)

  3. Hydriding of metallic thorium

    International Nuclear Information System (INIS)

    Miyake, Masanobu; Katsura, Masahiro; Matsuki, Yuichi; Uno, Masayoshi

    1983-01-01

    Powdered thorium is usually prepared through a combination of hydriding and dehydriding processes of metallic thorium in massive form, in which the hydriding process consists of two steps: the formation of ThH 2 , and the formation of Th 4 H 15 . However, little has yet been known as to on what stage of hydriding process the pulverization takes place. It is found in the present study that the formation of Th 4 H 15 by the reaction of ThH 2 with H 2 is responsible for pulverization. Temperature of 70 deg C adopted in this work for the reaction of formation Th 4 H 15 seems to be much more effective for production of powdered thorium than 200 - 300 deg C in the literature. The pressure-composition-temperature relationships for Th-H system are determined at 200, 300, 350, and 800 deg C. From these results, a tentative equilibrium phase diagram for the Th-H system is proposed, attention being focused on the two-phase region of ThH 2 and Th 4 H 15 . Pulverization process is discussed in terms of the tentative phase diagram. (author)

  4. Improvement of the performance of Mg-based alloy electrodes at ambient temperatures

    International Nuclear Information System (INIS)

    Liu, H.K.; Chen, J.; Sun, L.; Bradhurst, D.H.; Dou, S.X.

    1998-01-01

    Full text: Rechargeable batteries are finding increased application in modern communications, computers, and electric vehicles. The Nickel-Metal Hydride (Ni-MH) battery has the best comprehensive properties. It is known that the important step to increase the energy density of Ni-MH battery is to improve the negative (metal hydride) electrode properties. Of all the hydrogen storage alloys studied previously, (the best know alloys are LaNi 5 , Mg 2 Ni, Ti 2 Ni , TiNi and Zr 2 Ni), the intermetallic compound Mg 2 Ni has the highest theoretical hydrogen storage capacity. The Mg 2 Ni-based hydrogen storage alloy is a promising material for increasing the negative electrode capacity of Ni-MH batteries because this alloy is superior to the LaNi 5 -system or the Zr-based alloys in materials cost and hydrogen absorption capacity. A serious disadvantage, however, is that the reactions of most magnesium based alloys with hydrogen require relatively high temperature (>300 deg C) and pressure (up to 10 atm) due to the slowness of the hydriding/dehydriding reactions. In this paper it is shown that with a combination of modifications to the alloy composition and methods of electrode preparation, magnesium-based alloys can be made into electrodes which will not only be useful at ambient temperatures but will have a useful cycle life and extremely high capacity

  5. Thermal to Electric Energy Conversion for Cyclic Heat Loads

    Science.gov (United States)

    Whitehead, Benjamin E.

    exothermic, and dehydriding is endothermic, we can use the reaction to control temperature and store or release energy as desired. Connecting the liberated hydrogen gas to a hydrogen/air or hydrogen/oxygen fuel cell can then generate useful electrical power. A fuel cell operates by flowing hydrogen and oxygen over a membrane that only allows protons through. This process creates a voltage through the separation of the negatively charged electrons and positively charged water. Typical fuel cells operate at 30-40% efficiency with research aiming to increase that number to 65% with solid oxide fuel cells. [3]. In this thesis, I develop several models to size metal hydride systems, identify the critical design parameters of a metal hydride system, and predict hydrogen production for a given heat source. The first model consists of a lumped parameter treatment that analyzes how the effects of varying metal hydrides and heat source values change the dehydriding process. The second model uses COMSOLRTM Multiphysics to create a higher fidelity simulation of the heat transfer within a metal hydride bed by calculating the spatial heat transfer as well as the porous nature of the system. The Comsol model shows that thermal conductivity is the highest sensitivity parameter of those studied, and therefore should be the primary focus for system design. The model also shows that the efficiency of the system is relatively independent of the duty cycle of the heat source.

  6. Analyses on the U-Mo/Al Chemical Interaction and the Effects of Diffusion Barrier Coatings

    Energy Technology Data Exchange (ETDEWEB)

    Ryu, Ho Jin; Kim, Woo Jeong; Cho, Woo Hyung; Jeong, Yong Jin; Lee, Yoon Sang; Park, Jong Man; Kim, Chang Kyu [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2012-05-15

    While many HEU-fueled research reactors have been converted by adopting LEU U{sub 3}Si{sub 2} fuel in harmony with the Reduced Enrichment for Research and Test Reactors (RERTR) program, some high performance research reactors still need the development of advanced fuels with higher uranium densities. Currently, gamma-phase U-Mo alloys are considered promising candidates to be used as high uranium density fuel for the high performance reactors. For the production of UMo alloy powder, the centrifugal atomization technology developed by KAERI has been considered the most promising way because of high yield production and excellent powder quality when compared with other possible methods such as grinding, machining or hydriding-dehydriding. However, severe pore formation associated with an extensive interaction between the U-Mo and Al matrix, although the irradiation performance of U-Mo itself showed most stable, delay the fuel qualification of UMo fuel for high performance research reactors. Because the reaction products, i.e. uranium aluminides (UAlx), is less dense than the mixed reactants, the volume of the fuel meat increases after formation of interaction layer(IL). In addition to the impact on the swelling performance, the reaction layers between the U-Mo and Al matrix induces a degradation of the thermal conductivities of the U-Mo/Al dispersion fuels. The chemical interaction between the U-Mo and Al matrix are analyzed in this study to find remedies to reduce the growth of the interaction layers during irradiation. In addition, various coating technologies for the formation of diffusion barriers on U-Mo particles are proposed as a result of the analyses

  7. Enhanced Hydrogen Storage Kinetics of Nanocrystalline and Amorphous Mg₂Ni-type Alloy by Melt Spinning.

    Science.gov (United States)

    Zhang, Yang-Huan; Li, Bao-Wei; Ren, Hui-Ping; Li, Xia; Qi, Yan; Zhao, Dong-Liang

    2011-01-18

    Mg₂Ni-type Mg₂Ni 1-x Co x (x = 0, 0.1, 0.2, 0.3, 0.4) alloys were fabricated by melt spinning technique. The structures of the as-spun alloys were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The hydrogen absorption and desorption kinetics of the alloys were measured by an automatically controlled Sieverts apparatus. The electrochemical hydrogen storage kinetics of the as-spun alloys was tested by an automatic galvanostatic system. The results show that the as-spun (x = 0.1) alloy exhibits a typical nanocrystalline structure, while the as-spun (x = 0.4) alloy displays a nanocrystalline and amorphous structure, confirming that the substitution of Co for Ni notably intensifies the glass forming ability of the Mg₂Ni-type alloy. The melt spinning treatment notably improves the hydriding and dehydriding kinetics as well as the high rate discharge ability (HRD) of the alloys. With an increase in the spinning rate from 0 (as-cast is defined as spinning rate of 0 m/s) to 30 m/s, the hydrogen absorption saturation ratio () of the (x = 0.4) alloy increases from 77.1 to 93.5%, the hydrogen desorption ratio () from 54.5 to 70.2%, the hydrogen diffusion coefficient (D) from 0.75 × 10 - 11 to 3.88 × 10 - 11 cm²/s and the limiting current density I L from 150.9 to 887.4 mA/g.

  8. Enhanced Hydrogen Storage Kinetics of Nanocrystalline and Amorphous Mg2Ni-type Alloy by Melt Spinning

    Directory of Open Access Journals (Sweden)

    Hui-Ping Ren

    2011-01-01

    Full Text Available Mg2Ni-type Mg2Ni1−xCox (x = 0, 0.1, 0.2, 0.3, 0.4 alloys were fabricated by melt spinning technique. The structures of the as-spun alloys were characterized by X-ray diffraction (XRD and transmission electron microscopy (TEM. The hydrogen absorption and desorption kinetics of the alloys were measured by an automatically controlled Sieverts apparatus. The electrochemical hydrogen storage kinetics of the as-spun alloys was tested by an automatic galvanostatic system. The results show that the as-spun (x = 0.1 alloy exhibits a typical nanocrystalline structure, while the as-spun (x = 0.4 alloy displays a nanocrystalline and amorphous structure, confirming that the substitution of Co for Ni notably intensifies the glass forming ability of the Mg2Ni-type alloy. The melt spinning treatment notably improves the hydriding and dehydriding kinetics as well as the high rate discharge ability (HRD of the alloys. With an increase in the spinning rate from 0 (as-cast is defined as spinning rate of 0 m/s to 30 m/s, the hydrogen absorption saturation ratio ( of the (x = 0.4 alloy increases from 77.1 to 93.5%, the hydrogen desorption ratio ( from 54.5 to 70.2%, the hydrogen diffusion coefficient (D from 0.75 × 10−11 to 3.88 × 10−11 cm2/s and the limiting current density IL from 150.9 to 887.4 mA/g.

  9. Compaction of Ti–6Al–4V powder using high velocity compaction technique

    International Nuclear Information System (INIS)

    Khan, Dil Faraz; Yin, Haiqing; Li, He; Qu, Xuanhui; Khan, Matiullah; Ali, Shujaat; Iqbal, M. Zubair

    2013-01-01

    Highlights: • We compacted Ti–6Al–4V powder by HVC technique. • As impact force rises up, the green density of the compacts increases gradually. • At impact force 1.857 kN relative sintered density of the compacts reaches 99.88%. • Spring back of the green compact’s decreases gradually with increasing impact force. • Mechanical properties of the samples increases with increasing impact force. - Abstract: High velocity compaction technique was applied to the compaction of pre-alloyed, hydride–dehydride Ti–6Al–4V powder. The powder was pressed in single stroke with a compaction speed of 7.10–8.70 ms −1 . When the speed was 8.70 ms −1 , the relative density of the compacts reaches up to 85.89% with a green density of 3.831 g cm −3 . The green samples were sintered at 1300 °C in Ar-gas atmosphere. Scanning electron microscope (SEM) was used to examine the surface of the sintered samples. Density and mechanical properties such as Vickers micro hardness and bending strength of the powder samples were investigated. Experimental results indicated that with the increase in impact force, the density and mechanical properties of the compacts increased. The sintered compacts exhibited a maximum relative density of 99.88% with a sintered density of 4.415 g cm −3 , hardness of 364–483 HV and the bending strength in the range of 103–126.78 MPa. The springback of the compacts decreased with increasing impact force

  10. Directed light fabrication of refractory metals and alloys

    International Nuclear Information System (INIS)

    Fonseca, J.C.; Lewis, G.K.; Dickerson, P.G.; Nemec, R.B.

    1999-01-01

    This report covers deposition of refractory pure metals and alloys using the Directed Light Fabrication (DLF) process and represents progress in depositing these materials through September 1998. In extending the DLF process technology to refractory metals for producing fully dense, structurally sound deposits, several problems have become evident. (1) Control of porosity in DLF-deposited refractory metal is difficult because of gases, apparently present in commercially purchased refractory metal powder starting materials. (2) The radiant heat from the molten pool during deposition melts the DLF powder feed nozzle. (3) The high reflectivity of molten refractory metals, at the Nd-YAG laser wavelength (1.06microm), produces damaging back reflections to the optical train and fiber optic delivery system that can terminate DLF processing. (4) The current limits on the maximum available laser power to prevent back reflection damage limit the parameter range available for densification of refractory metals. The work to date concentrated on niobium, W-25Re, and spherodized tungsten. Niobium samples, made from hydride-dehydride powder, had minimal gas porosity and the deposition parameters were optimized; however, test plates were not made at this time. W-25Re samples, containing sodium and potassium from a precipitation process, were made and porosity was a problem for all samples although minimized with some process parameters. Deposits made from potassium reduced tungsten that was plasma spherodized were made with minimized porosity. Results of this work indicate that further gas analysis of starting powders and de-gassing of starting powders and/or gas removal during deposition of refractory metals is required

  11. Directed light fabrication of refractory metals and alloys

    International Nuclear Information System (INIS)

    Fonseca, J.C.; Lewis, G.K.; Dickerson, P.G.; Nemec, R.B.

    1999-01-01

    This report covers work performed under Order No. FA0000020 AN Contract DE-AC12-76SN00052 for deposition of refractory pure metals and alloys using the Directed Light Fabrication (DLF) process and represents the progress in depositing these materials through September 1998. In extending the DLF process technology to refractory metals for producing fully dense, structurally sound deposits, several problems have become evident. 1. Control of porosity in DLF-deposited refractory metal is difficult because of gases, apparently present in commercially purchased refractory metal powder starting materials. 2. The radiant heat from the molten pool during deposition melts the DLF powder feed nozzle. 3. The high reflectivity of molten refractory metals, at the Nd-YAG laser wavelength (1.06microm), produces damaging back reflections to the optical train and fiber optic delivery system that can terminate DLF processing. 4. The current limits on the maximum available laser power to prevent back reflection damage limit the parameter range available for densification of refractory metals. The work to date concentrated on niobium, W-25Re, and spherodized tungsten. Niobium samples, made from hydride-dehydride powder, had minimal gas porosity and the deposition parameters were optimized; however, test plates were not made at this time. W-25Re samples, containing sodium and potassium from a precipitation process, were made and porosity was a problem for all samples although minimized with some process parameters. Deposits made from potassium reduced tungsten that was plasma spherodized were made with minimized porosity. Results of this work indicate that further gas analysis of starting powders and de-gassing of starting powders and/or gas removal during deposition of refractory metals is required

  12. Effect of MoS2 on hydrogenation storage properties of LiBH4

    International Nuclear Information System (INIS)

    Liang, Dan; Han, Shumin; Wang, Jiasheng; Zhang, Wei; Zhao, Xin; Zhao, Ziyang

    2014-01-01

    The hydrogen storage properties of LiBH 4 ball milled with 20 wt% MoS 2 have been investigated. It shows that the LiBH 4 doped with MoS 2 exhibits favorable hydrogenation and dehydrogenation properties in terms of decomposition temperature and hydriding/dehydriding reversibility. The sample with MoS 2 starts to release hydrogen at 230 °C and has a decrease of 80 °C in contrast with pristine LiBH 4 . Furthermore, for the second cycle, the LiBH 4 with MoS 2 maintains a reversible hydrogen storage capacity of about 8.0 wt% which is almost identical with the first cycle under 5 MPa at 550 °C. Analyzed by the XRD and the FTIR results, LiBH 4 can be regenerated after re-hydrogenation under a relatively mild condition by adding MoS 2 . The improvement of the hydrogenation and dehydrogenation properties mainly results from the formation of Li 2 S and MoB 2 during ball milling. -- Graphical abstract: Hydrogen absorption curves of LiBH 4 doped with MoS 2 for five cycles at 400 °C. Highlights: • The hydrogen absorption capacity is nearly the same for 5 cycles at 400 °C. • The sample with MoS 2 starts to release hydrogen at 230 °C. • The coexistence of MoB 2 and Li 2 S catalyzes the decomposition of LiBH 4

  13. Re-examination of the neptunium-hydrogen system

    International Nuclear Information System (INIS)

    Ward, J.W.; Bartscher, W.; Rebizant, J.

    1986-01-01

    New P-C-T studies have been made on the Np + H system, using ultrapure double-electrorefined metal. Measurements were carried out over six orders of magnitude in pressure, from 0.0005 to 70 bar. The solubility of hydrogen was found to be very low. Metal-dihydride plateaus were flat, the two-phase boundary extremely sharp; this occurred at the unusual value H/Np approx. = 2.13. The dihydride lattice expanded upon addition of hydrogen, also in contrast to other trivalent rare-earth and actinide hydrides. A rather narrow cubic/hexagonal two-phase region was found (only on dehydriding), together with an even narrower hexagonal phase region. The effect of the beta-gamma transition at 576 0 C could be seen both in the curvature of the phase boundary and the partial molal enthalpy values. Entropies of formation were found to be nearly constant. The data below 576 0 C can be described by the equation ln P(bar) = 13.297 - 13233/T(K), giving values, adjusted for the reaction 0.93 Np + H 2 = 0.93 NpH/sub 2.13/: ΔH/sub f/(NpH/sub 2.13/) = 118.3 kJ/mol (28.27 kcal/mol), and ΔS/sub f/(NpH/sub 2.13/) = 118.4 J/mol-K (28.3 cal/mol/-K). Integral heats and entropies are calculated for the entire system, and the unusual phase behavior is discussed in terms of the electronic structure

  14. Study on the microstructure of recycled zircaloy by X-ray diffraction line profile analysis

    International Nuclear Information System (INIS)

    Ichikawa, Rodrigo U.; Pereira, Luiz A.T.; Imakuma, Kengo; Martinez, Luis G.; Turrillas, Xavier

    2013-01-01

    In the fabrication of nuclear fuel elements parts, Zircaloy machining chips are generated and, as this material is high-valued and controlled, its recycling presents high interest not only in economic aspects but also for environmental reasons and due to its strategic role in nuclear technology. Two processes for the recovery of these Zircaloy chips are being studied at IPEN-CNEN/SP. One of the processes is by conventional remelting of the material in a VAR (Vacuum Arc Remelting) furnace for producing solid ingots. Concurrently it is being studied an alternative process, by powder metallurgy methods, by which the chips are hydrided in order to become brittle and be grinded. The resulting ground powder is then compacted and finally vacuum-dehydrided and sintered in one step to form solid pieces. The VAR-remelted samples were also submitted to heat treatments in order to refine their microstructures, resulting in three different samples named 'as cast', 'annealed' and 'tempered'. The microstructures resulting from both processes and also from heat treatments were studied by metallography and X-ray diffraction (XRD). In this work, results of a XRD study are presented applying X-ray diffraction Line Profile Analysis (XLPA) methods in order to determine the mean crystallite sizes and the RMS microstrains on these samples. Additionally, a study for verify the influence of different standard materials used for the correction of the instrumental breadth in the XLPA was developed. The XLPA results show the influence of the processes and also of heat treatments on mean crystallite sizes and microstrains of the samples and were compared to their metallographic study and hardness. (author)

  15. Dual-tuning effects of In, Al, and Ti on the thermodynamics and kinetics of Mg85In5Al5Ti5 alloy synthesized by plasma milling

    International Nuclear Information System (INIS)

    Cao, Zhijie; Ouyang, Liuzhang; Wu, Yuyu; Wang, Hui; Liu, Jiangwen; Fang, Fang; Sun, Dalin; Zhang, Qingan; Zhu, Min

    2015-01-01

    Highlights: • Mg 85 In 5 Al 5 Ti 5 alloy catalyzed with in-situ formed MgF 2 was prepared by P-milling. • Reaction mechanism of Mg 85 In 5 Al 5 Ti 5 alloy was presented. • Further destabilization of Mg was realized (65.2 kJ/mol H 2 ). • Dual tuning of the thermodynamic and kinetic properties of MgH 2 was realized. - Abstract: The dehydrogenation enthalpy change of MgH 2 by reversibly forming an Mg 0.95 In 0.05 solid solution offers a new method for tuning the thermodynamics of Mg-based alloys. In order to further lower the stability of MgH 2 , Al has been introduced into Mg(In) solid solution. At the same time, to solve the problem of sluggish kinetic properties of Mg–In solid–solution systems and to lower the dehydrogenation activation energy, Ti has also been added. It has been demonstrated that the Mg 85 In 5 Al 5 Ti 5 alloy synthesized by plasma milling (P-milling) shows both enhanced dehydriding thermodynamics and kinetics. This technique could be used to synthesize Mg(In, Al) ternary solid solution incorporating the Ti catalyst in only one step, making it much more efficient than the two-step method. Compared with Mg-based solid solutions, the addition of Ti and in-situ synthesized MgF 2 improved the kinetics and the introduction of In as well as Al imparted enhanced thermodynamics to the Mg 85 In 5 Al 5 Ti 5 system. The dehydrogenation enthalpy change and activation energy were lowered to 65.2 kJ/(mol H 2 ) and 125.2 kJ/mol, respectively, for the Mg 85 In 5 Al 5 Ti 5 alloy

  16. The Rocky Flats Decontamination and Decommissioning (D and D) Challenge

    International Nuclear Information System (INIS)

    Parker, A.M.; Mathis, B.W.; Stevens, J.L.

    1999-01-01

    At the Rocky Flats Environmental Technology Site (RFETS), the D and D task is enormous. Tons of plutonium has been processed over the years in approximately 1,000 gloveboxes, This represents nearly half of the gloveboxes in the DOE complex. In addition, more than a thousand tanks of various designs, with miles of associated piping, supported the processes. A wide variety of operations were performed at RFETS, including aqueous processing, pyrophoric processing, hydriding and dehydriding, metal casting, and machining of plutonium. Various materials have been handled at the facility, including plutonium, uranium, americium, tantalum, beryllium, chloride salts, and various acids and solvents. Significant amounts of plutonium residues remain in inaccessible equipment in the facilities, which create criticality safety issues. Some of the plutonium has been at RFETS for many years, and there is significant in-growth of americium, a decay product that emits gamma radiation, which potentially increases exposure to the workers. The size reduction portion of the D and D will be difficult and costly. The gloveboxes and tanks are constructed of stainless steel, frequently with lead shielding or double walls that hold water for neutron shielding. Window mountings, glove port rings, site gages, bolted flanges, and various penetrations reinforce the walls. Tanks may be filled with berated glass rings for criticality control, or double walled to hold the process fluid in the space between walls. The gloveboxes and tanks are generally tall enough to require workers to stand on scaffolding or platforms to perform D and D. Gloveboxes and tanks were individually constructed over a span of many years with evolving design specifications; therefore, most gloveboxes are unique and few tank designs are duplicated in more than pairs. This paper describes the cultural transition and technical approaches taken for D and D at RFETS to achieve 2006 closure. Specific emphasis is placed on

  17. Experimental study on uranium alloys for hydrogen storage

    International Nuclear Information System (INIS)

    Deaconu, M.; Meleg, T.; Dinu, A.; Mihalache, M.; Ciuca, I.; Abrudeanu, M.

    2013-01-01

    The heaviest isotope of hydrogen is one of critically important elements in the field of fusion reactor technology. Conventionally, uranium metal is used for the storage of heavier isotopes of hydrogen (D and T). Under appropriate conditions, uranium absorbs hydrogen to form a stable UH 3 compound when exposed to molecular hydrogen at the temperature range of 300-500 O C at varied operating pressure below one atmosphere. However, hydriding-dehydriding on pure uranium disintegrates the specimen into fine powder. The powder is highly pyrophoric and has low heat conductivity, which makes it difficult to control the temperature, and has a high possibility of contamination Due to the powdering effect as hydrogen in uranium, alloying uranium with other metal looks promising for the use of hydrogen storage materials. This paper has the aim to study the hydriding properties of uranium alloys, including U-Ti U-Mo and U-Ni. The uranium alloys specimens were prepared by melting the constituent elements by means of simultaneous measurements of thermo-gravimetric and differential thermal analyses (TGA-DTA) and studied in as cast condition as hydrogen storage materials. Then samples were thermally treated under constant flow of hydrogen, at various temperatures between 573-973 0 K. The structural and absorption properties of the products obtained were examined by thermo-gravimetric analysis (TG), X-ray diffraction (XRD) and scanning electron microscopy (SEM). They slowly reacted with hydrogen to form the ternary hydride and the hydrogenated samples mainly consisted of the pursued ternary hydride bat contained also U or UO 2 and some transient phase. (authors)

  18. Synthesis of Zn(BH{sub 4}){sub 2} and Gas Absorption and Release Characteristics of Zn(BH{sub 4}){sub 2}, Ni, or Ti-Added MgH{sub 2}–Based Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Kwak, Young Jun; Lee, Seong Ho; Kwon, Sung Nam; Park Il Woo; Song, Myoung Youp [Chonbuk National University, Jeonju (Korea, Republic of)

    2015-07-15

    A sample [named Zn(BH{sub 4}){sub 2}(+NaCl)] was synthesized by milling ZnCl{sub 2} and NaBH{sub 4} at 400 rpm under argon gas for 2 h. And Zn(BH{sub 4}){sub 2}(+NaCl)+MgH{sub 2} sample was prepared by milling MgH{sub 2} in a planetary ball mill and mixing with the Zn(BH{sub 4}){sub 2}(+NaCl) synthesized by milling for 4 h in a mortar with a pestle. Then the gas-release characteristics of the two samples were investrigated. Analyses of XRD patterns and FT-IR spectra, as well as TGA, DTA, and SEM observations, were also performed. After heating the samples to 400 ℃, the weight losses of Zn(BH{sub 4}){sub 2}(+NaCl) and Zn(BH{sub 4}){sub 2}(+NaCl)+MgH{sub 2} were 11.2 and 8.2 wt%, respectively, with respect to the sample weight. The DTA results for the two samples showed a decomposition peak for Zn(BH{sub 4}){sub 2} at about 61 ℃. The DTA result of Zn(BH{sub 4}){sub 2}(+NaCl) + MgH{sub 2} showed a decomposition peak for MgH{sub 2} at about 374 ℃. A sample of Zn(BH{sub 4}){sub 2}(+NaCl)+MgH{sub 2} to which Ni, and Ti were added, with a composition of 90 wt% MgH{sub 2}-5 wt% Zn(BH{sub 4}){sub 2}(+NaCl)-2.5 wt% Ni-2.5 wt% Ti, in which a large amount of MgH2 is contained in order to make a large quantity of hydrogen be absorbed and released reversibly, was also prepared. The experimental results showed that addition of Zn(BH{sub 4}){sub 2}(+NaCl), Ni, or Ti increased the dehydriding rate of MgH{sub 2}, while decreased its initial hydriding rate.

  19. Effect of multi-wall carbon nanotubes supported nano-nickel and TiF{sub 3} addition on hydrogen storage properties of magnesium hydride

    Energy Technology Data Exchange (ETDEWEB)

    Su, Wei; Zhu, Yunfeng, E-mail: yfzhu@njtech.edu.cn; Zhang, Jiguang; Liu, Yana; Yang, Yang; Mao, Qifeng; Li, Liquan

    2016-06-05

    Multi-wall carbon nanotubes supported nano-nickel (Ni/MWCNTs) with superior catalytic effects was introduced to magnesium hydride by the process of hydriding combustion synthesis (HCS) and mechanical milling (MM). The effect of different Ni/MWCNTs contents (5 wt.%, 10 wt.%, 15 wt.%, 20 wt.%) on the hydrogenation and dehydrogenation properties of the composite was investigated systematically. It is revealed that Mg{sub 85}-(Ni/MWCNTs){sub 15} composite shows the best comprehensive hydrogen storage properties, which absorbs 5.68 wt.% hydrogen within 100 s at 373 K and releases 4.31 wt.% hydrogen within 1800 s at 523 K under initial hydrogen pressures of 3.0 and 0.005 MPa, respectively. The in situ formed nano-Mg{sub 2}Ni and MWCNTs have excellent catalytic effect on the hydrogenation and dehydrogenation performances of MgH{sub 2}. To further improve the hydrogen absorption/desorption properties, TiF{sub 3} was added to the Mg–Ni/MWCNTs system. The result shows that TiF{sub 3} addition has little influence on the thermodynamic performance, but affects greatly the kinetic properties. The Mg{sub 85}-(Ni/MWCNTs){sub 15}-TiF{sub 3} composite exhibits an appreciably enhanced hydrogen desorption performance at low temperature, and the hydrogen desorption capacity within 1800 s at 473 K for the TiF{sub 3}-added composite is approximately four times the capacity of Mg{sub 85}-(Ni/MWCNTs){sub 15} under the same condition. The catalytic effects during hydrogenation and dehydrogenation have been discussed in the study. - Highlights: • The nanosized Ni/MWCNTs catalyst was successfully prepared. • Ni/MWCNTs shows superior catalytic effect on H absorption/desorption of Mg. • Mg{sub 85}-(Ni/MWCNTs){sub 15} composite shows the best hydrogen storage properties. • Ni/MWCNTs coupling with TiF{sub 3} improves the hydriding/dehydriding properties largely.

  20. Hydrogen absorption in Mg1.95Ti0.05Ni0.95Cu0.05 alloy prepared with mechanical alloying and thermal treatment; Absorcion de hidrogeno en la aleacion Mg1.95Ti0.05Ni0.95Cu0.05 preparada por aleado mecanico y tratamiento termico

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, Juan Bonifacio; Urena Nunez, Fernando [Instituto Nacional de Investigaciones Nucleares, Ocoyoacac, Estado de Mexico (Mexico)]. E-mail: juan.bonifacio@inin.gob.mx

    2009-09-15

    This work presents hydrogen absorption in quaternary alloy Mg1.95Ti0.05Ni0.95Cu0.05 obtained by the mechanical alloying method, followed by thermal treatment in ultra-high pure argon atmosphere. The composition of the phases, microstructure and morphology of ground powders and with thermal treatment were characterized by DRX, SEM/EDS and TEM. After 20 hours of mechanical grinding and recooked at 300 degrees Celsius/1h in argon atmosphere, the quaternary alloy has a Mg{sub 2}Ni crystalline hexagonal structure with a crystallite size under 10 nm. The absorption measurements were performed under a pressure of 0.2 to 1.2 MPa at a temperature of 200 degrees Celsius in a micro-reactor. The quantification of absorption-desorption of hydrogen in the intermetallic was conducted in a TGA-DSC simultaneous calorimeter. Metallic hydride-dehydride powder was characterized with SEM and XRD. [Spanish] En este trabajo se presenta la absorcion de hidrogeno en la aleacion cuaternaria Mg1.95Ti0.05Ni0.95Cu0.05 obtenida por el metodo de aleado mecanico, seguida de tratamiento termico en atmosfera de argon de ultra alta pureza. La composicion de las fases, microestructura y morfologia de los polvos molidos y con tratamiento termico fue caracterizada por DRX, SEM/EDS y TEM. Despues de 20 h de molienda mecanica con recocido a 300 grados Celsios/1h en atmosfera de argon, la aleacion cuaternaria tiene una estructura cristalina hexagonal Mg{sub 2}Ni con tamano de cristalito menor a 10 nm. Las mediciones de absorcion fueron realizadas bajo una presion de 0.2 a 1.2 MPa a una temperatura de 200 grados Celsios en un micro-reactor. La cuantificacion de absorcion-desorcion de hidrogeno en el intermetalico se realizo en un calorimetro simultaneo TGA-DSC. Se determino que la cantidad maxima absorbida de hidrogeno en la aleacion cuaternaria fue de 3.24% en peso cuando la presion fue de 0.8 MPa a dicha temperatura. Polvos metalicos hidrurados-deshidrurados se caracterizaron por SEM y XRD.

  1. Hydrogen sorption properties of ball-milled Mg-C nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Spassov, Tony; Zlatanova, Zlatina; Spassova, Maya; Todorova, Stanislava [Faculty of Chemistry, University of Sofia ' ' St.Kl.Ohridski' ' , 1 James Bourchier str. 1164 Sofia (Bulgaria)

    2010-10-15

    MgH{sub 2} 75 at.%-C 25 at.% composites are synthesized by ball milling using different kinds of carbon additives: carbon black (CB), nanodiamonds (ND) and amorphous carbon soot (AC). X-ray diffraction analysis showed that the MgH{sub 2} phase in the as-obtained composite powders is nanocrystalline (80-100 nm). The SEM observations revealed that the samples consist of 5-15 {mu}m MgH{sub 2} particles, surrounded and in some cases coated by carbon flakes. The composite containing nanodiamonds revealed strong decrease of the MgH{sub 2} decomposition temperature with more than 100 C, compared to ball-milled pure MgH{sub 2}. Important issue of the present study is also the low temperature hydriding of the ball-milled Mg-C nanocomposites, investigated by high-pressure DSC. The process starts at about 200 C for all materials studied, but the hydriding mechanism looks different for the composites with different kinds of carbon additives. Whereas for Mg-carbon black it takes place in a relatively narrow temperature range, expressed by a single exothermic peak (200-300 C) for the other two composites the hydriding is a multi-step process, featured by two overlapped exothermic peaks for Mg-nanodiamonds and by two well separated exothermic effects (at about 300 C and 400 C) for Mg-amorphous carbon soot. The observed difference in the hydriding behavior of the Mg-C composites is attributed to the different kind of carbon component, which is supposed to play a catalytic role as well as protects magnesium from oxidation. The incorporation of carbon into the MgH{sub 2} particles results in the formation of high density of defects (dislocations and grain boundaries), which is supposed to be among the most possible reasons for the decreased hydride decomposition temperature. The Mg-C nanocomposites show reproducible hydriding/dehydriding behavior (thermodynamics and kinetics) during multiple cycling. Among the composites in the present study ''Mg-carbon black

  2. Powder Metallurgy of Uranium Alloy Fuels for TRU-Burning Reactors Final Technical Report

    Energy Technology Data Exchange (ETDEWEB)

    McDeavitt, Sean M

    2011-04-29

    outlining the beginning of the materials processing setup. Also included within this section is a thesis proposal by Jeff Hausaman. Appendix C contains the public papers and presentations introduced at the 2010 American Nuclear Society Winter Meeting. Appendix A—MSNE theses of David Garnetti and Grant Helmreich and proposal by Jeff Hausaman A.1 December 2009 Thesis by David Garnetti entitled “Uranium Powder Production Via Hydride Formation and Alpha Phase Sintering of Uranium and Uranium-Zirconium Alloys for Advanced Nuclear Fuel Applications” A.2 September 2009 Presentation by David Garnetti (same title as document in Appendix B.1) A.3 December 2010 Thesis by Grant Helmreich entitled “Characterization of Alpha-Phase Sintering of Uranium and Uranium-Zirconium Alloys for Advanced Nuclear Fuel Applications” A.4 October 2010 Presentation by Grant Helmreich (same title as document in Appendix B.3) A.5 Thesis Proposal by Jeffrey Hausaman entitled “Hot Extrusion of Alpha Phase Uranium-Zirconium Alloys for TRU Burning Fast Reactors” Appendix B—External presentations introduced at the 2010 ANS Winter Meeting B.1 J.S. Hausaman, D.J. Garnetti, and S.M. McDeavitt, “Powder Metallurgy of Alpha Phase Uranium Alloys for TRU Burning Fast Reactors,” Proceedings of 2010 ANS Winter Meeting, Las Vegas, Nevada, USA, November 7-10, 2010 B.2 PowerPoint Presentation Slides from C.1 B.3 G.W. Helmreich, W.J. Sames, D.J. Garnetti, and S.M. McDeavitt, “Uranium Powder Production Using a Hydride-Dehydride Process,” Proceedings of 2010 ANS Winter Meeting, Las Vegas, Nevada, USA, November 7-10, 2010 B.4. PowerPoint Presentation Slides from C.3 B.5 Poster Presentation from C.3 Appendix C—Fuel cycle research and development undergraduate materials and poster presentation C.1 Poster entitled “Characterization of Alpha-Phase Sintering of Uranium and Uranium-Zirconium Alloys” presented at the Fuel Cycle Technologies Program Annual Meeting C.2 April 2011 Honors Undergraduate Thesis

  3. Powder Metallurgy of Uranium Alloy Fuels for TRU-Burning Reactors Final Technical Report

    International Nuclear Information System (INIS)

    McDeavitt, Sean M.

    2011-01-01

    beginning of the materials processing setup. Also included within this section is a thesis proposal by Jeff Hausaman. Appendix C contains the public papers and presentations introduced at the 2010 American Nuclear Society Winter Meeting. Appendix A - MSNE theses of David Garnetti and Grant Helmreich and proposal by Jeff Hausaman A.1 December 2009 Thesis by David Garnetti entitled 'Uranium Powder Production Via Hydride Formation and Alpha Phase Sintering of Uranium and Uranium-Zirconium Alloys for Advanced Nuclear Fuel Applications' A.2 September 2009 Presentation by David Garnetti (same title as document in Appendix B.1) A.3 December 2010 Thesis by Grant Helmreich entitled 'Characterization of Alpha-Phase Sintering of Uranium and Uranium-Zirconium Alloys for Advanced Nuclear Fuel Applications' A.4 October 2010 Presentation by Grant Helmreich (same title as document in Appendix B.3) A.5 Thesis Proposal by Jeffrey Hausaman entitled 'Hot Extrusion of Alpha Phase Uranium-Zirconium Alloys for TRU Burning Fast Reactors' Appendix B - External presentations introduced at the 2010 ANS Winter Meeting B.1 J.S. Hausaman, D.J. Garnetti, and S.M. McDeavitt, 'Powder Metallurgy of Alpha Phase Uranium Alloys for TRU Burning Fast Reactors,' Proceedings of 2010 ANS Winter Meeting, Las Vegas, Nevada, USA, November 7-10, 2010 B.2 PowerPoint Presentation Slides from C.1 B.3 G.W. Helmreich, W.J. Sames, D.J. Garnetti, and S.M. McDeavitt, 'Uranium Powder Production Using a Hydride-Dehydride Process,' Proceedings of 2010 ANS Winter Meeting, Las Vegas, Nevada, USA, November 7-10, 2010 B.4. PowerPoint Presentation Slides from C.3 B.5 Poster Presentation from C.3 Appendix C - Fuel cycle research and development undergraduate materials and poster presentation C.1 Poster entitled 'Characterization of Alpha-Phase Sintering of Uranium and Uranium-Zirconium Alloys' presented at the Fuel Cycle Technologies Program Annual Meeting C.2 April 2011 Honors Undergraduate Thesis by William Sames, Research Fellow

  4. Part I: Structural Characterization of Doped Nanostructured Magnesium: Understanding Disorder for Enhanced Hydrogen Absorption Kinetics Part II: Synthesis, Film Deposition, and Characterization of Quaternary Metal Chalcogenide Nanocrystals for Photovoltaic Applications

    Science.gov (United States)

    Braun, Max B.

    The production, storage, and subsequent consumption of energy are at the foundation of all human activity and livelihood. The theme of this dissertation is the pursuit of fundamental understanding of the chemistry of materials that are used for energy production and storage. A strong emphasis is placed on a synthetic foundation that allows for systematic investigation into the fundamental chemistry that controls the applicable properties of the materials of interest. This dissertation is written in the "journals format" style--which is accepted by the Graduate School at Colorado State University--and is based on one peer-reviewed publication that has appeared in Chemistry of Materials as well as two manuscripts to be submitted, one to The Journal of Physical Chemistry C, and one to ACS Applied Materials and Interfaces. In order to create a context for these publications, Chapters 1 and 3 provide an overview of the motivations for the projects, and then continue to detail the initial synthetic investigations and considerations for the two projects. In addition to recounting Mg nanocrystals synthetic refinement that was necessary for reproducible hydride kinetic analysis, Chapter 1 also briefly introduces some of the conventional models used for fitting of the hydriding kinetics data. Furthermore, initial investigations into the use of these models for our system are presented. Chapter 2 is a paper to be submitted to The Journal of Physical Chemistry C that describes the local and extended structure characterization of Mg nanocrystals (NCs) with a small amount of nickel added during synthesis. Ni has a dramatic effect on the de/hydriding kinetics of Mg NCs, and this chapter describes the use of a combination of multiple state-of-the-art characterization techniques to gain insight into the structural perturbations due to Ni inclusion in the Mg NCs. This insight is then used to establish the characteristics of Ni inclusion that results in the enhanced hydrogen

  5. Reducing metal alloy powder costs for use in powder bed fusion additive manufacturing: Improving the economics for production

    Science.gov (United States)

    Medina, Fransisco

    Titanium and its associated alloys have been used in industry for over 50 years and have become more popular in the recent decades. Titanium has been most successful in areas where the high strength to weight ratio provides an advantage over aluminum and steels. Other advantages of titanium include biocompatibility and corrosion resistance. Electron Beam Melting (EBM) is an additive manufacturing (AM) technology that has been successfully applied in the manufacturing of titanium components for the aerospace and medical industry with equivalent or better mechanical properties as parts fabricated via more traditional casting and machining methods. As the demand for titanium powder continues to increase, the price also increases. Titanium spheroidized powder from different vendors has a price range from 260/kg-450/kg, other spheroidized alloys such as Niobium can cost as high as $1,200/kg. Alternative titanium powders produced from methods such as the Titanium Hydride-Dehydride (HDH) process and the Armstrong Commercially Pure Titanium (CPTi) process can be fabricated at a fraction of the cost of powders fabricated via gas atomization. The alternative powders can be spheroidized and blended. Current sectors in additive manufacturing such as the medical industry are concerned that there will not be enough spherical powder for production and are seeking other powder options. It is believed the EBM technology can use a blend of spherical and angular powder to build fully dense parts with equal mechanical properties to those produced using traditional powders. Some of the challenges with angular and irregular powders are overcoming the poor flow characteristics and the attainment of the same or better packing densities as spherical powders. The goal of this research is to demonstrate the feasibility of utilizing alternative and lower cost powders in the EBM process. As a result, reducing the cost of the raw material to reduce the overall cost of the product produced with