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Sample records for hydride sorption beds

  1. Modeling of hydrogen isotopes separation in a metal hydride bed

    International Nuclear Information System (INIS)

    Charton, S.; Corriou, J.P.; Schweich, D.

    1999-01-01

    A predictive model for hydrogen isotopes separation in a non-isothermal bed of unsupported palladium hydride particles is derived. It accounts for the non-linear adsorption-dissociation equilibrium, hydrodynamic dispersion, pressure drop, mass transfer kinetics, heat of sorption and heat losses at the bed wall. Using parameters from the literature or estimated with classical correlations, the model gives simulated curves in agreement with previously published experiments without any parameter fit. The non-isothermal behavior is shown to be responsible for drastic changes of the mass transfer rate which is controlled by diffusion in the solid-phase lattice. For a feed at 300 K and atmospheric pressure, the endothermic hydride-to-deuteride exchange is kinetically controlled, whereas the reverse exothermic exchange is nearly at equilibrium. Finally, a simple and efficient thermodynamic model for the dissociative equilibrium between a metal and a diatomic gas is proposed. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

  2. Finite difference program for calculating hydride bed wall temperature profiles

    International Nuclear Information System (INIS)

    Klein, J.E.

    1992-01-01

    A QuickBASIC finite difference program was written for calculating one dimensional temperature profiles in up to two media with flat, cylindrical, or spherical geometries. The development of the program was motivated by the need to calculate maximum temperature differences across the walls of the Tritium metal hydrides beds for thermal fatigue analysis. The purpose of this report is to document the equations and the computer program used to calculate transient wall temperatures in stainless steel hydride vessels. The development of the computer code was motivated by the need to calculate maximum temperature differences across the walls of the hydrides beds in the Tritium Facility for thermal fatigue analysis

  3. Stress analysis of hydride bed vessels used for tritium storage

    International Nuclear Information System (INIS)

    McKillip, S.T.; Bannister, C.E.; Clark, E.A.

    1991-01-01

    A prototype hydride storage bed, using LaNi 4.25 Al 0.75 as the storage material, was fitted with strain gages to measure strains occurring in the stainless steel bed vessel caused by expansion of the storage powder upon uptake of hydrogen. The strain remained low in the bed as hydrogen was added, up to a bed loading of about 0.5 hydrogen to metal atom ratio (H/M). The strain then increased with increasing hydrogen loading (∼ 0.8 H/M). Different locations exhibited greatly different levels of maximum strain. In no case was the design stress of the vessel exceeded

  4. A low tritium hydride bed inventory estimation technique

    Energy Technology Data Exchange (ETDEWEB)

    Klein, J.E.; Shanahan, K.L.; Baker, R.A. [Savannah River National Laboratory, Aiken, SC (United States); Foster, P.J. [Savannah River Nuclear Solutions, Aiken, SC (United States)

    2015-03-15

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

  5. In-bed accountability of tritium in production scale metal hydride storage beds

    International Nuclear Information System (INIS)

    Klein, J.E.

    1995-01-01

    An ''in-bed accountability'' (IBA) flowing gas calorimetric measurement method has been developed and implemented to eliminate the need to remove tritium from production scale metal hydride storage beds for inventory measurement purposes. Six-point tritium IBA calibration curves have been completed for two, 390 gram tritium metal hydride storage beds. The calibration curves for the two tritium beds are similar to those obtained from the ''cold'' test program. Tritium inventory errors at the 95 percent confidence level ranged from ± 7.3 to 8.6 grams for the cold test results compared to ± 4.2 to 7.5 grams obtained for the two tritium calibrated beds

  6. Improved hydrogen sorption kinetics in wet ball milled Mg hydrides

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Li

    2011-05-04

    In this work, wet ball milling method is used in order to improve hydrogen sorption behaviour due to its improved microstructure of solid hydrogen materials. Compared to traditional ball milling method, wet ball milling has benefits on improvement of MgH{sub 2} microstructure and further influences on its hydrogen sorption behavior. With the help of solvent tetrahydrofuran (THF), wet ball milled MgH{sub 2} powder has much smaller particle size and its specific surface area is 7 times as large as that of dry ball milled MgH{sub 2} powder. Although after ball milling the grain size is decreased a lot compared to as-received MgH{sub 2} powder, the grain size of wet ball milled MgH{sub 2} powder is larger than that of dry ball milled MgH{sub 2} powder due to the lubricant effect of solvent THF during wet ball milling. The improved particle size and specific surface area of wet ball milled MgH{sub 2} powder is found to be determining its hydrogen sorption kinetics especially at relatively low temperatures. And it also shows good cycling sorption behavior, which decides on its industrial applicability. With three different catalysts MgH{sub 2} powder shows improved hydrogen sorption behavior as well as the cyclic sorption behavior. Among them, the Nb{sub 2}O{sub 5} catalyst is found to be the most effective one in this work. Compared to the wet ball milled MgH{sub 2} powder, the particle size and specific surface area of the MgH{sub 2} powder with catalysts are similar to the previous ones, while the grain size of the MgH{sub 2} with catalysts is much finer. In this case, two reasons for hydrogen sorption improvement are suggested: one is the reduction of the grain size. The other may be as pointed out in some literatures that formation of new oxidation could enhance the hydrogen sorption kinetics, which is also the reason why its hydrogen capacity is decreased compared to without catalysts. After further ball milling, the specific surface area of wet ball milled Mg

  7. Alternatives for metal hydride storage bed heating and cooling

    International Nuclear Information System (INIS)

    Fisher, I.A.; Ramirez, F.B.; Koonce, J.E.; Ward, D.E.; Heung, L.K.; Weimer, M.; Berkebile, W.; French, S.T.

    1991-01-01

    The reaction of hydrogen isotopes with the storage bed hydride material is exothermic during absorption and endothermic during desorption. Therefore, storage bed operation requires a cooling system to remove heat during absorption, and a heating system to add the heat needed for desorption. Three storage bed designs and their associated methods of heating and cooling and accountability are presented within. The first design is the current RTF (Replacement Tritium Facility) nitrogen heating and cooling system. The second design uses natural convection cooling with ambient glove box nitrogen and electrical resistance for heating. This design is referred to as the Naturally Cooled/Electrically Heated (NCEH) design. The third design uses forced convection cooling with ambient glove box nitrogen and electrical resistance for heating. The design is referred to as the Forced Convection Cooled/Electrically Heated (FCCEH) design. In this report the operation, storage bed design, and equipment required for heating, cooling, and accountability of each design are described. The advantages and disadvantages of each design are listed and discussed. Based on the information presented within, it is recommended that the NCEH design be selected for further development

  8. Thermal enhancement cartridge heater modified tritium hydride bed development, Part 2 - Experimental validation of key conceptual design features

    Energy Technology Data Exchange (ETDEWEB)

    Heroux, K.J.; Morgan, G.A. [Savannah River Laboratory, Aiken, SC (United States)

    2015-03-15

    The Thermal Enhancement Cartridge Heater Modified (TECH Mod) tritium hydride bed is an interim replacement for the first generation (Gen1) process hydride beds currently in service in the Savannah River Site (SRS) Tritium Facilities. 3 new features are implemented in the TECH Mod hydride bed prototype: internal electric cartridge heaters, porous divider plates, and copper foam discs. These modifications will enhance bed performance and reduce costs by improving bed activation and installation processes, in-bed accountability measurements, end-of-life bed removal, and He-3 recovery. A full-scale hydride bed test station was constructed at the Savannah River National Laboratory (SRNL) in order to evaluate the performance of the prototype TECH Mod hydride bed. Controlled hydrogen (H{sub 2}) absorption/ desorption experiments were conducted to validate that the conceptual design changes have no adverse effects on the gas transfer kinetics or H{sub 2} storage/release properties compared to those of the Gen1 bed. Inert gas expansions before, during, and after H{sub 2} flow tests were used to monitor changes in gas transfer rates with repeated hydriding/de-hydriding of the hydride material. The gas flow rates significantly decreased after initial hydriding of the material; however, minimal changes were observed after repeated cycling. The data presented herein confirm that the TECH Mod hydride bed would be a suitable replacement for the Gen1 bed with the added enhancements expected from the advanced design features. (authors)

  9. Thermal enhancement cartridge heater modified (TECH Mod) tritium hydride bed development, Part 1 - Design and fabrication

    Energy Technology Data Exchange (ETDEWEB)

    Klein, J.E.; Estochen, E.G. [Savannah River National Laboratory, Aiken, SC (United States)

    2015-03-15

    The Savannah River Site (SRS) tritium facilities have used first generation (Gen1) LaNi{sub 4.25}Al{sub 0.75} (LANA0.75) metal hydride storage beds for tritium absorption, storage, and desorption. The Gen1 design utilizes hot and cold nitrogen supplies to thermally cycle these beds. Second and third generation (Gen2 and Gen3) storage bed designs include heat conducting foam and divider plates to spatially fix the hydride within the bed. For thermal cycling, the Gen2 and Gen3 beds utilize internal electric heaters and glovebox atmosphere flow over the bed inside the bed external jacket for cooling. The currently installed Gen1 beds require replacement due to tritium aging effects on the LANA0.75 material, and cannot be replaced with Gen2 or Gen3 beds due to different designs of these beds. At the end of service life, Gen1 bed desorption efficiencies are limited by the upper temperature of hot nitrogen supply. To increase end-of-life desorption efficiency, the Gen1 bed design was modified, and a Thermal Enhancement Cartridge Heater Modified (TECH Mod) bed was developed. Internal electric cartridge heaters in the new design to improve end-of-life desorption, and also permit in-bed tritium accountability (IBA) calibration measurements to be made without the use of process tritium. Additional enhancements implemented into the TECH Mod design are also discussed. (authors)

  10. A FIXED BED SORPTION SYSTEM FOR DEFLUORIDATION OF GROUND WATER

    Directory of Open Access Journals (Sweden)

    Ayoob Sulaiman

    2009-06-01

    Full Text Available The presence of excess fluoride in ground water has become a global threat with as many as 200 million people affected in more than 35 countries in all the continents. Of late, there have been significant advances in the knowledge base regarding the effects of excess fluoride on human health. As a result, defluoridation of ground water is regarded as one of the key areas of attention among the universal water community triggering global research. This study describes the sorptive responses of a newly developed adsorbent, alumina cement granules (ALC, in its real-life application in fixed beds, for removing fluoride from the ground waters of a rural Indian village. ALC exhibited almost consistent scavenging capacity at various bed depths in column studies with an enhanced adsorption potential of 0.818 mg/g at a flow rate of 4 ml/min. The Thomas model was examined to describe the sorption process. The process design parameters of the column were obtained by linear regression of the model. In all the conditions examined, the Thomas model could consistently predict its characteristic parameters and describe the breakthrough sorption profiles in the whole range of sorption process.

  11. Performance of a full-scale ITER metal hydride storage bed in comparison with requirements

    International Nuclear Information System (INIS)

    Beloglazov, S.; Glugla, M.; Fanghaenel, E.; Perevezentsev, A.; Wagner, R.

    2008-01-01

    The storage of hydrogen isotopes as metal hydride is the technique chosen for the ITER Tritium Plant Storage and Delivery System (SDS). A prototype storage bed of a full-scale has been designed, manufactured and intensively tested at the Tritium Laboratory, addressing main performance parameters specified for the ITER application. The main requirements for the hydrogen storage bed are a strict physical limitation of the tritium storage capacity (currently 70 g T 2 ), a high supply flow rate of hydrogen isotopes, in-situ calorimetry capabilities with an accuracy of 1 g and a fully tritium compatible design. The pressure composition isotherm of the ZrCo hydrogen system, as a reference material for ITER, is characterised by significant slope. As a result technical implementation of the ZrCo hydride bed in the SDS system requires further considerations. The paper presents the experience from the operation of ZrCo getter bed including loading/de-loading operation, calorimetric loop performance, and active gas cooling of the bed for fast absorption operation. The implications of hydride material characteristics on the SDS system configuration and design are discussed. (authors)

  12. 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.

  13. Study on the effects of titanium oxide based nanomaterials as catalysts on the hydrogen sorption kinetics of magnesium hydride

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, Anderson de Farias; Jardim, Paula Mendes; Santos, Dilson Silva dos, E-mail: anderso.n@poli.ufrj.br [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil); Conceicao, Monique Osorio Talarico da [Centro Universitario de Volta Redonda (UniFOA), RJ (Brazil)

    2016-07-01

    Full text: Magnesium hydride is highly attractive for hydrogen storage in solid state in reason of its high gravimetric capacity (7,6 wt% of H{sub 2}) and low density (1,7 g/cm³), making it a promissory candidate for mobile applications [1]. However, its low sorption kinetics and desorption temperature are the main obstacles for its application. In the present study the catalytic role of TiO{sub 2} based nanomaterials with different morphologies on the sorption kinetics of MgH{sub 2} was evaluated. The additions consisted on titanate nanotubes (TTNT-Low), TiO{sub 2} nanorods (TTNT-550) and nanoparticles (KA-100, TTNT-ACID). Transmission and Scanning Transmission Electron Microscopy (S/TEM) associated with X-ray Energy Dispersive Spectroscopy (XEDS) mapping was used to characterize the catalysts' morphology and crystalline structure and their dispersion within magnesium hydride, altogether with other characterization techniques such as X-ray diffraction (XRD) and BET technique for structure and surface area analysis. The sorption kinetics were evaluated by means of a volumetric gas absorption/desorption (Sievert-type) apparatus. The results indicated that all additives improved the sorption kinetics of MgH{sub 2}, but the samples with TTNT-550 (TiO{sub 2} nanorods) and TTNT-ACID (TiO{sub 2} nanoparticles) presented the best and the second best performances, respectively, suggesting that the 1D morphology may promote a slightly superior kinetics than particulate catalysts. (author)

  14. Sorption-enhanced steam methane reforming in fluidized bed reactors

    Energy Technology Data Exchange (ETDEWEB)

    Johnsen, Kim

    2006-10-15

    Hydrogen is considered to be an important potential energy carrier; however, its advantages are unlikely to be realized unless efficient means can be found to produce it without generation of CO{sub 2}. Sorption-enhanced steam methane reforming (SE-SMR) represent a novel, energy-efficient hydrogen production route with in situ CO{sub 2} capture, shifting the reforming and water gas shift reactions beyond their conventional thermodynamic limits. The use of fluidized bed reactors for SE-SMR has been investigated. Arctic dolomite, a calcium-based natural sorbent, was chosen as the primary CO{sub 2}-acceptor in this study due to high absorption capacity, relatively high reaction rate and low cost. An experimental investigation was conducted in a bubbling fluidized bed reactor of diameter 0.1 m, which was operated cyclically and batch wise, alternating between reforming/carbonation conditions and higher-temperature calcination conditions. Hydrogen concentrations of >98 mole% on a dry basis were reached at 600 C and 1 atm, for superficial gas velocities in the range of {approx}0.03-0.1 m/s. Multiple reforming-regeneration cycles showed that the hydrogen concentration remained at {approx}98 mole% after four cycles. The total production time was reduced with an increasing number of cycles due to loss of CO{sub 2}-uptake capacity of the dolomite, but the reaction rates of steam reforming and carbonation seemed to be unaffected for the conditions investigated. A modified shrinking core model was applied for deriving carbonation kinetics of Arctic dolomite, using experimental data from a novel thermo gravimetric reactor. An apparent activation energy of 32.6 kj/mole was found from parameter fitting, which is in good agreement with previous reported results. The derived rate expression was able to predict experimental conversion up to {approx}30% very well, whereas the prediction of higher conversion levels was poorer. However, the residence time of sorbent in a continuous

  15. Reversible Li-insertion in nanoscaffolds: A promising strategy to alter the hydrogen sorption properties of Li-based complex hydrides

    NARCIS (Netherlands)

    Ngene, Peter; Verkuijlen, Margriet H. W.; Barre, Charlotte; Kentgens, Arno P. M.; de Jongh, Petra E.

    Intercalation and de-intercalation of lithium into graphene layers is a well-established phenomenon in Li-ion battery technology. Here we show how this phenomenon can be exploited to destabilize, and alter the hydrogen sorption behaviour of Li-based metal hydrides (LiBH4 and LiAlH4), thereby

  16. Cadmium removal by bioclastic granules (Lithothamnium calcareum): batch and fixed-bed column systems sorption studies.

    Science.gov (United States)

    Veneu, Diego Macedo; Schneider, Claudio Luiz; de Mello Monte, Marisa Bezerra; Cunha, Osvaldo Galvão Caldas; Yokoyama, Lídia

    2017-06-19

    The potential of Bioclastic Granules - BG (calcium-carbonate-based material) using the algae Lithothamnium calcareum as sorbent for the removal of Cd(II) from aqueous solutions by sorption was evaluated through batch and continuous systems tests using a fixed-bed column. Sorption process variables, in particular pH (2-7), particle size (<38-300 μm), initial BG concentration (0.1-1.0 g L -1 ), initial Cd(II) concentrations (5-400 mg L -1 ) and contact time (5-240 min), were evaluated. Adsorption isotherm profiles of Cd(II) per BG were similar to an L-type, or Langmuir type, with the adsorption forming a monolayer of approximately 0.61 μm, with a q max of 188.74 mg g -1 and k L of 0.710 L mg -1 . Thomas's model considers that sorption is not limited to a chemical reaction but is controlled by mass transfer at the interface. In the present study, the obtained value of k Th was 0.895 mL h -1  mg -1 , reaching a sorption capacity q o of 124.4 mg g -1 . For the Yoon-Nelson model, it was possible to obtain two important parameters to describe the behavior of the column, the rate constant (k YN ), obtaining a value of 0.09 h -1 and an τ of 82.12 h corresponding to the time required for sorption to occur of 50% of the solute in the rupture curve. X-ray diffraction and scanning electron microscopy analyses coupled to the X-ray dispersive energy system (SEM/EDS) of the BG after the Cd(II) ion sorption tests evidenced the formation of crystals with the prevalence of a new mineral phase (otavite).

  17. Predictive models of circulating fluidized bed combustors: SO[sub 2] sorption in the CFB loop

    Energy Technology Data Exchange (ETDEWEB)

    Gidaspow, D.; Therdthianwong, A. (Illinois Inst. of Tech., Chicago, IL (United States). Dept. of Chemical Engineering)

    1993-02-01

    The overall objective of this investigation is to develop experimentally verified models for circulating fluidized bed (CFB) combustors. Sorption of S0[sub 2] with calcined limestone was studied in a PYROFLOW type CFB loop at conditions approximating those found in a CFB combustor. Initially the CFB loop contained 150 micron CaO particles of a density of 3.3 g/cm[sup 3] and air at 1143[degrees]K and 3.25 atm. Atzero time, air containing 600 ppm SO[sub 2], was introduced into the riser bottom at 1143[degrees]K. The effect of gas velocity, sorbent inventory and inlet pressure on the sorption of SO[sub 2], were studied isothermally by running our hydrodynamic code with the S0[sub 2] sorption conservation of species equation. At a velocity of 5m/sec., reported to be a typical velocity by PYROPOWER, there is reasonably good S0[sub 2] removal. At 10 m/sec the S0[sub 2] removal is poor. The best SO[sub 2], removal is for a velocity of 5 m/s and a high bed inventory, initial bed height, H = 9m. Most of the S0[sub 2] is removed in the first two meters of the reactor. However, the S0[sub 2] removal is not complete at the bed outlet. This is due to mixing. At the left wall of the reactor (wall opposite the solids inlet) the S0[sub 2] removal was poor due to gas bypassing caused by the asymmetrical solids inlet. Simulation of the PYROPOWER loop with a symmetrical inlet gave us an order of magnitude improvement over the conventional PYROPOWER system. These results demonstrate the practical utility of the predictive model that we have developed over the last three years.

  18. Continuous cadmium removal from aqueous solutions by seaweed in a packed-bed column under consecutive sorption-desorption cycles

    International Nuclear Information System (INIS)

    Jafari, Seyed Ali; Jamali, Abbas

    2016-01-01

    Packed-bed column process efficiency for cadmium adsorption from aqueous solution was investigated under different bed heights (2.6 to 7.5 cm) and feed flow rates (15 to 30 ml min -1 ). The column was filled with brown seaweed, Sargassum angustifolium. Three simplified models, including Bed Depth Service Time, Thomas, and Yoon- Nelson were employed for describing the experimental breakthrough curves as well as achieving design parameters. Bed lifetime was also evaluated in several consecutive sorption-desorption cycles. Cadmium concentration of 0.005mg l−1, as a standard limit for potable water, was considered as the breakthrough concentration. The maximum column performance was achieved 81% at 7.5 cm bed length and flow rate of 15 ml min -1 . Indeed, increasing the bed height increased the sorption performance and service time, while increasing the feed flow rate had a negative effect. Maximum sorption capacity value remained almost constant by the bed height changes; however, increase in the feed flow rate slightly decreased it. The modeling results revealed that the Yoon-Nelson model was more accurate than Thomas for describing the experimental breakthrough data, especially at low flow rates. Column service time predictions were surprisingly achieved using the Bed Depth Service Time model even at extrapolations. 20% reduction in column adsorption efficiency was observed at the end of four consecutive sorption-desorption cycles; however, desorption efficiencies were achieved more than 99% in each cycle.

  19. Continuous cadmium removal from aqueous solutions by seaweed in a packed-bed column under consecutive sorption-desorption cycles

    Energy Technology Data Exchange (ETDEWEB)

    Jafari, Seyed Ali; Jamali, Abbas [Persian Gulf Research Institute, Persian Gulf University, 75169, Bushehr (Iran, Islamic Republic of)

    2016-04-15

    Packed-bed column process efficiency for cadmium adsorption from aqueous solution was investigated under different bed heights (2.6 to 7.5 cm) and feed flow rates (15 to 30 ml min{sup -1}). The column was filled with brown seaweed, Sargassum angustifolium. Three simplified models, including Bed Depth Service Time, Thomas, and Yoon- Nelson were employed for describing the experimental breakthrough curves as well as achieving design parameters. Bed lifetime was also evaluated in several consecutive sorption-desorption cycles. Cadmium concentration of 0.005mg l−1, as a standard limit for potable water, was considered as the breakthrough concentration. The maximum column performance was achieved 81% at 7.5 cm bed length and flow rate of 15 ml min{sup -1}. Indeed, increasing the bed height increased the sorption performance and service time, while increasing the feed flow rate had a negative effect. Maximum sorption capacity value remained almost constant by the bed height changes; however, increase in the feed flow rate slightly decreased it. The modeling results revealed that the Yoon-Nelson model was more accurate than Thomas for describing the experimental breakthrough data, especially at low flow rates. Column service time predictions were surprisingly achieved using the Bed Depth Service Time model even at extrapolations. 20% reduction in column adsorption efficiency was observed at the end of four consecutive sorption-desorption cycles; however, desorption efficiencies were achieved more than 99% in each cycle.

  20. A coupled transport and solid mechanics formulation with improved reaction kinetics parameters for modeling oxidation and decomposition in a uranium hydride bed.

    Energy Technology Data Exchange (ETDEWEB)

    Salloum, Maher N.; Shugard, Andrew D.; Kanouff, Michael P.; Gharagozloo, Patricia E.

    2013-03-01

    Modeling of reacting flows in porous media has become particularly important with the increased interest in hydrogen solid-storage beds. An advanced type of storage bed has been proposed that utilizes oxidation of uranium hydride to heat and decompose the hydride, releasing the hydrogen. To reduce the cost and time required to develop these systems experimentally, a valid computational model is required that simulates the reaction of uranium hydride and oxygen gas in a hydrogen storage bed using multiphysics finite element modeling. This SAND report discusses the advancements made in FY12 (since our last SAND report SAND2011-6939) to the model developed as a part of an ASC-P&EM project to address the shortcomings of the previous model. The model considers chemical reactions, heat transport, and mass transport within a hydride bed. Previously, the time-varying permeability and porosity were considered uniform. This led to discrepancies between the simulated results and experimental measurements. In this work, the effects of non-uniform changes in permeability and porosity due to phase and thermal expansion are accounted for. These expansions result in mechanical stresses that lead to bed deformation. To describe this, a simplified solid mechanics model for the local variation of permeability and porosity as a function of the local bed deformation is developed. By using this solid mechanics model, the agreement between our reacting bed model and the experimental data is improved. Additionally, more accurate uranium hydride oxidation kinetics parameters are obtained by fitting the experimental results from a pure uranium hydride oxidation measurement to the ones obtained from the coupled transport-solid mechanics model. Finally, the coupled transport-solid mechanics model governing equations and boundary conditions are summarized and recommendations are made for further development of ARIA and other Sandia codes in order for them to sufficiently implement the model.

  1. 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.

  2. 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.

  3. Fixed bed sorption of phosphorus from wastewater using iron oxide-based media derived from acid mine drainage

    Science.gov (United States)

    Sibrell, Philip L.; Tucker, T.W.

    2012-01-01

    Phosphorus (P) releases to the environment have been implicated in the eutrophication of important water bodies worldwide. Current technology for the removal of P from wastewaters consists of treatment with aluminum (Al) or iron (Fe) salts, but is expensive. The neutralization of acid mine drainage (AMD) generates sludge rich in Fe and Al oxides that has hitherto been considered a waste product, but these sludges could serve as an economical adsorption media for the removal of P from wastewaters. Therefore, we have evaluated an AMD-derived media as a sorbent for P in fixed bed sorption systems. The homogenous surface diffusion model (HSDM) was used to analyze fixed bed test data and to determine the value of related sorption parameters. The surface diffusion modulus Ed was found to be a useful predictor of sorption kinetics. Values of Ed treatment costs while at the same time ameliorating the impacts of P contamination.

  4. Fixed bed sorption of phosphorus from wastewater using iron oxide-based media derived from acid mine drainage

    Science.gov (United States)

    Sibrell, Philip L.; Tucker, T.W.

    2012-01-01

    Phosphorus (P) releases to the environment have been implicated in the eutrophication of important water bodies worldwide. Current technology for the removal of P from wastewaters consists of treatment with aluminum (Al) or iron (Fe) salts, but is expensive. The neutralization of acid mine drainage (AMD) generates sludge rich in Fe and Al oxides that has hitherto been considered a waste product, but these sludges could serve as an economical adsorption media for the removal of P from wastewaters. Therefore, we have evaluated an AMD-derived media as a sorbent for P in fixed bed sorption systems. The homogenous surface diffusion model (HSDM) was used to analyze fixed bed test data and to determine the value of related sorption parameters. The surface diffusion modulus Ed was found to be a useful predictor of sorption kinetics. Values of Ed < 0.2 were associated with early breakthrough of P, while more desirable S-shaped breakthrough curves resulted when 0.2 < Ed < 0.5. Computer simulations of the fixed bed process with the HSDM confirmed that if Ed was known, the shape of the breakthrough curve could be calculated. The surface diffusion coefficient D s was a critical factor in the calculation of Ed and could be estimated based on the sorption test conditions such as media characteristics, and influent flow rate and concentration. Optimal test results were obtained with a relatively small media particle size (average particle radius 0.028 cm) and resulted in 96 % removal of P from the influent over 46 days of continuous operation. These results indicate that fixed bed sorption of P would be a feasible option for the utilization of AMD residues, thus helping to decrease AMD treatment costs while at the same time ameliorating the impacts of P contamination.

  5. Sorption processes affecting arsenic solubility in oxidized surface sediments from Tulare Lake Bed, California

    Science.gov (United States)

    Gao, S.; Goldberg, S.; Herbel, M.J.; Chalmers, A.T.; Fujii, R.; Tanji, K.K.

    2006-01-01

    Elevated concentrations of arsenic (As) in shallow groundwater in Tulare Basin pose an environmental risk because of the carcinogenic properties of As and the potential for its migration to deep aquifers that could serve as a future drinking water source. Adsorption and desorption are hypothesized to be the major processes controlling As solubility in oxidized surface sediments where arsenate [As(V)] is dominant. This study examined the relationship between sorption processes and arsenic solubility in shallow sediments from the dry Tulare Lake bed by determining sorption isotherms, pH effect on solubility, and desorption-readsorption behavior (hysteresis), and by using a surface complexation model to describe sorption. The sediments showed a high capacity to adsorb As(V). Estimates of the maximum adsorption capacity were 92 mg As kg- 1 at pH 7.5 and 70 mg As kg- 1 at pH 8.5 obtained using the Langmuir adsorption isotherm. Soluble arsenic [> 97% As(V)] did not increase dramatically until above pH 10. In the native pH range (7.5-8.5), soluble As concentrations were close to the lowest, indicating that As was strongly retained on the sediment. A surface complexation model, the constant capacitance model, was able to provide a simultaneous fit to both adsorption isotherms (pH 7.5 and 8.5) and the adsorption envelope (pH effect on soluble As), although the data ranges are one order of magnitude different. A hysteresis phenomenon between As adsorbed on the sediment and As in solution phase was observed in the desorption-readsorption processes and differs from conventional hysteresis observed in adsorption-desorption processes. The cause is most likely due to modification of adsorbent surfaces in sediment samples upon extensive extractions (or desorption). The significance of the hysteresis phenomenon in affecting As solubility and mobility may be better understood by further microscopic studies of As interaction mechanisms with sediments subjected to extensive leaching

  6. Predictive models of circulating fluidized bed combustors: SO{sub 2} sorption in the CFB loop. Fourteenth technical progress report

    Energy Technology Data Exchange (ETDEWEB)

    Gidaspow, D.; Therdthianwong, A. [Illinois Inst. of Tech., Chicago, IL (United States). Dept. of Chemical Engineering

    1993-02-01

    The overall objective of this investigation is to develop experimentally verified models for circulating fluidized bed (CFB) combustors. Sorption of S0{sub 2} with calcined limestone was studied in a PYROFLOW type CFB loop at conditions approximating those found in a CFB combustor. Initially the CFB loop contained 150 micron CaO particles of a density of 3.3 g/cm{sup 3} and air at 1143{degrees}K and 3.25 atm. Atzero time, air containing 600 ppm SO{sub 2}, was introduced into the riser bottom at 1143{degrees}K. The effect of gas velocity, sorbent inventory and inlet pressure on the sorption of SO{sub 2}, were studied isothermally by running our hydrodynamic code with the S0{sub 2} sorption conservation of species equation. At a velocity of 5m/sec., reported to be a typical velocity by PYROPOWER, there is reasonably good S0{sub 2} removal. At 10 m/sec the S0{sub 2} removal is poor. The best SO{sub 2}, removal is for a velocity of 5 m/s and a high bed inventory, initial bed height, H = 9m. Most of the S0{sub 2} is removed in the first two meters of the reactor. However, the S0{sub 2} removal is not complete at the bed outlet. This is due to mixing. At the left wall of the reactor (wall opposite the solids inlet) the S0{sub 2} removal was poor due to gas bypassing caused by the asymmetrical solids inlet. Simulation of the PYROPOWER loop with a symmetrical inlet gave us an order of magnitude improvement over the conventional PYROPOWER system. These results demonstrate the practical utility of the predictive model that we have developed over the last three years.

  7. Sorption properties of nanocrystalline metal hydrides for the storage of hydrogen; Sorptionseigenschaften von nanokristallinen Metallhydriden fuer die Wasserstoffspeicherung

    Energy Technology Data Exchange (ETDEWEB)

    Oelerich, W.

    2000-07-01

    For the utilisation of hydrogen in emission-free automobiles new nanostructured Mg-based metal hydrides were developed. These materials show significantly faster absorption and desorption kinetics, which can be even further enhanced by additions of suitable catalysts. Contrary to conventional magnesium powder, hydrogenation at room temperature is demonstrated for the first time. During dehydrogenation at 250 C a desorption rate of 3 to 8 kW/kg with a capacity of 2.5 kWh/kg is achieved, that fulfills the technical requirements for automobile application. (orig.) [German] Im Hinblick auf den Einsatz von Wasserstoff in emissionsfreien Kraftfahrzeugen wurden neuartige nanostrukturierte Metallhydride auf Basis von Magnesium hergestellt. Diese Materialien zeigen eine deutlich schnellere Absorptions- und Desorptionskinetik, die sich durch den Zusatz von geeigneten Katalysatoren noch weiter steigern laesst. Im Gegensatz zu konventionellem Magnesiumpulver konnte erstmals eine Hydrierung bei Raumtemperatur demonstriert werden. Bei der Dehydrierung bei 250 C wird eine Desorptionsrate von 3 bis 8 kW/kg bei einer Kapazitaet von 2,5 kWh/kg erreicht, die die technischen Leistungsanforderungen von Kraftfahrzeugen erfuellt. (orig.)

  8. Bed geometries, fueling strategies and optimization of heat exchanger designs in metal hydride storage systems for automotive applications: A review

    DEFF Research Database (Denmark)

    Mazzucco, Andrea; Dornheim, Martin; Sloth, Michael

    2014-01-01

    This review presents recent developments for effective heat management systems to be integrated in metal hydride storage tanks, and investigates the performance improvements and limitations of each particular solution. High pressures and high temperatures metal hydrides can lead to different design...... given to metal hydride storage tanks for light duty vehicles, since this application is the most promising one for such storage materials and has been widely studied in the literature. Enhancing cooling/heating during hydrogen uptake and discharge has found to be essential to improve storage systems...

  9. 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

  10. Tritium sorption behavior on the percolation of tritiated water into a soil packed bed

    Energy Technology Data Exchange (ETDEWEB)

    Furuichi, Kazuya, E-mail: kfuruichi@aees.kyushu-u.ac.jp [Department of Advanced Energy Engineering, Kyushu University, 6-1, Kasuga-koen, Kasuga, Fukuoka 816-8580 (Japan); Katayama, Kazunari; Date, Hiroyuki [Department of Advanced Energy Engineering, Kyushu University, 6-1, Kasuga-koen, Kasuga, Fukuoka 816-8580 (Japan); Takeishi, Toshiharu [Factory of Engineering, Kyushu University, 744 Motooka Nishi-ku, Fukuoka 819-0395 (Japan); Fukada, Satoshi [Department of Advanced Energy Engineering, Kyushu University, 6-1, Kasuga-koen, Kasuga, Fukuoka 816-8580 (Japan)

    2016-11-01

    Highlights: • We establish the permeation model of tritiated water in the soil layer. • Saturated hydraulic conductivity of water in soil was gained by using the model. • The isotope exchange reaction coefficient was good agreement with experimental data. - Abstract: Development of tritium transport model in natural soil is an important issue from a viewpoint of safety of fusion reactors. The spill of a large amount of tritiated water to the environment is a concern accident because huge tritiated water is handled in a fusion plant. In this work, a simple tritium transport model was proposed based on the tritium transport model in porous materials. The overall mass transfer coefficient representing isotope exchange reaction between tritiated water and structural water in soil particles was obtained by numerically analyzing the result of the percolation experiment of tritiated water into the soil packed bed. Saturated hydraulic conductivity in the natural soil packed bed was obtained to be 0.033 mm/s. By using this value, the overall mass transfer capacity coefficients representing the isotope exchange reaction between tritiated water percolating through the packed bed and overall structural water on soil particles was determined to be 6.0 × 10{sup −4} 1/s. This value is much smaller than the mass transfer capacity coefficient between tritiated water vapor and water on concrete material and metals.

  11. HgCl{sub 2} sorption on lignite activated carbon: Analysis of fixed-bed results

    Energy Technology Data Exchange (ETDEWEB)

    Mibeck, Blaise A.F.; Olson, Edwin S.; Miller, Stanley J. [University of North Dakota Energy and Environmental Research Center, 15 North 23rd Street, Stop 9018, Grand Forks, ND 58202-9018 (United States)

    2009-11-15

    Factors that influence kinetic reactivity and equilibrium between elemental mercury, carbon, and flue gas components have been the focus of numerous studies. This study pertains to recent bench-scale fixed-bed tests in which activated carbon was exposed to HgCl{sub 2} in a flue gas composition typical of an unscrubbed eastern bituminous coal. Results are discussed in light of a refined binding site model based on the zigzag carbene structures recently proposed for electronic states at the edges of the carbon graphene layers. (author)

  12. Thermal design of a metal hydride storage bed, permitting tritium accountancy to 0.1% resolution and repeatability

    International Nuclear Information System (INIS)

    Hemmerich, J.L.

    1995-01-01

    Tritium storage beds at the International Thermonuclear Experimental Reactor are likely to use uranium as a getter material with a total inventory of 150 g T 2 at 75% stoichiometric composition of UT 3 . We propose a storage bed design directly extrapolated from the Joint European Torus uranium beds, which already have a 238 U inventory of 4.284 kg. Three alternative approaches to implement calorimetry for in situ tritium inventory accounting are discussed. The favored solution uses a microporous thermal insulation operating in a hydrogen atmosphere. This design is shown to meet all operational and safety requirements. The accuracy of calorimetric assay to ±0.1 requires only the measurement of a temperature difference to ±0.1 K and stabilization of the ambient reference temperature of 300 to ±0.1 K. 9 refs., 2 figs

  13. Hydrogen production by enhanced-sorption chemical looping steam reforming of glycerol in moving-bed reactors

    International Nuclear Information System (INIS)

    Dou, Binlin; Song, Yongchen; Wang, Chao; Chen, Haisheng; Yang, Mingjun; Xu, Yujie

    2014-01-01

    Highlights: • New approach on continuous high-purity H 2 produced auto-thermally with long time. • Low-cost NiO/NiAl 2 O 4 exhibited high redox performance to H 2 from glycerol. • Oxidation, steam reforming, WSG and CO 2 capture were combined into a reactor. • H 2 purity of above 90% was produced without heating at 1.5–3.0 S/C and 500–600 °C. • Sorbent regeneration and catalyst oxidization achieved simultaneously in a reactor. - Abstract: The continuous high-purity hydrogen production by the enhanced-sorption chemical looping steam reforming of glycerol based on redox reactions integrated with in situ CO 2 removal has been experimentally studied. The process was carried out by a flow of catalyst and sorbent mixture using two moving-bed reactors. Various unit operations including oxidation, steam reforming, water gas shrift reaction and CO 2 removal were combined into a single reactor for hydrogen production in an overall economic and efficient process. The low-cost NiO/NiAl 2 O 4 catalyst efficiently converted glycerol and steam to H 2 by redox reactions and the CO 2 produced in the process was simultaneously removed by CaO sorbent. The best results with an enriched hydrogen product of above 90% in auto-thermal operation for reforming reactor were achieved at initial temperatures of 500–600 °C and ratios of steam to carbon (S/C) of 1.5–3.0. The results indicated also that not all of NiO in the catalyst can be reduced to Ni by the reaction with glycerol, and the reduced Ni can be oxidized to NiO by air at 900 °C. The catalyst oxidization and sorbent regeneration were achieved under the same conditions in air reactor

  14. Batch desorption studies and multiple sorption-regeneration cycles in a fixed-bed column for Cd(II) elimination by protonated Sargassum muticum

    International Nuclear Information System (INIS)

    Lodeiro, P.; Herrero, R.; Sastre de Vicente, M.E.

    2006-01-01

    The protonated alga Sargassum muticum was employed in batch desorption studies to find the most appropriate eluting agent for Cd(II)-laden biomass regeneration. Eleven types of eluting solutions at different concentrations were tested, finding elution efficiencies higher than 90% for most of the desorbents studied. Total organic carbon and biomass weight loss measurements were made. The reusability of the protonated alga was also studied using a fixed-bed column. Eleven consecutive sorption-regeneration cycles at a flow rate of 10 mL min -1 were carried out for the removal of 50 mg L -1 Cd(II) solution. A 0.1 M HNO 3 solution was employed as desorbing agent. The column was operated during 605 h for sorption and 66 h for desorption, equivalent to a continuous use during 28 days, with no apparent loss of sorption performance. In these cycles, no diminution of the breakthrough time was found; although, a relative loss of sorption capacity, regarding the found in the first cycle, was observed. The slope of the breakthrough curves experiments a gradual increase reaching its maximum value for the last cycle tested (40% greater than for the first one). The maximum Cd(II) concentration elution peak was achieved in 5 min or less, and the metal effluent concentration was always lower than 0.9 mg L -1 after 1 h of elution. The maximum concentration factor was determined to be between 55 and 109

  15. Metal hydrides for hydrogen storage in nickel hydrogen batteries

    International Nuclear Information System (INIS)

    Bittner, H.F.; Badcock, C.C.; Quinzio, M.V.

    1984-01-01

    Metal hydride hydrogen storage in nickel hydrogen (Ni/H 2 ) batteries has been shown to increase battery energy density and improve battery heat management capabilities. However the properties of metal hydrides in a Ni/H 2 battery environment, which contains water vapor and oxygen in addition to the hydrogen, have not been well characterized. This work evaluates the use of hydrides in Ni/H 2 batteries by fundamental characterization of metal hydride properties in a Ni/H 2 cell environment. Hydrogen sorption properties of various hydrides have been measured in a Ni/H 2 cell environment. Results of detailed thermodynamic and kinetic studies of hydrogen sorption in LaNi 5 in a Ni/H 2 cell environment are presented. Long-term cycling studies indicate that degradation of the hydride can be minimized by cycling between certain pressure limits. A model describing the mechanism of hydride degradation is presented

  16. Selenium analysis by an integrated microwave digestion-needle trap device with hydride sorption on carbon nanotubes and electrothermal atomic absorption spectrometry determination

    Science.gov (United States)

    Maratta Martínez, Ariel; Vázquez, Sandra; Lara, Rodolfo; Martínez, Luis Dante; Pacheco, Pablo

    2018-02-01

    An integrated microwave assisted digestion (MW-AD) - needle trap device (NTD) for selenium determination in grape pomace samples is presented. The NTD was filled with oxidized multiwall carbon nanotubes (oxMWCNTS) where Se hydrides were preconcentrated. Determination was carried out by flow injection-electrothermal atomic absorption spectrometry (FI-ETAAS). The variables affecting the system were established by a multivariate design (Plackett Burman), indicating that the following variables significantly affect the system: sample amount, HNO3 digestion solution concentration, NaBH4 volume and elution volume. A Box-Behnken design was implemented to determine the optimized values of these variables. The system improved Se atomization in the graphite furnace, since only trapped hydrides reached the graphite furnace, and the pyrolysis stage was eliminated according to the aqueous matrix of the eluate. Under optimized conditions the system reached a limit of quantification of 0.11 μg kg- 1, a detection limit of 0.032 μg kg- 1, a relative standard deviation of 4% and a preconcentration factor (PF) of 100, reaching a throughput sample of 5 samples per hour. Sample analysis show Se concentrations between 0.34 ± 0.03 μg kg- 1 to 0.48 ± 0.03 μg kg- 1 in grape pomace. This system provides minimal reagents and sample consumption, eliminates discontinuous stages between samples processing reaching a simpler and faster Se analysis.

  17. CFD simulation of CO_2 sorption on K_2CO_3 solid sorbent in novel high flux circulating-turbulent fluidized bed riser: Parametric statistical experimental design study

    International Nuclear Information System (INIS)

    Thummakul, Theeranan; Gidaspow, Dimitri; Piumsomboon, Pornpote; Chalermsinsuwan, Benjapon

    2017-01-01

    Highlights: • Circulating-turbulent fluidization was proved to be advantage on CO_2 sorption. • The novel regime was proven to capture CO_2 higher than the conventional regimes. • Uniform solid particle distribution was observed in the novel fluidization regime. • The system continuity had more effect in the system than the process system mixing. • Parametric experimental design analysis was studied to evaluate significant factor. - Abstract: In this study a high flux circulating-turbulent fluidized bed (CTFB) riser was confirmed to be advantageous for carbon dioxide (CO_2) sorption on a potassium carbonate solid sorbent. The effect of various parameters on the CO_2 removal level was evaluated using a statistical experimental design. The most appropriate fluidization regime was found to occur between the turbulent and fast fluidization regimes, which was shown to capture CO_2 more efficiently than conventional fluidization regimes. The highest CO_2 sorption level was 93.4% under optimized CTFB operating conditions. The important parameters for CO_2 capture were the inlet gas velocity and the interactions between the CO_2 concentration and the inlet gas velocity and water vapor concentration. The CTFB regime had a high and uniform solid particle distribution in both the axial and radial system directions and could transport the solid sorbent to the regeneration reactor. In addition, the process system continuity had a stronger effect on the CO_2 removal level in the system than the process system mixing.

  18. Hydrogen storage in the form of metal hydrides

    Science.gov (United States)

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

    1984-01-01

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

  19. Disposal of tritium-exposed metal hydrides

    International Nuclear Information System (INIS)

    Nobile, A.; Motyka, T.

    1991-01-01

    A plan has been established for disposal of tritium-exposed metal hydrides used in Savannah River Site (SRS) tritium production or Materials Test Facility (MTF) R ampersand D operations. The recommended plan assumes that the first tritium-exposed metal hydrides will be disposed of after startup of the Solid Waste Disposal Facility (SWDF) Expansion Project in 1992, and thus the plan is consistent with the new disposal requiremkents that will be in effect for the SWDF Expansion Project. Process beds containing tritium-exposed metal hydride powder will be disposed of without removal of the powder from the bed; however, disposal of tritium-exposed metal hydride powder that has been removed from its process vessel is also addressed

  20. Techno-economic analysis of sorption-enhanced steam methane reforming in a fixed bed reactor network integrated with fuel cell

    Science.gov (United States)

    Diglio, Giuseppe; Hanak, Dawid P.; Bareschino, Piero; Mancusi, Erasmo; Pepe, Francesco; Montagnaro, Fabio; Manovic, Vasilije

    2017-10-01

    Sorption-enhanced steam methane reforming (SE-SMR) is a promising alternative for H2 production with inherent CO2 capture. This study evaluates the techno-economic performance of SE-SMR in a network of fixed beds and its integration with a solid oxide fuel cell (SE-SMR-SOFC) for power generation. The analysis revealed that both proposed systems are characterised by better economic performance than the reference systems. In particular, for SE-SMR the levelised cost of hydrogen is 1.6 €ṡkg-1 and the cost of CO2 avoided is 29.9 €ṡtCO2-1 (2.4 €ṡkg-1 and 50 €ṡtCO2-1, respectively, for SMR with CO2 capture) while for SE-SMR-SOFC the levelised cost of electricity is 0.078 €ṡkWh-1 and the cost of CO2 avoided is 36.9 €ṡtCO2-1 (0.080 €ṡkWh-1 and 80 €ṡtCO2-1, respectively, for natural gas-fired power plant with carbon capture). The sensitivity analysis showed that the specific cost of fuel and the capital cost of fuel cell mainly affect the economic performance of SE-SMR and SE-SMR-SOFC, respectively. The daily revenue of the SE-SMR-SOFC system is higher than that of the natural gas-fired power plant if the difference between the carbon tax and the CO2 transport and storage cost is > 6 €ṡtCO2-1.

  1. Metal Hydride Compression

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Terry A. [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Bowman, Robert [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Smith, Barton [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Anovitz, Lawrence [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Jensen, Craig [Hawaii Hydrogen Carriers LLC, Honolulu, HI (United States)

    2017-07-01

    Conventional hydrogen compressors often contribute over half of the cost of hydrogen stations, have poor reliability, and have insufficient flow rates for a mature FCEV market. Fatigue associated with their moving parts including cracking of diaphragms and failure of seal leads to failure in conventional compressors, which is exacerbated by the repeated starts and stops expected at fueling stations. Furthermore, the conventional lubrication of these compressors with oil is generally unacceptable at fueling stations due to potential fuel contamination. Metal hydride (MH) technology offers a very good alternative to both conventional (mechanical) and newly developed (electrochemical, ionic liquid pistons) methods of hydrogen compression. Advantages of MH compression include simplicity in design and operation, absence of moving parts, compactness, safety and reliability, and the possibility to utilize waste industrial heat to power the compressor. Beyond conventional H2 supplies of pipelines or tanker trucks, another attractive scenario is the on-site generating, pressuring and delivering pure H2 at pressure (≥ 875 bar) for refueling vehicles at electrolysis, wind, or solar generating production facilities in distributed locations that are too remote or widely distributed for cost effective bulk transport. MH hydrogen compression utilizes a reversible heat-driven interaction of a hydride-forming metal alloy with hydrogen gas to form the MH phase and is a promising process for hydrogen energy applications [1,2]. To deliver hydrogen continuously, each stage of the compressor must consist of multiple MH beds with synchronized hydrogenation & dehydrogenation cycles. Multistage pressurization allows achievement of greater compression ratios using reduced temperature swings compared to single stage compressors. The objectives of this project are to investigate and demonstrate on a laboratory scale a two-stage MH hydrogen (H2) gas compressor with a

  2. Tritium measurement technique using ''in-bed'' calorimetry

    International Nuclear Information System (INIS)

    Klein, J.E.; Mallory, M.K.; Nobile, A. Jr.

    1991-01-01

    One of the new technologies that has been introduced to the Savannah River Site (SRS) is the production scale use of metal hydride technology to store, pump, and compress hydrogen isotopes. For tritium stored in metal hydride storage beds, a unique relationship does not exist between the amount of tritium in the bed and the pressure-volume-temperature properties of the hydride material. Determining the amount of tritium in a hydride bed after desorbing the contents of the bed to a tank and performing pressure, volume, temperature, and composition (PVTC) measurements is not practical due to long desorption/absorption times and the inability to remove tritium ''heels'' from the metal hydride materials under normal processing conditions. To eliminate the need to remove tritium from hydride storage beds for measurement purposes, and ''in-bed'' tritium calorimetric measurement technique has been developed. The steady-state temperature rise of a gas stream flowing through a jacketed metal hydride storage bed is measured and correlated with power input to electric heaters used to simulate the radiolytic power generated by the decay of tritium to 3 He. Temperature rise results for prototype metal hydride storage beds and the effects of using different gases in the bed are shown. Linear regression results shows that for 95% confidence intervals, temperature rise measurements can be obtained in 14 hours and have an accuracy of ±1.6% of a tritium filled hydride storage bed

  3. Hydrogen-storing hydride complexes

    Science.gov (United States)

    Srinivasan, Sesha S [Tampa, FL; Niemann, Michael U [Venice, FL; Goswami, D Yogi [Tampa, FL; Stefanakos, Elias K [Tampa, FL

    2012-04-10

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

  4. Technical and economic evaluation of hydrogen storage systems based on light metal hydrides

    Energy Technology Data Exchange (ETDEWEB)

    Jepsen, Julian

    2014-07-01

    -up storage systems are designed, tested and described numerically by finite elements simulation. The influence of the tank diameter on sorption rates, hydrogen capacities and temperature profiles inside the material beds is demonstrated. Key aspects for the design of future light metal hydride storage tank systems were derived from the experimental obtained results and the theoretical simulation of Li-RHC as a representative model system for RHCs.

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

    International Nuclear Information System (INIS)

    Nasise, J.E.

    1988-01-01

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

  6. Acetone-butanol-ethanol competitive sorption simulation from single, binary, and ternary systems in a fixed-bed of KA-I resin.

    Science.gov (United States)

    Wu, Jinglan; Zhuang, Wei; Ying, Hanjie; Jiao, Pengfei; Li, Renjie; Wen, Qingshi; Wang, Lili; Zhou, Jingwei; Yang, Pengpeng

    2015-01-01

    Separation of butanol based on sorption methodology from acetone-butanol-ethanol (ABE) fermentation broth has advantages in terms of biocompatibility and stability, as well as economy, and therefore gains much attention. In this work a chromatographic column model based on the solid film linear driving force approach and the competitive Langmuir isotherm equations was used to predict the competitive sorption behaviors of ABE single, binary, and ternary mixture. It was observed that the outlet concentration of weaker retained components exceeded the inlet concentration, which is an evidence of competitive adsorption. Butanol, the strongest retained component, could replace ethanol almost completely and also most of acetone. In the end of this work, the proposed model was validated by comparison of the experimental and predicted ABE ternary breakthrough curves using the real ABE fermentation broth as a feed solution. © 2014 American Institute of Chemical Engineers.

  7. Preparation of beryllium hydride

    International Nuclear Information System (INIS)

    Roberts, C.B.

    1975-01-01

    A process is described for preparing beryllium hydride by the direct reaction of beryllium borohydride and aluminum hydride trimethylamine adduct. Volatile by-products and unreacted reactants are readily removed from the product mass by sublimation and/or evaporation. (U.S.)

  8. Sorption mechanisms and sorption models

    International Nuclear Information System (INIS)

    Fedoroff, M.; Lefevre, G.; Duc, M.; Neskovic, C.; Milonjic, S.

    2004-01-01

    Sorption at the solid-liquid interfaces play a major role in many phenomena and technologies: chemical separations, catalysis, biological processes, transport of toxic and radioactive species in surface and underground waters. The long term safety of radioactive waste repositories is based on artificial and natural barriers, intended to sorb radionuclides after the moment when the storage matrixes and containers will be corroded. Predictions on the efficiency of sorption for more than 10 6 years have to be done in order to demonstrate the safety of such depositories, what is a goal never encountered in the history of sciences and technology. For all these purposes, and, especially for the long term prediction, acquiring of sorption data constitutes only a first step of studies. Modeling based on a very good knowledge of sorption mechanisms is needed. In this review, we shall examine the main approaches and models used to quantify sorption processes, including results taken from the literature and from our own studies. We shall compare sorption models and examine their adequacy with sorption mechanisms. The cited references are only a few examples of the numerous articles published in that field. (orig.)

  9. Studies Regarding As(V Adsorption from Underground Water by Fe-XAD8-DEHPA Impregnated Resin. Equilibrium Sorption and Fixed-Bed Column Tests

    Directory of Open Access Journals (Sweden)

    Mihaela Ciopec

    2014-10-01

    Full Text Available The characteristics of arsenic adsorption onto Fe-XAD8-DEHPA resin were studied on the laboratory scale using aqueous solutions and natural underground waters. Amberlite XAD8 resin was impregnated with di(2-ethylhexyl phosphoric acid (DEHPA via the dry method of impregnation. Fe(III ions were loaded onto the impregnated resin by exploiting the high affinity of arsenic towards iron. The studies were conducted by both in contact and continuous modes. Kinetics data revealed that the removal of arsenic by Fe-XAD8-DEHPA resin is a pseudo-second-order reaction. The equilibrium data were modelled with Freundlich Langmuir and Dubinin Radushkevich (D-R isotherms and it was found that the Freundlich model give the poorest correlation coefficient. The maximum adsorption capacity obtained from the Langmuir isotherm is 22.6 µg As(V/g of Fe-XAD8-DEHPA resin. The mean free energy of adsorption was found in this study to be 7.2 kJ/mol and the ΔG° value negative (−9.2 kJ/mol. This indicates that the sorption process is exothermal, spontaneous and physical in nature. The studied Fe-XAD8-DEHPA resin showed excellent arsenic removal performance by sorption, both from synthetic solution and the natural water sample, and could be regenerated simply by using aqueous NaOH or HCl solutions.

  10. Regenerative Hydride Heat Pump

    Science.gov (United States)

    Jones, Jack A.

    1992-01-01

    Hydride heat pump features regenerative heating and single circulation loop. Counterflow heat exchangers accommodate different temperatures of FeTi and LaNi4.7Al0.3 subloops. Heating scheme increases efficiency.

  11. Alkali metal hydride formation

    International Nuclear Information System (INIS)

    1976-01-01

    The present invention relates to a method of producing alkali metal hydrides by absorbing hydrogen gas under pressure into a mixture of lower alkyl mono amines and alkali metal alkyl amides selected from sodium and potassium amides formed from said amines. The present invention also includes purification of a mixture of the amines and amides which contain impurities, such as is used as a catalytic exchange liquid in the enrichment of deuterium, involving the formation of the alkali metal hydride

  12. Blistering and hydride embrittlement

    International Nuclear Information System (INIS)

    Louthan, M.R. Jr.

    1975-01-01

    The effects of hydrogen on the mechanical properties of metals have been categorized into several groups. Two of the groups, hydrogen blistering and hydride embrittlement, are reasonably well understood, and problems relating to their occurrence may be avoided if that understanding is used as a basis for selecting alloys for hydrogen service. Blistering and hydride embrittlement are described along with several techniques of materials selection and used to minimize their adverse effects. (U.S.)

  13. Isotope exchange between gaseous hydrogen and uranium hydride powder

    International Nuclear Information System (INIS)

    Shugard, Andrew D.; Buffleben, George M.; Johnson, Terry A.; Robinson, David B.

    2014-01-01

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

  14. Conference 'Chemistry of hydrides' Proceedings

    International Nuclear Information System (INIS)

    1991-07-01

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

  15. Preparation of beryllium hydride

    International Nuclear Information System (INIS)

    Lowrance, B.R.

    1975-01-01

    A process is described for the preparation of beryllium hydride which comprises pyrolyzing, while in solution in a solvent inert under the reaction conditions, with respect to reactants and products and at a temperature in the range of about 100 0 to about 200 0 C, sufficient to result in the formation of beryllium hydride, a di-t-alkyl beryllium etherate wherein each tertiary alkyl radical contains from 4 to 20 carbon atoms. The pyrolysis is carried out under an atmosphere inert under the reaction conditions, with respect to reactants and products. (U.S.)

  16. Thermal coupling of a high temperature PEM fuel cell with a complex hydride tank

    DEFF Research Database (Denmark)

    Pfeifer, P.; Wall, C.; Jensen, Jens Oluf

    2009-01-01

    the possibilities of a thermal coupling of a high temperature PEM fuel cell operating at 160-200 degrees C. The starting temperatures and temperature hold-times before starting fuel cell operation, the heat transfer characteristics of the hydride storage tanks, system temperature, fuel cell electrical power......Sodium alanate doped with cerium catalyst has been proven to have fast kinetics for hydrogen ab- and de-sorption as well as a high gravimetric storage density around 5 wt%. The kinetics of hydrogen sorption can be improved by preparing the alanate as nanocrystalline material. However, the second...... decomposition step, i.e. the decomposition of the hexahydride to sodium hydride and aluminium which refers to 1.8 wt% hydrogen is supposed to happen above 110 degrees C. The discharge of the material is thus limited by the level of heat supplied to the hydride storage tank. Therefore, we evaluated...

  17. Hydrogen storage in sodium aluminum hydride.

    Energy Technology Data Exchange (ETDEWEB)

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

    2005-11-01

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

  18. Electrolytic hydriding and hydride distribution in zircaloy-4

    International Nuclear Information System (INIS)

    Gomes, M.H.L.

    1974-01-01

    A study has been made of the electrolytic hydriding of zircaloy-4 in the range 20-80 0 C, for reaction times from 5 to 30 hours, and the effect of potential, pH and dissolved oxygen has been investigated. The hydriding reaction was more sensitive to time and temperature conditions than to the electrochemical variables. It has been shown that a controlled introduction of hydrides in zircaloy is feasible. Hydrides were found to be plate like shaped and distributed mainly along grain-boundaries. It has been shown that hydriding kinetics do not follow a simple law but may be described by a Johnson-Mehl empirical equation. On the basis of this equation an activation energy of 9.400 cal/mol has been determined, which is close to the activation energy for diffusion of hydrogen in the hydride. (author)

  19. Preparation of beryllium hydride

    International Nuclear Information System (INIS)

    Bergeron, C.R.; Baker, R.W.

    1975-01-01

    Beryllium hydride of high bulk density, suitable for use as a component of high-energy fuels, is prepared by the pyrolysis, in solution in an inert solvent, of a ditertiary-alkyl beryllium. An agitator introduces mechanical energy into the reaction system, during the pyrolysis, at the rate of 0.002 to 0.30 horsepower per gallon of reaction mixture. (U.S.)

  20. Air and metal hydride battery

    Energy Technology Data Exchange (ETDEWEB)

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

    1998-12-31

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

  1. 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)

  2. Hydrogen Outgassing from Lithium Hydride

    Energy Technology Data Exchange (ETDEWEB)

    Dinh, L N; Schildbach, M A; Smith, R A; Balazs1, B; McLean II, W

    2006-04-20

    Lithium hydride is a nuclear material with a great affinity for moisture. As a result of exposure to water vapor during machining, transportation, storage and assembly, a corrosion layer (oxide and/or hydroxide) always forms on the surface of lithium hydride resulting in the release of hydrogen gas. Thermodynamically, lithium hydride, lithium oxide and lithium hydroxide are all stable. However, lithium hydroxides formed near the lithium hydride substrate (interface hydroxide) and near the sample/vacuum interface (surface hydroxide) are much less thermally stable than their bulk counterpart. In a dry environment, the interface/surface hydroxides slowly degenerate over many years/decades at room temperature into lithium oxide, releasing water vapor and ultimately hydrogen gas through reaction of the water vapor with the lithium hydride substrate. This outgassing can potentially cause metal hydriding and/or compatibility issues elsewhere in the device. In this chapter, the morphology and the chemistry of the corrosion layer grown on lithium hydride (and in some cases, its isotopic cousin, lithium deuteride) as a result of exposure to moisture are investigated. The hydrogen outgassing processes associated with the formation and subsequent degeneration of this corrosion layer are described. Experimental techniques to measure the hydrogen outgassing kinetics from lithium hydride and methods employing the measured kinetics to predict hydrogen outgassing as a function of time and temperature are presented. Finally, practical procedures to mitigate the problem of hydrogen outgassing from lithium hydride are discussed.

  3. Comparative study about hydrogen sorption in sponge and powder titanium

    International Nuclear Information System (INIS)

    Vasut, Felicia; Preda, Anisoara; Zamfirache, Marius; Ducu, Catalin; Malinovschi, Viorel

    2005-01-01

    Currently, hydrogen may be stored as a compressed gas or a cryogenic liquid. Neither method appears to be practical for many applications in which hydrogen use would otherwise be attractive. For example, gaseous storage of stationary fuel is not feasible because of the large volume or weight of the storage vessels. Liquid hydrogen could be use extensively but the liquefaction process is relatively expensive. The hydrogen can be stored for a long term with a high separation factor, as a solid metal hydride. Using hydride-forming metals and intermetallic compounds, for example, recovery, purification and storage of heavy isotopes in tritium containing system, can solve many problems arising in the nuclear-fuel cycle. The paper presents a comparative study about hydrogen sorption on two titanium structures: powder and sponge. Also, it is presented the characterization, by X-Ray diffraction, of two structures, before and after sorption process. From our results, one can conclude that sorption method is efficient for both samples. Kinetic curves indicates that sorption rate for titanium powder is lower than for sponge titanium. This is the effect of reaction surface, which is larger for powder titanium. Sorption capacity for hydrogen is lower in powder titanium for identical experimental conditions. The difference between storage capacities could be explained by activation temperature, which was lower for titanium powder than for sponge. (authors)

  4. Low-Cost Metal Hydride Thermal Energy Storage System for Concentrating Solar Power Systems

    Energy Technology Data Exchange (ETDEWEB)

    Zidan, Ragaiy [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Hardy, B. J. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Corgnale, C. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Teprovich, J. A. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Ward, P. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Motyka, Ted [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2016-01-31

    The objective of this research was to evaluate and demonstrate a metal hydride-based TES system for use with a CSP system. A unique approach has been applied to this project that combines our modeling experience with the extensive material knowledge and expertise at both SRNL and Curtin University (CU). Because of their high energy capacity and reasonable kinetics many metal hydride systems can be charged rapidly. Metal hydrides for vehicle applications have demonstrated charging rates in minutes and tens of minutes as opposed to hours. This coupled with high heat of reaction allows metal hydride TES systems to produce very high thermal power rates (approx. 1kW per 6-8 kg of material). A major objective of this work is to evaluate some of the new metal hydride materials that have recently become available. A problem with metal hydride TES systems in the past has been selecting a suitable high capacity low temperature metal hydride material to pair with the high temperature material. A unique aspect of metal hydride TES systems is that many of these systems can be located on or near dish/engine collectors due to their high thermal capacity and small size. The primary objective of this work is to develop a high enthalpy metal hydride that is capable of reversibly storing hydrogen at high temperatures (> 650 °C) and that can be paired with a suitable low enthalpy metal hydride with low cost materials. Furthermore, a demonstration of hydrogen cycling between the two hydride beds is desired.

  5. Zircaloy-4 hydridation

    International Nuclear Information System (INIS)

    Vizcaino, Pablo

    1997-01-01

    The objectives of this work can be summarized as: 1) To reproduce, by heat treatments, matrix microstructures and hydride morphologies similar to those observed in structural components of the CNA-1 and CNE nuclear power plants; 2) To study the evolution of the mechanical properties of the original material with different hydrogen concentrations, such as microhardness, and its capacity to distinguish these materials; 3) To find parameters that allow to estimate the hydrogen content of a material by quantitative metallographic techniques, to be used as complementary in the study of the radioactive materials from reactors

  6. Hydride embrittlement in zircaloy components

    Energy Technology Data Exchange (ETDEWEB)

    Lobo, Raquel M.; Andrade, Arnaldo H.P.; Castagnet, Mariano, E-mail: rmlobo@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2011-07-01

    Zirconium alloys are used in nuclear reactor cores under high-temperature water environment. During service, hydrogen is generated by corrosion processes, and it is readily absorbed by these materials. When hydrogen concentration exceeds the terminal solid solubility, the excess hydrogen precipitates as zirconium hydride (ZrH{sub 2}) platelets or needles. Zirconium alloys components can fail by hydride cracking if they contain large flaws and are highly stressed. Zirconium alloys are susceptible to a mechanism for crack initiation and propagation termed delayed hydride cracking (DHC). The presence of brittle hydrides, with a K{sub Ic} fracture toughness of only a few MPa{radical}m, results in a severe loss in ductility and toughness when platelet normal is oriented parallel to the applied stress. In plate or tubing, hydrides tend to form perpendicular to the thickness direction due to the texture developed during fabrication. Hydrides in this orientation do not generally cause structural problems because applied stresses in the through-thickness direction are very low. However, the high mobility of hydrogen in a zirconium lattice enables redistribution of hydrides normal to the applied stress direction, which can result in localized embrittlement. When a platelet reaches a critical length it ruptures. If the tensile stress is sufficiently great, crack initiation starts at some of these hydrides. Crack propagation occurs by repeating the same process at the crack tip. Delayed hydride cracking can degrade the structural integrity of zirconium alloys during reactor service. The paper focuses on the fracture mechanics and fractographic aspects of hydride material. (author)

  7. in Spouted Bed

    Directory of Open Access Journals (Sweden)

    Bronislaw Buczek

    2013-01-01

    Full Text Available Samples of active coke, fresh and spent after cleaning flue gases from communal waste incinerators, were investigated. The outer layers of both coke particles were separately removed by comminution in a spouted bed. The samples of both active cokes were analysed by means of densities, mercury porosimetry, and adsorption technique. Remaining cores were examined to determine the degree of consumption of coke by the sorption of hazardous emissions (SO2, HCl, and heavy metals through its bed. Differences in contamination levels within the porous structure of the particles were estimated. The study demonstrated the effectiveness of commercial active coke in the cleaning of flue gases.

  8. Anodematerials for Metal Hydride Batteries

    DEFF Research Database (Denmark)

    Jensen, Jens Oluf

    1997-01-01

    This report describes the work on development of hydride forming alloys for use as electrode materials in metal hydride batteries. The work has primarily been concentrated on calcium based alloys derived from the compound CaNi5. This compound has a higher capacity compared with alloys used in today......’s hydride batteries, but a much poorer stability towards repeated charge/discharge cycling. The aim was to see if the cycleability of CaNi5 could be enhanced enough by modifications to make the compound a suitable electrode material. An alloying method based on mechanical alloying in a planetary ball mill...

  9. Erbium hydride decomposition kinetics.

    Energy Technology Data Exchange (ETDEWEB)

    Ferrizz, Robert Matthew

    2006-11-01

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

  10. 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

  11. Complex Hydrides for Hydrogen Storage

    Energy Technology Data Exchange (ETDEWEB)

    Slattery, Darlene; Hampton, Michael

    2003-03-10

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

  12. Hydriding failure in water reactor fuel elements

    International Nuclear Information System (INIS)

    Sah, D.N.; Ramadasan, E.; Unnikrishnan, K.

    1980-01-01

    Hydriding of the zircaloy cladding has been one of the important causes of failure in water reactor fuel elements. This report reviews the causes, the mechanisms and the methods for prevention of hydriding failure in zircaloy clad water reactor fuel elements. The different types of hydriding of zircaloy cladding have been classified. Various factors influencing zircaloy hydriding from internal and external sources in an operating fuel element have been brought out. The findings of post-irradiation examination of fuel elements from Indian reactors, with respect to clad hydriding and features of hydriding failure are included. (author)

  13. Mechanical properties and fracture of titanium hydrides

    International Nuclear Information System (INIS)

    Koketsu, Hideyuki; Taniyama, Yoshihiro; Yonezu, Akio; Cho, Hideo; Ogawa, Takeshi; Takemoto, Mikio; Nakayama, Gen

    2006-01-01

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

  14. High-pressure hydriding of Zircaloy

    International Nuclear Information System (INIS)

    Kim, Y.S.

    1996-01-01

    The hydriding characteristics of Zircaloy-2(Zry), sponge zirconium (as a liner on Zry plate), and crystal-bar zirconium exposed to pure H 2 at 0.1 MPa or 7 MPa and 400 C were determined in a thermogravimetric apparatus. The morphology of the hydrided specimens was also examined by optical microscopy. For all specimen types, the rate of hydriding in 7 MPa H 2 was two orders of magnitude greater than in 0.1 MPa H 2 . For Zry, uniform bulk hydriding was revealed by hydride precipitates at room temperature and on one occasion, a sunburst hydride. In addition, all specimen types exhibited a hydride surface layer. In a duplex Zry/sponge-Zr specimen, Zry is more heavily hydrided than the sponge Zr layer. (orig.)

  15. Hydride Olefin complexes of tantalum and niobium

    NARCIS (Netherlands)

    Klazinga, Aan Hendrik

    1979-01-01

    This thesis describes investigations on low-valent tantalum and niobium hydride and alkyl complexes, particularly the dicyclopentadienyl tantalum hydride olefin complexes Cp2Ta(H)L (L=olefin). ... Zie: Summary

  16. Metal hydride compositions and lithium ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Young, Kwo; Nei, Jean

    2018-04-24

    Heterogeneous metal hydride (MH) compositions comprising a main region comprising a first metal hydride and a secondary region comprising one or more additional components selected from the group consisting of second metal hydrides, metals, metal alloys and further metal compounds are suitable as anode materials for lithium ion cells. The first metal hydride is for example MgH.sub.2. Methods for preparing the composition include coating, mechanical grinding, sintering, heat treatment and quenching techniques.

  17. Sorption compressor/mechanical expander hybrid refrigeration

    Science.gov (United States)

    Jones, J. A.; Britcliffe, M.

    1987-01-01

    Experience with Deep Space Network (DSN) ground-based cryogenic refrigerators has proved the reliability of the basic two-stage Gifford-McMahon helium refrigerator. A very long life cryogenic refrigeration system appears possible by combining this expansion system or a turbo expansion system with a hydride sorption compressor in place of the usual motor driven piston compressor. To test the feasibility of this system, a commercial Gifford-McMahon refrigerator was tested using hydrogen gas as the working fluid. Although no attempt was made to optimize the system for hydrogen operation, the refrigerator developed 1.3 W at 30 K and 6.6 W at 60 K. The results of the test and of theoretical performances of the hybrid compressor coupled to these expansion systems are presented.

  18. Sorption by cation exchange

    International Nuclear Information System (INIS)

    Bradbury, M.H.; Baeyens, B.

    1994-04-01

    A procedure for introducing exchange into geochemical/surface complexation codes is described. Beginning with selectivity coefficients, K c , defined in terms of equivalent fractional ion occupancies, a general expression for the molar based exchange code input parameters, K ex , is derived. In natural systems the uptake of nuclides onto complex sorbents often occurs by more than one mechanism. The incorporation of cation exchange and surface complexation into a geochemical code therefore enables sorption by both mechanisms to be calculated simultaneously. The code and model concepts are tested against sets of experimental data from widely different sorption studies. A proposal is made to set up a data base of selectivity coefficients. Such a data base would form part of a more general one consisting of sorption mechanism specific parameters to be used in conjunction with geochemical/sorption codes to model and predict sorption. (author) 6 figs., 6 tabs., 26 refs

  19. Metal hydrides: an innovative and challenging conversion reaction anode for lithium-ion batteries

    Directory of Open Access Journals (Sweden)

    Luc Aymard

    2015-08-01

    Full Text Available The state of the art of conversion reactions of metal hydrides (MH with lithium is presented and discussed in this review with regard to the use of these hydrides as anode materials for lithium-ion batteries. A focus on the gravimetric and volumetric storage capacities for different examples from binary, ternary and complex hydrides is presented, with a comparison between thermodynamic prediction and experimental results. MgH2 constitutes one of the most attractive metal hydrides with a reversible capacity of 1480 mA·h·g−1 at a suitable potential (0.5 V vs Li+/Li0 and the lowest electrode polarization (2, TiH2, complex hydrides Mg2MHx and other Mg-based hydrides. The reversible conversion reaction mechanism of MgH2, which is lithium-controlled, can be extended to others hydrides as: MHx + xLi+ + xe− in equilibrium with M + xLiH. Other reaction paths—involving solid solutions, metastable distorted phases, and phases with low hydrogen content—were recently reported for TiH2 and Mg2FeH6, Mg2CoH5 and Mg2NiH4. The importance of fundamental aspects to overcome technological difficulties is discussed with a focus on conversion reaction limitations in the case of MgH2. The influence of MgH2 particle size, mechanical grinding, hydrogen sorption cycles, grinding with carbon, reactive milling under hydrogen, and metal and catalyst addition to the MgH2/carbon composite on kinetics improvement and reversibility is presented. Drastic technological improvement in order to the enhance conversion process efficiencies is needed for practical applications. The main goals are minimizing the impact of electrode volume variation during lithium extraction and overcoming the poor electronic conductivity of LiH. To use polymer binders to improve the cycle life of the hydride-based electrode and to synthesize nanoscale composite hydride can be helpful to address these drawbacks. The development of high-capacity hydride anodes should be inspired by the emergent

  20. Metal hydrides: an innovative and challenging conversion reaction anode for lithium-ion batteries.

    Science.gov (United States)

    Aymard, Luc; Oumellal, Yassine; Bonnet, Jean-Pierre

    2015-01-01

    The state of the art of conversion reactions of metal hydrides (MH) with lithium is presented and discussed in this review with regard to the use of these hydrides as anode materials for lithium-ion batteries. A focus on the gravimetric and volumetric storage capacities for different examples from binary, ternary and complex hydrides is presented, with a comparison between thermodynamic prediction and experimental results. MgH2 constitutes one of the most attractive metal hydrides with a reversible capacity of 1480 mA·h·g(-1) at a suitable potential (0.5 V vs Li(+)/Li(0)) and the lowest electrode polarization (lithium are subsequently detailed for MgH2, TiH2, complex hydrides Mg2MH x and other Mg-based hydrides. The reversible conversion reaction mechanism of MgH2, which is lithium-controlled, can be extended to others hydrides as: MH x + xLi(+) + xe(-) in equilibrium with M + xLiH. Other reaction paths-involving solid solutions, metastable distorted phases, and phases with low hydrogen content-were recently reported for TiH2 and Mg2FeH6, Mg2CoH5 and Mg2NiH4. The importance of fundamental aspects to overcome technological difficulties is discussed with a focus on conversion reaction limitations in the case of MgH2. The influence of MgH2 particle size, mechanical grinding, hydrogen sorption cycles, grinding with carbon, reactive milling under hydrogen, and metal and catalyst addition to the MgH2/carbon composite on kinetics improvement and reversibility is presented. Drastic technological improvement in order to the enhance conversion process efficiencies is needed for practical applications. The main goals are minimizing the impact of electrode volume variation during lithium extraction and overcoming the poor electronic conductivity of LiH. To use polymer binders to improve the cycle life of the hydride-based electrode and to synthesize nanoscale composite hydride can be helpful to address these drawbacks. The development of high-capacity hydride anodes should

  1. Bed Bugs

    Science.gov (United States)

    Prevent, identify, and treat bed bug infestations using EPA’s step-by-step guides, based on IPM principles. Find pesticides approved for bed bug control, check out the information clearinghouse, and dispel bed bug myths.

  2. Sorption data bases and mechanistic sorption studies

    International Nuclear Information System (INIS)

    Bradbury, M.H.

    2000-01-01

    In common with many other countries with a nuclear programme, the Swiss concept for the disposal of radioactive waste is focused on deep burial in specially constructed repositories in geologically stable host rocks. Under such conditions, the most likely means whereby radionuclides might return to the biosphere involves their transport in slowly moving groundwater. The sorption of radionuclides by solid phases in the engineered barriers within the repository, and in the surrounding geological media, limits their release and retards their movement. Performance assessment studies for disposal concepts are carried out by Nagra, the National Cooperative for the Disposal of Radioactive Waste, in which various release scenarios are examined, and 'doses to man' calculated. The uptake of radionuclides by immobile phases is one of the pillars upon which the safety case rests. Hence, sorption databases are very important data sets for performance assessments. The methodology lying behind the construction of sorption databases, and some aspects of the supporting experimental work, are briefly described in this report. Flexible, long-term, focused research programmes are required to properly understand the radionuclide/rock/groundwater system, and this is an essential pre-requisite for producing robust state-of-the-art sorption databases. (author)

  3. Sorption data bases and mechanistic sorption studies

    Energy Technology Data Exchange (ETDEWEB)

    Bradbury, M.H

    2000-07-01

    In common with many other countries with a nuclear programme, the Swiss concept for the disposal of radioactive waste is focused on deep burial in specially constructed repositories in geologically stable host rocks. Under such conditions, the most likely means whereby radionuclides might return to the biosphere involves their transport in slowly moving groundwater. The sorption of radionuclides by solid phases in the engineered barriers within the repository, and in the surrounding geological media, limits their release and retards their movement. Performance assessment studies for disposal concepts are carried out by Nagra, the National Cooperative for the Disposal of Radioactive Waste, in which various release scenarios are examined, and 'doses to man' calculated. The uptake of radionuclides by immobile phases is one of the pillars upon which the safety case rests. Hence, sorption databases are very important data sets for performance assessments. The methodology lying behind the construction of sorption databases, and some aspects of the supporting experimental work, are briefly described in this report. Flexible, long-term, focused research programmes are required to properly understand the radionuclide/rock/groundwater system, and this is an essential pre-requisite for producing robust state-of-the-art sorption databases. (author)

  4. Sorption of nitrate onto amine-crosslinked wheat straw: characteristics, column sorption and desorption properties.

    Science.gov (United States)

    Xing, Xu; Gao, Bao-Yu; Zhong, Qian-Qian; Yue, Qin-Yan; Li, Qian

    2011-02-15

    The nitrate removal process was evaluated using a fixed-bed column packed with amine-crosslinked wheat straw (AC-WS). Column sorption and desorption characteristics of nitrate were studied extensively. Solid-state (13)C NMR and zeta potential analysis validated the existence of crosslinked amine groups in AC-WS. Raman shift of the nitrate peaks suggested the electrostatic attraction between the adsorbed ions and positively charged amine sites. The column sorption capacity (q(ed)) of the AC-WS for nitrate was 87.27 mg g(-1) in comparison with the raw WS of 0.57 mg g(-1). Nitrate sorption in column was affected by bed height, influent nitrate concentration, flow rate and pH, and of all these, influent pH demonstrated an essential effect on the performance of the column. In addition, desorption and dynamic elution tests were repeated for several cycles, with high desorption rate and slight losses in its initial column sorption capacity. Copyright © 2010 Elsevier B.V. All rights reserved.

  5. Metal hydride hydrogen compression: recent advances and future prospects

    Science.gov (United States)

    Yartys, Volodymyr A.; Lototskyy, Mykhaylo; Linkov, Vladimir; Grant, David; Stuart, Alastair; Eriksen, Jon; Denys, Roman; Bowman, Robert C.

    2016-04-01

    Metal hydride (MH) thermal sorption compression is one of the more important applications of the MHs. The present paper reviews recent advances in the field based on the analysis of the fundamental principles of this technology. The performances when boosting hydrogen pressure, along with two- and three-step compression units, are analyzed. The paper includes also a theoretical modelling of a two-stage compressor aimed at describing the performance of the experimentally studied systems, their optimization and design of more advanced MH compressors. Business developments in the field are reviewed for the Norwegian company HYSTORSYS AS and the South African Institute for Advanced Materials Chemistry. Finally, future prospects are outlined presenting the role of the MH compression in the overall development of the hydrogen-driven energy systems. The work is based on the analysis of the development of the technology in Europe, USA and South Africa.

  6. Interface Enthalpy-Entropy Competition in Nanoscale Metal Hydrides

    Directory of Open Access Journals (Sweden)

    Nicola Patelli

    2018-01-01

    Full Text Available We analyzed the effect of the interfacial free energy on the thermodynamics of hydrogen sorption in nano-scaled materials. When the enthalpy and entropy terms are the same for all interfaces, as in an isotropic bi-phasic system, one obtains a compensation temperature, which does not depend on the system size nor on the relative phase abundance. The situation is different and more complex in a system with three or more phases, where the interfaces have different enthalpy and entropy. We also consider the possible effect of elastic strains on the stability of the hydride phase and on hysteresis. We compare a simple model with experimental data obtained on two different systems: (1 bi-phasic nanocomposites where ultrafine TiH2 crystallite are dispersed within a Mg nanoparticle and (2 Mg nanodots encapsulated by different phases.

  7. Predicting Hydride Donor Strength via Quantum Chemical Calculations of Hydride Transfer Activation Free Energy.

    Science.gov (United States)

    Alherz, Abdulaziz; Lim, Chern-Hooi; Hynes, James T; Musgrave, Charles B

    2018-01-25

    We propose a method to approximate the kinetic properties of hydride donor species by relating the nucleophilicity (N) of a hydride to the activation free energy ΔG ⧧ of its corresponding hydride transfer reaction. N is a kinetic parameter related to the hydride transfer rate constant that quantifies a nucleophilic hydridic species' tendency to donate. Our method estimates N using quantum chemical calculations to compute ΔG ⧧ for hydride transfers from hydride donors to CO 2 in solution. A linear correlation for each class of hydrides is then established between experimentally determined N values and the computationally predicted ΔG ⧧ ; this relationship can then be used to predict nucleophilicity for different hydride donors within each class. This approach is employed to determine N for four different classes of hydride donors: two organic (carbon-based and benzimidazole-based) and two inorganic (boron and silicon) hydride classes. We argue that silicon and boron hydrides are driven by the formation of the more stable Si-O or B-O bond. In contrast, the carbon-based hydrides considered herein are driven by the stability acquired upon rearomatization, a feature making these species of particular interest, because they both exhibit catalytic behavior and can be recycled.

  8. Sorption properties of wool

    Directory of Open Access Journals (Sweden)

    Radetić Maja M.

    2004-01-01

    Full Text Available Strict ecological legislation, especially in highly developed countries, imposed requirements for the purification of industrial effluents and the need for efficient oil clean up after sea and inland water spills. Although numerous processes have been developed, the application of sorbents is still one of the most efficient methods to remove heavy metal ions, dyes and crude oil from water. Recently, special attention was paid to sorbents based on natural fibres. A review of studies concerning the sorption properties of wool is presented in this paper. The presence of various functional groups on the wool fibre surface contributes to the efficient sorption of heavy metal ions and dyes. A hydrophobic, scaly surface and fibre crimp strongly influence the high sorption capacity of wool for oil. Wool has great sorption potential even as a recycled material. Accordingly, it can be used as a viable substitute to commercially available synthetic sorbents that show poor biodegradab ility.

  9. Permeation rates for RTF metal hydride vessels

    International Nuclear Information System (INIS)

    Klein, J.E.

    1992-01-01

    Contamination rates have been estimated for the RTF nitrogen heating and cooling system (NH and CS) due to tritium permeation through the walls of metal hydride vessels. Tritium contamination of the NH and CS will be seen shortly after start-up of the RTF with the majority of it coming from the TCAP units. Contamination rates of the NH and CS are estimated to exceed 400 Ci/year after three years of operation and will elevate tritium concentrations in the NH and CS above 6 x 10 -3 μCi/cc. To reduce tritium activity in the NH and CS, a stripper or ''getter'' bed may need to be installed in the NH and CS. Increasing the purge rate of nitrogen from the NH and CS is shown to be an impractical method for reducing tritium activity due to the high purge rates required. Stripping of the NH and CS nitrogen in the glove box stripper system will give a temporary lowering of tritium activity in the NH and CS, but tritium activity will return to its previous level in approximately two weeks

  10. Tritium processing using metal hydrides

    International Nuclear Information System (INIS)

    Mallett, M.W.

    1986-01-01

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

  11. Hydride Molecules towards Nearby Galaxies

    Science.gov (United States)

    Monje, Raquel R.; La, Ngoc; Goldsmith, Paul

    2018-06-01

    Observations carried out by the Herschel Space Observatory revealed strong spectroscopic signatures from light hydride molecules within the Milky Way and nearby active galaxies. To better understand the chemical and physical conditions of the interstellar medium, we conducted the first comprehensive survey of hydrogen fluoride (HF) and water molecular lines observed through the SPIRE Fourier Transform Spectrometer. By collecting and analyzing the sub-millimeter spectra of over two hundred sources, we found that the HF J = 1 - 0 rotational transition which occurs at approximately 1232 GHz was detected in a total of 39 nearby galaxies both in absorption and emission. The analysis will determine the main excitation mechanism of HF in nearby galaxies and provide steady templates of the chemistry and physical conditions of the ISM to be used in the early universe, where observations of hydrides are more scarce.

  12. Rechargeable metal hydrides for spacecraft application

    Science.gov (United States)

    Perry, J. L.

    1988-01-01

    Storing hydrogen on board the Space Station presents both safety and logistics problems. Conventional storage using pressurized bottles requires large masses, pressures, and volumes to handle the hydrogen to be used in experiments in the U.S. Laboratory Module and residual hydrogen generated by the ECLSS. Rechargeable metal hydrides may be competitive with conventional storage techniques. The basic theory of hydride behavior is presented and the engineering properties of LaNi5 are discussed to gain a clear understanding of the potential of metal hydrides for handling spacecraft hydrogen resources. Applications to Space Station and the safety of metal hydrides are presented and compared to conventional hydride storage. This comparison indicates that metal hydrides may be safer and require lower pressures, less volume, and less mass to store an equivalent mass of hydrogen.

  13. Complex hydrides for hydrogen storage

    Science.gov (United States)

    Zidan, Ragaiy

    2006-08-22

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

  14. Nanostructured, complex hydride systems for hydrogen generation

    Directory of Open Access Journals (Sweden)

    Robert A. Varin

    2015-02-01

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

  15. Use of reversible hydrides for hydrogen storage

    Science.gov (United States)

    Darriet, B.; Pezat, M.; Hagenmuller, P.

    1980-01-01

    The addition of metals or alloys whose hydrides have a high dissociation pressure allows a considerable increase in the hydrogenation rate of magnesium. The influence of temperature and hydrogen pressure on the reaction rate were studied. Results concerning the hydriding of magnesium rich alloys such as Mg2Ca, La2Mg17 and CeMg12 are presented. The hydriding mechanism of La2Mg17 and CeMg12 alloys is given.

  16. NMR study of hydride systems

    International Nuclear Information System (INIS)

    Peretz, M.

    1980-02-01

    The hydrides of thorium (ThH 2 , Th 4 H 15 and Th 4 D 15 ) and the intermetallic compound system (Zr(Vsub(1-x)Cosub(x)) 2 and its hydrides were investigated using the nuclear magnetic resonance (NMR) technique. From the results for the thorium hydride samples it was concluded that the density of states at the Fermi level n(Esub(f)) is higher in Th 4 H 15 than in ThH 2 ; there is an indirect reaction between the protons and the d electrons belonging to the Th atoms in Th 4 H 15 ; n(E) has a sharp structure near Esub(f). It was also found that the hydrogen diffusion mechanism changes with temperature. From the results for the intermetallic compound system conclusions were drawn concerning variations in the electronic structure, which explain the behavior of the system. In hydrogen diffusion studies in several samples it was found that Co atoms slow the diffusion rate. Quadrupole spectra obtained at low temperatures show that the H atoms preferably occupy tetrahedral sites formed by three V atoms and one Z atom. (H.K.)

  17. Fundamental experiments on hydride reorientation in zircaloy

    Science.gov (United States)

    Colas, Kimberly B.

    In the current study, an in-situ X-ray diffraction technique using synchrotron radiation was used to follow directly the kinetics of hydride dissolution and precipitation during thermomechanical cycles. This technique was combined with conventional microscopy (optical, SEM and TEM) to gain an overall understanding of the process of hydride reorientation. Thus this part of the study emphasized the time-dependent nature of the process, studying large volume of hydrides in the material. In addition, a micro-diffraction technique was also used to study the spatial distribution of hydrides near stress concentrations. This part of the study emphasized the spatial variation of hydride characteristics such as strain and morphology. Hydrided samples in the shape of tensile dog-bones were used in the time-dependent part of the study. Compact tension specimens were used during the spatial dependence part of the study. The hydride elastic strains from peak shift and size and strain broadening were studied as a function of time for precipitating hydrides. The hydrides precipitate in a very compressed state of stress, as measured by the shift in lattice spacing. As precipitation proceeds the average shift decreases, indicating average stress is reduced, likely due to plastic deformation and morphology changes. When nucleation ends the hydrides follow the zirconium matrix thermal contraction. When stress is applied below the threshold stress for reorientation, hydrides first nucleate in a very compressed state similar to that of unstressed hydrides. After reducing the average strain similarly to unstressed hydrides, the average hydride strain reaches a constant value during cool-down to room temperature. This could be due to a greater ease of deforming the matrix due to the applied far-field strain which would compensate for the strains due to thermal contraction. Finally when hydrides reorient, the average hydride strains become tensile during the first precipitation regime and

  18. Metal sorption on kaolinite

    International Nuclear Information System (INIS)

    Westrich, H.R.; Brady, P.V.; Cygan, R.T.; Nagy, K.L.; Anderson, H.L.

    1997-01-01

    A key issue in performance assessment of low-level radioactive waste sites is predicting the transport and retardation of radionuclides through local soils under a variety of hydrologic and geochemical conditions. Improved transport codes should include a mechanistic model of radionuclide retardation. The authors have been investigating metal sorption (Cs + , Sr 2+ , and Ba 2+ ) on a simple clay mineral (kaolinite) to better understand the geochemical interactions of common soil minerals with contaminated groundwaters. These studies include detailed characterizations of kaolinite surfaces, experimental adsorption measurements, surface complexation modeling, and theoretical simulations of cation sorption. The aluminol edge (010) site has been identified as the most likely site for metal sorption on kaolinite in natural solutions. Relative metal binding strengths decrease from Ba 2+ to Sr 2+ to Cs + , with some portion sorbed on both kaolinite edges and basal surfaces. Some Cs + also appears to be irreversibly sorbed on both sites. Molecular dynamics simulations suggest that Cs + is sorbed at aluminol (010) edge sites as an inner-sphere complex and weakly sorbed as an outer-sphere complex on (001) basal surfaces. These results provide the basis to understand and predict metal sorption onto kaolinite, and a framework to characterize sorption processes on more complex clay minerals

  19. Manufacture of titanium and zirconium hydrides

    International Nuclear Information System (INIS)

    Mares, F.; Hanslik, T.

    1973-01-01

    A method is described of manufacturing titanium and zirconium hydrides by hydrogenation of said metals characterized by the reaction temperature ranging between 250 to 500 degC, hydrogen pressure of 20 to 300 atm and possibly by the presence of a hydride of the respective metal. (V.V.)

  20. Hydride effect on crack instability of Zircaloy cladding

    Energy Technology Data Exchange (ETDEWEB)

    Tseng, Che-Chung, E-mail: cctseng@iner.gov.tw [Institute of Nuclear Energy Research, No. 1000, Wunhua Road, Jiaan Village, Lungtan, Township, Taoyuan County 32546, Taiwan (China); Sun, Ming-Hung [Institute of Nuclear Energy Research, No. 1000, Wunhua Road, Jiaan Village, Lungtan, Township, Taoyuan County 32546, Taiwan (China); Chao, Ching-Kong [Department of Mechanical Engineering, National Taiwan University of Science and Technology, 43 Keelung Road, Section 4, Taipei 106, Taiwan (China)

    2014-04-01

    Highlights: • Radial hydrides near the crack tip had a significant effect on crack propagation. • For radial hydrides off the crack line vertically, the effect on crack propagation was notably reduced. • The longer hydride platelet resulted in a remarkable effect on crack propagation. • A long split in the radial hydride precipitate would enhance crack propagation. • The presence of circumferential hydride among radial hydrides may play an important role in crack propagation. - Abstract: A methodology was proposed to investigate the effect of hydride on the crack propagation in fuel cladding. The analysis was modeled based on an outside-in crack with radial hydrides located near its crack tip. The finite element method was used in the calculation; both stress intensity factor K{sub I} and J integral were applied to evaluate the crack stability. The parameters employed in the analysis included the location of radial hydride, hydride dimensions, number of hydrides, and the presence of circumferential hydride, etc. According to our study, the effective distance between a radial hydride and the assumed cladding surface crack for the enhancement of crack propagation proved to be no greater than 0.06 mm. For a hydride not on the crack line, it would induce a relatively minor effect on crack propagation if the vertical distance was beyond 0.05 mm. However, a longer hydride precipitate as well as double radial hydrides could have a remarkable effect on crack propagation. A combined effect of radial and circumferential hydrides was also discussed.

  1. Obtaining zircaloy powder through hydriding

    International Nuclear Information System (INIS)

    Dupim, Ivaldete da Silva; Moreira, Joao M.L.

    2009-01-01

    Zirconium alloys are good options for the metal matrix in dispersion fuels for power reactors due to their low thermal neutron absorption cross-section, good corrosion resistance, good mechanical strength and high thermal conductivity. A necessary step for obtaining such fuels is producing Zr alloy powder for the metal matrix composite material. This article presents results from the Zircaloy-4 hydrogenation tests with the purpose to embrittle the alloy as a first step for comminuting. Several hydrogenation tests were performed and studied through thermogravimetric analysis. They included H 2 pressures of 25 and 50 kPa and temperatures ranging between from 20 to 670 deg C. X-ray diffraction analysis showed in the hydrogenated samples the predominant presence of ZrH 2 and some ZrO 2 . Some kinetics parameters for the Zircaloy-4 hydrogenation reaction were obtained: the time required to reach the equilibrium state at the dwell temperature was about 100 minutes; the hydrogenation rate during the heating process from 20 to 670 deg C was about 21 mg/h, and at constant temperature of 670 deg C, the hydride rate was about 1.15 mg/h. The hydrogenation rate is largest during the heating process and most of it occurs during this period. After hydrogenated, the samples could easily be comminuted indicating that this is a possible technology to obtain Zircaloy powder. The results show that only few minutes of hydrogenation are necessary to reach the hydride levels required for comminuting the Zircaloy. The final hydride stoichiometry was between 2.7 and 2.8 H for each Zr atom in the sample (author)

  2. Zirconium hydride containing explosive composition

    Science.gov (United States)

    Walker, Franklin E.; Wasley, Richard J.

    1981-01-01

    An improved explosive composition is disclosed and comprises a major portion of an explosive having a detonation velocity between about 1500 and 10,000 meters per second and a minor amount of a donor additive comprising a non-explosive compound or mixture of non-explosive compounds which when subjected to an energy fluence of 1000 calories/cm.sup.2 or less is capable of releasing free radicals each having a molecular weight between 1 and 120. Exemplary donor additives are dibasic acids, polyamines and metal hydrides.

  3. Generalized computational model for high-pressure metal hydrides with variable thermal properties

    DEFF Research Database (Denmark)

    Mazzucco, Andrea; Rokni, Masoud

    2015-01-01

    This study considers a detailed 1D fueling model applied to a metal hydride system, with Ti1.1CrMn as the absorbing alloy, to predict the weight fraction of the absorbed hydrogen and the solid bed temperature. Dependencies of thermal conductivity and specific heat capacity upon pressure...... is estimated to be approximately 10%. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved....

  4. Sorption of radon-222 to natural sediments

    International Nuclear Information System (INIS)

    Wong, C.S.; Chin, Y.P.; Gschwend, P.M.

    1992-01-01

    The sorption of radon to sediments was investigated, since this may affect the use of porewater radon profiles for estimating bed irrigation rates. Batch experiments showed that radon has an organic-carbon-normalized sediment-water partition coefficient (K oc , L kg oc -1 ) of 21.1 ± 2.9 for a Boston Harbor sediment, 25.3 ± 2.1 for a Charles River sediment, and 22.4 ± 2.6 for a Buzzards Bay sediment. These values are in close agreement with predictions using radon's octanol-water partition coefficient (K ow ), which was measured to be 32.4 ± 1.5. Temperature and ionic strength effects on K oc were estimated to be small. Given rapid sorption kinetics, the authors suggest that slurry stripping techniques used by many investigators to measure 222 Rn in sediment samples collect both sorbed and dissolved radon. Sorption effects were included in a transport model to obtain revised estimates of irrigation rates from existing literature profiles. Irrigation rates had to be increased over previously reported values in proportion to the sediment organic matter content

  5. Metal Hydrides for Rechargeable Batteries

    Energy Technology Data Exchange (ETDEWEB)

    Valoeen, Lars Ole

    2000-03-01

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

  6. Activated aluminum hydride hydrogen storage compositions and uses thereof

    Science.gov (United States)

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

    2010-11-23

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

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

    DEFF Research Database (Denmark)

    Johansson, Martin; Skulason, Egill; Nielsen, Gunver

    2010-01-01

    strongly to Pd hydride than to Pd. The activation barrier for desorption at a H coverage of one mono layer is slightly lower on Pd hydride, whereas the activation energy for adsorption is similar on Pd and Pd hydride. It is concluded that the higher sticking probability on Pd hydride is most likely caused...

  8. Cyclopentadiene-mediated hydride transfer from rhodium complexes.

    Science.gov (United States)

    Pitman, C L; Finster, O N L; Miller, A J M

    2016-07-12

    Attempts to generate a proposed rhodium hydride catalytic intermediate instead resulted in isolation of (Cp*H)Rh(bpy)Cl (1), a pentamethylcyclopentadiene complex, formed by C-H bond-forming reductive elimination from the fleeting rhodium hydride. The hydride transfer ability of diene 1 was explored through thermochemistry and hydride transfer reactions, including the reduction of NAD(+).

  9. Identification and characterization of a new Zirconium hydride

    International Nuclear Information System (INIS)

    Zhao, Z.

    2007-01-01

    In order to control the integrity of the fuel clad, alloy of zirconium, it is necessary to predict the behavior of zirconium hydrides in the environment (temperature, stress...), at a microscopic scale. A characterization study by TEM of hydrides has been realized. It shows little hydrides about 500 nm, in hydride Zircaloy 4. Then a more detailed study identified a new hydride phase presented in this paper. (A.L.B.)

  10. Hydride heat pump with heat regenerator

    Science.gov (United States)

    Jones, Jack A. (Inventor)

    1991-01-01

    A regenerative hydride heat pump process and system is provided which can regenerate a high percentage of the sensible heat of the system. A series of at least four canisters containing a lower temperature performing hydride and a series of at least four canisters containing a higher temperature performing hydride is provided. Each canister contains a heat conductive passageway through which a heat transfer fluid is circulated so that sensible heat is regenerated. The process and system are useful for air conditioning rooms, providing room heat in the winter or for hot water heating throughout the year, and, in general, for pumping heat from a lower temperature to a higher temperature.

  11. A procedure for preparing alkali metal hydrides

    International Nuclear Information System (INIS)

    Lemieux, R.U.; Sanford, C.E.; Prescott, J.F.

    1976-01-01

    A plain low cost, procedure for the continuous, low temperature preparation of sodium or potassium hydrides using cheap reagents is presented. Said invention is especially concerned with a process of purifying of a catalytic exchange liquid used for deuterium enrichment, in which an alkali metal hydride is produced as intermediate product. The procedure for producing the sodium and potassium hydrides consists in causing high pressure hydrogen to be absorbed by a mixture of at least a lower monoalkylamine and an alkylamide of an alkali metal from at least one of said amines [fr

  12. Hydride observations using the neutrography technique

    International Nuclear Information System (INIS)

    Meyer, G.; Baruj, A.; Borzone, E.M.; Cardenas, R.; Szames, E.; Somoza, J.; Rivas, S.; Sanchez, F.A.; Marin, J.

    2012-01-01

    Neutron radiography observations were performed at the RA-6 experimental nuclear facility in Bariloche. Images from a prototype of a hydride-based hydrogen storage device have been obtained. The technique allows visualizing the inner hydride space distribution. The hydride appeared compacted at the lower part of the prototype after several cycles of hydrogen charge and discharge. The technique has also been applied to the study of Zr/ZrH 2 samples. There is a linear relation between the sample width/hydrogen concentration and the photograph grey scale. This information could be useful for the study of nuclear engineering materials and to determine their possible degradation by hydrogen pick up (author)

  13. 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.

  14. The Oxidation Products of Aluminum Hydride and Boron Aluminum Hydride Clusters

    Science.gov (United States)

    2016-01-04

    AFRL-AFOSR-VA-TR-2016-0075 The Oxidation Products of Aluminum Hydride and Boron Aluminum Hydride Clusters KIT BOWEN JOHNS HOPKINS UNIV BALTIMORE MD...2. REPORT TYPE Final Performance 3. DATES COVERED (From - To) 30-09-2014 to 29-09-2015 4. TITLE AND SUBTITLE The Oxidation Products of Aluminum ...Hydride and Boron Aluminum Hydride Clusters 5a.  CONTRACT NUMBER 5b.  GRANT NUMBER FA9550-14-1-0324 5c.  PROGRAM ELEMENT NUMBER 61102F 6. AUTHOR(S) KIT

  15. Technetium Sorption Media Review

    International Nuclear Information System (INIS)

    Duncan, J.B.; Kelly, S.E.; Robbins, R.A.; Adams, R.D.; Thorson, M.A.; Haass, C.C.

    2011-01-01

    This report presents information and references to aid in the selection of 99Tc sorption media for feasibility studies regarding the removal of 99Tc from Hanford's low activity waste. The report contains literature search material for sorption media (including ion exchange media) for the most tested media to date, including SuperLig 639, Reillex HPQ, TAM (Kruion), Purolite A520E and A530E, and Dowex 1X8. The U.S. Department of Energy (DOE), Office of River Protection (ORP) is responsible for management and completion of the River Protection Project (RPP) mission, which comprises both the Hanford Site tank farms and the Waste Treatment and Immobilization Plant (WTP). The RPP mission is to store, retrieve and treat Hanford's tank waste; store and dispose of treated wastes; and close the tank farm waste management areas and treatment facilities in a safe, environmentally compliant, cost-effective and energy-effective manner.

  16. TECHNETIUM SORPTION MEDIA REVIEW

    Energy Technology Data Exchange (ETDEWEB)

    DUNCAN JB; KELLY SE; ROBBINS RA; ADAMS RD; THORSON MA; HAASS CC

    2011-08-25

    This report presents information and references to aid in the selection of 99Tc sorption media for feasibility studies regarding the removal of 99Tc from Hanford's low activity waste. The report contains literature search material for sorption media (including ion exchange media) for the most tested media to date, including SuperLig 639, Reillex HPQ, TAM (Kruion), Purolite A520E and A530E, and Dowex 1X8. The U.S. Department of Energy (DOE), Office of River Protection (ORP) is responsible for management and completion of the River Protection Project (RPP) mission, which comprises both the Hanford Site tank farms and the Waste Treatment and Immobilization Plant (WTP). The RPP mission is to store, retrieve and treat Hanford's tank waste; store and dispose of treated wastes; and close the tank farm waste management areas and treatment facilities in a safe, environmentally compliant, cost-effective and energy-effective manner.

  17. Tritium removal using vanadium hydride

    International Nuclear Information System (INIS)

    Hill, F.B.; Wong, Y.W.; Chan, Y.N.

    1978-01-01

    The results of an initial examination of the feasibility of separation of tritium from gaseous protium-tritium mixtures using vanadium hydride in cyclic processes is reported. Interest was drawn to the vanadium-hydrogen system because of the so-called inverse isotope effect exhibited by this system. Thus the tritide is more stable than the protide, a fact which makes the system attractive for removal of tritium from a mixture in which the light isotope predominates. The initial results of three phases of the research program are reported, dealing with studies of the equilibrium and kinetics properties of isotope exchange, development of an equilibrium theory of isotope separation via heatless adsorption, and experiments on the performance of a single heatless adsorption stage. In the equilibrium and kinetics studies, measurements were made of pressure-composition isotherms, the HT--H 2 separation factors and rates of HT--H 2 exchange. This information was used to evaluate constants in the theory and to understand the performance of the heatless adsorption experiments. A recently developed equilibrium theory of heatless adsorption was applied to the HT--H 2 separation using vanadium hydride. Using the theory it was predicted that no separation would occur by pressure cycling wholly within the β phase but that separation would occur by cycling between the β and γ phases and using high purge-to-feed ratios. Heatless adsorption experiments conducted within the β phase led to inverse separations rather than no separation. A kinetic isotope effect may be responsible. Cycling between the β and γ phases led to separation but not to the predicted complete removal of HT from the product stream, possibly because of finite rates of exchange. Further experimental and theoretical work is suggested which may ultimately make possible assessment of the feasibility and practicability of hydrogen isotope separation by this approach

  18. Method of making alkali metal hydrides

    Science.gov (United States)

    Pecharsky, Vitalij K.; Gupta, Shalabh; Pruski, Marek; Hlova, Ihor; Castle, Andra

    2017-05-30

    A method is provided for making alkali metal hydrides by mechanochemically reacting alkali metal and hydrogen gas under mild temperature (e.g room temperature) and hydrogen pressure conditions without the need for catalyst, solvent, and intentional heating or cooling.

  19. Predicting formation enthalpies of metal hydrides

    Energy Technology Data Exchange (ETDEWEB)

    Andreasen, A.

    2004-12-01

    In order for the hydrogen based society viz. a society in which hydrogen is the primary energy carrier to become realizable an efficient way of storing hydrogen is required. For this purpose metal hydrides are serious candidates. Metal hydrides are formed by chemical reaction between hydrogen and metal and for the stable hydrides this is associated with release of heat ({delta}H{sub f} ). The more thermodynamically stable the hydride, the larger {delta}H{sub f}, and the higher temperature is needed in order to desorp hydrogen (reverse reaction) and vice versa. For practical application the temperature needed for desorption should not be too high i.e. {delta}H{sub f} should not be too large. If hydrogen desorption is to be possible below 100 deg C (which is the ultimate goal if hydrogen storage in metal hydrides should be used in conjunction with a PEM fuel cell), {delta}H{sub f} should not exceed -48 kJ/mol. Until recently only intermetallic metal hydrides with a storage capacity less than 2 wt.% H{sub 2} have met this criterion. However, discovering reversible hydrogen storage in complex metal hydrides such as NaAlH{sub 4} (5.5 wt. % reversible hydrogen capacity) have revealed a new group of potential candiates. However, still many combination of elements from the periodic table are yet to be explored. Since experimental determination of thermodynamic properties of the vast combinations of elements is tedious it may be advantagous to have a predictive tool for this task. In this report different ways of predicting {delta}H{sub f} for binary and ternary metal hydrides are reviewed. Main focus will be on how well these methods perform numerically i.e. how well experimental results are resembled by the model. The theoretical background of the different methods is only briefly reviewed. (au)

  20. Sorption of actinides onto nanodiamonds

    Energy Technology Data Exchange (ETDEWEB)

    Buchatskaya, Yulia; Romanchuk, Anna; Yakovlev, Ruslan; Kulakova, Inna [Lomonosov Moscow State Univ., Moscow (Russian Federation). Dept. of Chemistry; Shiryaev, Andrei [Russian Academy of Sciences, Moscow (Russian Federation). Frumkin Institute of Physical Chemistry and Electrochemistry; Russian Academy of Sciences, Moscow (Russian Federation). Inst. of Geology of Ore Deposits, Petrography, Mineralogy and Geochemistry; Kalmykov, Stepan [Lomonosov Moscow State Univ., Moscow (Russian Federation). Dept. of Chemistry; Russian Academy of Sciences, Moscow (Russian Federation). Frumkin Institute of Physical Chemistry and Electrochemistry; Russian Academy of Sciences, Moscow (Russian Federation). Vernadsky Institute of Geochemistry and Analytical Chemistry

    2015-06-01

    Detonation nanodiamonds (ND) present a significant part of nanocarbons group, which could be produced on commercial scale by detonation of explosives in a closed chamber. Their unique properties of high surface area, low weight and radiation resistance make ND a prospective candidate for applications in sorption processes in radiochemistry. To study the influence of surface chemistry on sorption properties, apristine sample of ND was treated with acids and hydrogen. The surface chemistry of the samples was characterised by infrared spectroscopy, X-ray photoelectron spectroscopy and Boehm titration. The sorption properties of ND were tested fordifferent radionuclides. The sorption capacity of ND was shown to be higher than those of commonly used radionuclide sorbents like activated carbon and compariable to other members of nanocarbon group like graphene oxide and carbon nanotubes. The sorption properties were shown to be influenced by the presence of oxygen-containing groups on the surface of ND. This represents an opportunity to increase the sorption capacity of ND.

  1. Sorption of actinides onto nanodiamonds

    International Nuclear Information System (INIS)

    Buchatskaya, Yulia; Romanchuk, Anna; Yakovlev, Ruslan; Kulakova, Inna; Shiryaev, Andrei; Russian Academy of Sciences, Moscow; Kalmykov, Stepan; Russian Academy of Sciences, Moscow; Russian Academy of Sciences, Moscow

    2015-01-01

    Detonation nanodiamonds (ND) present a significant part of nanocarbons group, which could be produced on commercial scale by detonation of explosives in a closed chamber. Their unique properties of high surface area, low weight and radiation resistance make ND a prospective candidate for applications in sorption processes in radiochemistry. To study the influence of surface chemistry on sorption properties, apristine sample of ND was treated with acids and hydrogen. The surface chemistry of the samples was characterised by infrared spectroscopy, X-ray photoelectron spectroscopy and Boehm titration. The sorption properties of ND were tested fordifferent radionuclides. The sorption capacity of ND was shown to be higher than those of commonly used radionuclide sorbents like activated carbon and compariable to other members of nanocarbon group like graphene oxide and carbon nanotubes. The sorption properties were shown to be influenced by the presence of oxygen-containing groups on the surface of ND. This represents an opportunity to increase the sorption capacity of ND.

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

    International Nuclear Information System (INIS)

    Racine, A.

    2005-09-01

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

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

    DEFF Research Database (Denmark)

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

    1975-01-01

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

  4. Method of burning sulfur-containing fuels in a fluidized bed boiler

    Science.gov (United States)

    Jones, Brian C.

    1982-01-01

    A method of burning a sulfur-containing fuel in a fluidized bed of sulfur oxide sorbent wherein the overall utilization of sulfur oxide sorbent is increased by comminuting the bed drain solids to a smaller average particle size, preferably on the order of 50 microns, and reinjecting the comminuted bed drain solids into the bed. In comminuting the bed drain solids, particles of spent sulfur sorbent contained therein are fractured thereby exposing unreacted sorbent surface. Upon reinjecting the comminuted bed drain solids into the bed, the newly-exposed unreacted sorbent surface is available for sulfur oxide sorption, thereby increasing overall sorbent utilization.

  5. The Effect of Hydrogen and Hydrides on the Integrity of Zirconium Alloy Components Delayed Hydride Cracking

    CERN Document Server

    Puls, Manfred P

    2012-01-01

    By drawing together the current theoretical and experimental understanding of the phenomena of delayed hydride cracking (DHC) in zirconium alloys, The Effect of Hydrogen and Hydrides on the Integrity of Zirconium Alloy Components: Delayed Hydride Cracking provides a detailed explanation focusing on the properties of hydrogen and hydrides in these alloys. Whilst the focus lies on zirconium alloys, the combination of both the empirical and mechanistic approaches creates a solid understanding that can also be applied to other hydride forming metals.   This up-to-date reference focuses on documented research surrounding DHC, including current methodologies for design and assessment of the results of periodic in-service inspections of pressure tubes in nuclear reactors. Emphasis is placed on showing that our understanding of DHC is supported by progress across a broad range of fields. These include hysteresis associated with first-order phase transformations; phase relationships in coherent crystalline metallic...

  6. Effect of variable thermal conductivity and specific heat capacity on the calculation of the critical metal hydride thickness for Ti1.1CrMn

    DEFF Research Database (Denmark)

    Mazzucco, Andrea; Rokni, Masoud

    2014-01-01

    model is applied to the metal hydride system, with Ti 1.1 CrMn as the absorbing alloy, to predict the weight fraction of absorbed hydrogen and solid bed temperat ure . Dependencies of thermal conductivity and specific heat capacity upon pressure and hydrogen content respectively , are accounted for...

  7. Synthesis of Nano-Light Magnesium Hydride for Hydrogen Storage ...

    African Journals Online (AJOL)

    Abstract. Nano-light magnesium hydride that has the capability for hydrogen storage was synthesized from treatment of magnesium ribbon with hydrogen peroxide. The optimum time for complete hydrogenation of the magnesium hydride was 5 hours.

  8. High H⁻ ionic conductivity in barium hydride.

    Science.gov (United States)

    Verbraeken, Maarten C; Cheung, Chaksum; Suard, Emmanuelle; Irvine, John T S

    2015-01-01

    With hydrogen being seen as a key renewable energy vector, the search for materials exhibiting fast hydrogen transport becomes ever more important. Not only do hydrogen storage materials require high mobility of hydrogen in the solid state, but the efficiency of electrochemical devices is also largely determined by fast ionic transport. Although the heavy alkaline-earth hydrides are of limited interest for their hydrogen storage potential, owing to low gravimetric densities, their ionic nature may prove useful in new electrochemical applications, especially as an ionically conducting electrolyte material. Here we show that barium hydride shows fast pure ionic transport of hydride ions (H(-)) in the high-temperature, high-symmetry phase. Although some conductivity studies have been reported on related materials previously, the nature of the charge carriers has not been determined. BaH2 gives rise to hydride ion conductivity of 0.2 S cm(-1) at 630 °C. This is an order of magnitude larger than that of state-of-the-art proton-conducting perovskites or oxide ion conductors at this temperature. These results suggest that the alkaline-earth hydrides form an important new family of materials, with potential use in a number of applications, such as separation membranes, electrochemical reactors and so on.

  9. Economic analysis of hydride fueled BWR

    International Nuclear Information System (INIS)

    Ganda, F.; Shuffler, C.; Greenspan, E.; Todreas, N.

    2009-01-01

    The economic implications of designing BWR cores with hydride fuels instead of conventional oxide fuels are analyzed. The economic analysis methodology adopted is based on the lifetime levelized cost of electricity (COE). Bracketing values (1970 and 3010 $/kWe) are used for the overnight construction costs and for the power scaling factors (0.4 and 0.8) that correlate between a change in the capital cost to a change in the power level. It is concluded that a newly constructed BWR reactor could substantially benefit from the use of 10 x 10 hydride fuel bundles instead of 10 x 10 oxide fuel bundles design presently in use. The cost saving would depend on the core pressure drop constraint that can be implemented in newly constructed BWRs - it is between 2% and 3% for a core pressure drop constraint as of the reference BWR, between 9% and 15% for a 50% higher core pressure drop, and between 12% and 21% higher for close to 100% core pressure. The attainable cost reduction was found insensitive to the specific construction cost but strongly dependent on the power scaling factor. The cost advantage of hydride fuelled cores as compared to that of the oxide reference core depends only weakly on the uranium and SWU prices, on the 'per volume base' fabrication cost of hydride fuels, and on the discount rate used. To be economically competitive, the uranium enrichment required for the hydride fuelled core needs to be around 10%.

  10. Experimental investigation of strain, damage and failure of hydrided zircaloy-4 with various hydride orientations

    International Nuclear Information System (INIS)

    Racine, A; Catherine, C.S.; Cappelaere, C.; Bornert, M.; Caldemaison, D.

    2005-01-01

    This experimental investigation is devoted to the influence of the orientation of hydrides on the mechanical response of Zircaloy-4. Ring tensile tests are performed on unirradiated CWSR Zircaloy-4, charged with about 200 or 500wppm hydrogen. Hydrides are oriented either parallel ('tangential'), or perpendicular ('radial') to the circumferential tensile direction. Tangential hydrides are usually observed in cladding tubes, however, hydrides can be reoriented after cooling under stress to become radial and then trigger brittle behavior. In this investigation, we perform, 'macroscopic' or SEM in-situ tensile tests on smooth rings, at room temperature. We get the mechanical response of the material as a function of hydride orientation and hydrogen content and we investigate the deformation, damage and failure mechanisms. In both cases, digital image correlation techniques are used to estimate local and global strain distributions. The results lead to the following conclusions: neither the tensile stress-strain response nor the strain modes are affected by hydrogen content or hydride orientation, but the failure modes are. Indeed, only 200wppm radial hydrides embrittle Zy-4: sample fails in the elastic domain at about 350 MPa before strain bands could develop; whereas in other cases samples reach at least 750 MPa before failure, with ductile or brittle mode. (authors)

  11. Hydrogen storage in complex hydrides

    International Nuclear Information System (INIS)

    Lupu, D.; Biris, A. R.; Misan, I.

    2005-01-01

    Full text: Hydrogen storage is a key enabling technology for the advancement of hydrogen and fuel cell power technologies in mobile and stationary applications. A relevant role of the fuel cell powered vehicles on the market of the transportation systems will be achieved only if the research and development of on-board vehicular hydrogen storage are able to allow a driving range of at least 500 km. The on-board hydrogen storage systems are more challenging due to the space, weight and cost limitations. This range of autonomy between refueling requires materials able to store at least 6.5% weight hydrogen, available at moderate pressures, at the working temperature of the fuel cells and with acceptable cycling stability. The intensive research on the hydrogen storage in alloys and intermetallic of the LaNi 5 , FeTi or Laves phase type compounds, which started more than three decades ago did not resulted in materials of more than about 3% H storage capacities. The 7.5% H content of the Mg hydride is still of attracting interest but though the absorption has been achieved at lower temperatures by ball milling magnesium with various amounts of nickel, the desorption can not be attained at 1 bar H 2 below 280 deg. C and the kinetics of the process is too slow. In the last decade, the attention is focused on another class of compounds, the complex hydrides of aluminum with alkali metals (alanates), due to their high hydrogen content. It was found that doping with Ti-based catalysts improve the hydrogenation/dehydrogenation conditions of NaAlH 4 . Later on, it was shown that ball milling with solid state catalysts greatly improve the hydrogen desorption kinetics of NaAlH 4 , and this also helps to the rehydriding process. The hydrogen desorption from NaAlH 4 occurs in three steps, it shows a reversible storage capacity of 5.5% H and this led to further research work for a better knowledge of its application relating properties. In this work, ball milling experiments on Na

  12. The growth of crystals of erbium hydride

    International Nuclear Information System (INIS)

    Grimshaw, J.A.; Spooner, F.J.; Wilson, C.G.; McQuillan, A.D.

    1981-01-01

    Crystals of the rare-earth hydride ErH 2 have been produced with face areas greater than a square millimetre and corresponding volumes exceeding those of earlier crystals by orders of magnitude. The hydride, which was produced in bulk polycrystalline form by hydriding erbium metal at 950 0 C, has been examined by optical and X-ray techniques. For material of composition ErH 2 and ErHsub(1.8) the size of the grains and their degree of strain appears to depend more on oxygen contamination during formation and on the subsequent cooling procedure, than on the size of erbium metal crystals in the starting material. (author)

  13. Ground rubber: Sorption media for ground water containing benzene and O-xylene

    International Nuclear Information System (INIS)

    Kershaw, D.S.; Pamukcu, S.

    1997-01-01

    The purpose of the current study is to examine the ability of ground rubber to sorb benzene and O-xylene from water contained with aromatic hydrocarbons. The study consisted of running both batch and packed bed column tests to determine the sorption capacity, the required sorption equilibration time, and the flow through utilization efficiency of ground rubber under various contact times when exposed to water contaminated with various amounts of benzene or O-xylene. Initial batch test results indicate that ground rubber can attain equilibrium sorption capacities up to 1.3 or 8.2 mg of benzene or O-xylene, respectively, per gram of tire rubber at solution equilibrium concentrations of 10 mg/L. Packed bed column tests indicate that ground tire rubber has on the average a 40% utilization rate when a hydraulic residence time of 15 min is used. Possible future uses of round rubber as a sorption media could include, but are not limited to, the use of ground rubber as an aggregate in slurry cutoff walls that are in contact with petroleum products. Ground rubber could also be used as a sorption media in pump-and-treat methodologies or as a sorption media in in-situ reactive permeable barriers

  14. Stress induced reorientation of vanadium hydride

    International Nuclear Information System (INIS)

    Beardsley, M.B.

    1977-10-01

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

  15. Uranium bed oxidation vacuum process system

    International Nuclear Information System (INIS)

    McLeland, H.L.

    1977-01-01

    Deuterium and tritium gases are occluded in uranium powder for release into neutron generator tubes. The uranium powder is contained in stainless steel bottles, termed ''beds.'' If these beds become damaged, the gases must be removed and the uranium oxidized in order not to be flammable before shipment to ERDA disposal grounds. This paper describes the system and methods designed for the controlled degassing and oxidation process. The system utilizes sputter-ion, cryo-sorption and bellows pumps for removing the gases from the heated source bed. Removing the tritium gas is complicated by the shielding effect of helium-3, a byproduct of tritium decay. This effect is minimized by incremental pressure changes, or ''batch'' processing. To prevent runaway exothermic reaction, oxidation of the uranium bed is also done incrementally, or by ''batch'' processing, rather than by continuous flow. The paper discusses in detail the helium-3 shielding effect, leak checks that must be made during processing, bed oxidation, degree of gas depletion, purity of gases sorbed from beds, radioactivity of beds, bed disposal and system renovation

  16. Hollow fiber adsorbents for CO2 capture: Kinetic sorption performance

    KAUST Repository

    Lively, Ryan P.

    2011-07-01

    We describe a CO 2 capture platform based on hollow polymeric fibers with sorbent particles embedded in the porous fiber wall for post-combustion CO 2 capture. These fibers are intended for use in a rapid temperature swing adsorption (RTSA) process. The RTSA system utilizes the hollow fiber morphology by flowing cooling water on the bore-side of the fibers during sorption to prevent temperature rise associated with the sorption enthalpy. Steam or hot water is flowed through the bores during desorption to desorb CO 2 rapidly. To minimize material transfer between the bore and the fiber wall, a dense Neoprene ® lumen layer is cast on the bore-side of the fiber wall. In this paper, the key sorption step and associated kinetic resistances for the uncooled fibers are examined and evaluated for this portion of the RTSA process. Chopped fibers in a packed bed, as well as fibers assembled into a parallel flow module, have been tested in a simulated flue gas stream. Kinetic limitations in the hollow fiber modules are largely overcome by increasing the superficial gas velocity and the fiber packing in the module-indicating that film diffusion is the controlling mass transfer limitation in the fiber system. The un-cooled fiber modules lose apparent capacity as superficial velocities are increased, likely indicating non-isothermal operation, whereas the actively-cooled fibers in the packed bed maintain apparent capacity at all flowrates studied. © 2011 Elsevier B.V.

  17. In situ hydride formation in titanium during focused ion milling.

    Science.gov (United States)

    Ding, Rengen; Jones, Ian P

    2011-01-01

    It is well known that titanium and its alloys are sensitive to electrolytes and thus hydrides are commonly observed in electropolished foils. In this study, focused ion beam (FIB) milling was used to prepare thin foils of titanium and its alloys for transmission electron microscopy. The results show the following: (i) titanium hydrides were observed in pure titanium, (ii) the preparation of a bulk sample in water or acid solution resulted in the formation of more hydrides and (iii) FIB milling aids the precipitation of hydrides, but there were never any hydrides in Ti64 and Ti5553.

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

    Energy Technology Data Exchange (ETDEWEB)

    Kubo, T., E-mail: kubo@nfd.co.jp [Nippon Nuclear Fuel Development Co., Ltd., 2163 Narita-cho, Oarai-machi, Ibaraki 311-1313 (Japan); Kobayashi, Y. [M.O.X. Co., Ltd., 1828-520 Hirasu-cho, Mito, Ibaraki 311-0853 (Japan)

    2013-08-15

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

  19. Sorption properties of carbon nanostructures

    International Nuclear Information System (INIS)

    Eletskii, Aleksandr V

    2004-01-01

    The current status of research in sorption properties of carbon nanotubes (CNTs) is reviewed. The structural peculiarities of CNTs, determining their sorption characteristics, are considered. The mechanisms of sorption of gaseous and condensed substances by such structures are analyzed. Special attention is paid to the problem of using CNTs for storing hydrogen and other gaseous substances. Methods for filling CNTs with liquid materials, based on capillary phenomena and wetting the graphite surface of the CNT with liquids of various nature, are considered. Properties of 'peapods' formed as a result of filling single-walled CNTs with fullerene molecules are reviewed. Also considered are perspectives on the applied usage of the sorption properties of CNTs in electrochemical and fuel cells, and material storage devices, as well as for producing superminiature metallic conductors. (reviews of topical problems)

  20. Removal of organic compounds from natural underground water in sorption and sono-sorption processes on selected activated carbons

    Directory of Open Access Journals (Sweden)

    Pietrzyk Andżelika

    2017-01-01

    Full Text Available The article rated removal efficiency of organic matter in the processes of sorption and sono-sorption of underground water grasped for municipal purposes. The studies were conducted in laboratory scale and verified in pilot scale at the Water Treatment Plant Tarnobrzeg-Jeziórko. In the research used granular activated carbons, ie. WD-Extra, WG-12, Norit Row 0.8 and Filtrasorb 300. The processes efficiency was evaluated on the basis of changes in the following parameters, ie.: total organic carbon (TOC, permanganate index, UV absorbance, turbidity and colour. The ultrasounds were generated by means of disintegrator Sonics&Materials VCX 130, using the sonication time of 1 and 5 minutes. The results obtained for the batch tests allowed to observe a beneficial effect of ultrasound on the efficiency of the removal of organic material in the sorption process. The combination of sonication and sorption on activated carbon increased the efficiency of the removal of organic matter by 6–37% for TOC, and 18.6–27.9% for permanganate index, depending on the sorbent used. The positive laboratory results were not confirmed in a pilot scale. In the flow conditions the sonication process did not affect the efficiency of removal of organic matter on the filter model with a bed of activated carbon.

  1. Characterisation of hydrides in a zirconium alloy, by EBSD

    International Nuclear Information System (INIS)

    Ubhi, H.S.; Larsen, K.

    2012-01-01

    Zirconium alloys are used in nuclear reactors owing to their low capture cross-section for thermal neutrons and good mechanical and corrosion properties. However, they do suffer from delayed hydrogen cracking (DHC) due to formation of hydride particles. This study shows how the electron back-scatter diffraction (EBSD) technique can be used to characterise hydrides and their orientation relationship with the matrix. Hydrided EB weld specimens were prepared by electro-polishing, characterised using Oxford instruments AZtecHKL EBSD apparatus and software attached to a FEG SEM. Hydrides were found to exist as fine intra granular plates and having the Blackburn orientation relationship, i.e. (0002)Zr//(111)hydride and (1120)Zr//(1-10)hydride. The hydrides were also found to contain sigma 3 boundaries as well as local misorientations. (author)

  2. Hydride formation on deformation twin in zirconium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ju-Seong [Korea Atomic Energy Research Institute, 989-111 Daedeokdaero, Yuseong-gu, Daejeon, 305-353 (Korea, Republic of); Kim, Sung-Dae [Korea Institute of Material Science (KIMS), 797 Changwondaero, Changwon, Gyeongnam, 642-831 (Korea, Republic of); Yoon, Jonghun, E-mail: yooncsmd@gmail.com [Department of Mechanical Engineering, Hanyang University, 1271 Sa3-dong, Sangrok-gu, Ansan-si, Gyeonggi-do, 426-791 (Korea, Republic of)

    2016-12-15

    Hydrides deteriorate the mechanical properties of zirconium (Zr) alloys used in nuclear reactors. Intergranular hydrides that form along grain boundaries have been extensively studied due to their detrimental effects on cracking. However, it has been little concerns on formation of Zr hydrides correlated with deformation twins which is distinctive heterogeneous nucleation site in hexagonal close-packed metals. In this paper, the heterogeneous precipitation of Zr hydrides at the twin boundaries was visualized using transmission electron microscopy. It demonstrates that intragranular hydrides in the twinned region precipitates on the rotated habit plane by the twinning and intergranular hydrides precipitate along the coherent low energy twin boundaries independent of the conventional habit planes. Interestingly, dislocations around the twin boundaries play a substantial role in the nucleation of Zr hydrides by reducing the misfit strain energy.

  3. A Study on the Radial Hydride Assisted Delayed Hydride Cracking of Zircaloy

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Jin-Ho; Lee, Ji-Min; Kim, Yong-Soo [Hanyang University, Seoul (Korea, Republic of)

    2015-05-15

    Extensive studies have been done on understanding of DHC(Delayed hydride cracking) phenomenon since several zirconium alloy pressure tubes failed in nuclear reactor in the 1970s. Recently, long-term dry storage strategy has been considered seriously in order to manage spent nuclear fuel in Korea and other countries around the world. Consequentially, many researches have been investigated the degradation mechanisms which will threaten the spent fuel integrity during dry storage and showed that hydrogen related phenomenon such as hydride reorientation and DHC are the critical factors. Especially, DHC is the direct cracking mechanism which can cause not only a through-wall defect but also a radiation leak to the environment. In addition, DHC can be enhanced by radial hydride as reported by Kim who demonstrate that radial hydrides clearly act as crack linkage path. This phenomenon is known as the radial hydride assisted DHC (RHA-DHC). Therefore, study on DHC is essential to ensure the safety of spent fuel. Finite element analysis will be carried out for the stress gradient evaluation around notch tip. A variation in thermal cycle which leads to change in hydrogen solid solution trajectory may be required. If the radial hydride precipitates at notch tip, we will investigate what conditions should be met. Ultimately, we will suggest the regulation criteria for long-term dry storage of spent nuclear fuel.

  4. Method for preparation of uranium hydride

    International Nuclear Information System (INIS)

    Gorski, M.S.; Goncalves, Miriam; Mirage, A.; Lima, W. de.

    1985-01-01

    A method for preparation of Uranium Hydride starting from Hidrogen and Uranium is described. In the temperature range of 250 0 up to 350 0 C, and pressures above 10torr, Hydrogen reacts smoothly with Uranium turnings forming a fine black or dark gray powder (UH 3 ). Samples containing a significant amount of oxides show a delay before the reaction begging. (Author) [pt

  5. Hydrogen isotope exchange in metal hydride columns

    International Nuclear Information System (INIS)

    Wiswall, R.; Reilly, J.; Bloch, F.; Wirsing, E.

    1977-01-01

    Several metal hydrides were shown to act as chromatographic media for hydrogen isotopes. The procedure was to equilibrate a column of hydride with flowing hydrogen, inject a small quantity of tritium tracer, and observe its elution behavior. Characteristic retention times were found. From these and the extent of widening of the tritium band, the heights equivalent to a theoretical plate could be calculated. Values of around 1 cm were obtained. The following are the metals whose hydrides were studied, together with the temperature ranges in which chromatographic behavior was observed: vanadium, 0 to 70 0 C; zirconium, 500 to 600 0 C; LaNi 5 , -78 to +30 0 C; Mg 2 Ni, 300 to 375 0 C; palladium, 0 to 70 0 C. A dual-temperature isotope separation process based on hydride chromatography was demonstrated. In this, a column was caused to cycle between two temperatures while being supplied with a constant stream of tritium-traced hydrogen. Each half-cycle was continued until ''breakthrough,'' i.e., until the tritium concentration in the effluent was the same as that in the feed. Up to that point, the effluent was enriched or depleted in tritium, by up to 20%

  6. Magnesium hydrides and their phase transitions

    Czech Academy of Sciences Publication Activity Database

    Paidar, Václav

    2016-01-01

    Roč. 41, č. 23 (2016), s. 9769-9773 ISSN 0360-3199 R&D Projects: GA MŠk(CZ) LD13069 Institutional support: RVO:68378271 Keywords : hydrogen * magnesium and transition metal hydrides * crystal structure stability * displacive phase transformations Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.582, year: 2016

  7. Are RENiAl hydrides metallic?

    Czech Academy of Sciences Publication Activity Database

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

    2009-01-01

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

  8. Lithium hydride hydrolysis: experimental and kinetic study

    International Nuclear Information System (INIS)

    Charton, S.; Maupoix, C.; Brevet, A.; Delaunay, F.; Heintz, O.; Saviot, L.

    2006-01-01

    In this work has been studied the contribution of various analyses techniques in the framework, on the one hand of revealing the mechanisms implied in lithium hydride hydrolysis, and on the other hand of studying the kinetics of hydrogen production. Among the methods recently investigated, Raman spectroscopy, XPS and SIMS seem to be particularly attractive. (O.M.)

  9. OPTIMIZATION OF INTERNAL HEAT EXCHANGERS FOR HYDROGEN STORAGE TANKS UTILIZING METAL HYDRIDES

    Energy Technology Data Exchange (ETDEWEB)

    Garrison, S.; Tamburello, D.; Hardy, B.; Anton, D.; Gorbounov, M.; Cognale, C.; van Hassel, B.; Mosher, D.

    2011-07-14

    Two detailed, unit-cell models, a transverse fin design and a longitudinal fin design, of a combined hydride bed and heat exchanger are developed in COMSOL{reg_sign} Multiphysics incorporating and accounting for heat transfer and reaction kinetic limitations. MatLab{reg_sign} scripts for autonomous model generation are developed and incorporated into (1) a grid-based and (2) a systematic optimization routine based on the Nelder-Mead downhill simplex method to determine the geometrical parameters that lead to the optimal structure for each fin design that maximizes the hydrogen stored within the hydride. The optimal designs for both the transverse and longitudinal fin designs point toward closely-spaced, small cooling fluid tubes. Under the hydrogen feed conditions studied (50 bar), a 25 times improvement or better in the hydrogen storage kinetics will be required to simultaneously meet the Department of Energy technical targets for gravimetric capacity and fill time. These models and methodology can be rapidly applied to other hydrogen storage materials, such as other metal hydrides or to cryoadsorbents, in future work.

  10. Reactor modeling of sorption-enhanced autothermal reforming of methane. Part I: Performance study of hydrotalcite and lithium zirconate-based processes

    NARCIS (Netherlands)

    Halabi, M.H.; Croon, de M.H.J.M.; Schaaf, van der J.; Cobden, P.D.; Schouten, J.C.

    2011-01-01

    This paper presents a performance analysis for the sorption-enhanced autothermal reforming of CH4 in a fixed bed reformer for pure H2 production with in situ CO2 capture. The process is analyzed for two candidate sorbents of K-promoted hydrotalcite and lithium zirconate in a fixed bed reactor using

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

    International Nuclear Information System (INIS)

    Silva, E.P. da.

    1981-01-01

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

  12. SYNTHESIS AND STRUCTURE OF BIS(PHENYLTETRAMETHYLCYCLOPENTADIENYL)TITANIUM(III) HYDRIDE - THE FIRST MONOMERIC BIS(CYCLOPENTADIENYL)TITANIUM(III) HYDRIDE : The First Monomeric Bis(cyclopentadienyl)titanium(III) Hydride

    NARCIS (Netherlands)

    de Wolf, J.M.; Meetsma, A.; Teuben, J.H

    1995-01-01

    The first structurally characterized monomeric bis(cyclopentadienyl)titanium(III) hydride, (C(5)PhMe(4))(2)TiH (4), was synthesized by hydrogenolysis of (C(5)PhMe(4))(2)TiMe (5). Hydride 4 was found to be a monomeric bent sandwich by X-ray diffraction methods, and the pentamethylcyclopentadienyl

  13. 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)

  14. The electrochemical impedance of metal hydride electrodes

    DEFF Research Database (Denmark)

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

    2002-01-01

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

  15. Metal hydrides based high energy density thermal battery

    International Nuclear Information System (INIS)

    Fang, Zhigang Zak; Zhou, Chengshang; Fan, Peng; Udell, Kent S.; Bowman, Robert C.; Vajo, John J.; Purewal, Justin J.; Kekelia, Bidzina

    2015-01-01

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

  16. Hydrides and Borohydrides of Light Elements

    Science.gov (United States)

    1947-12-04

    Troy, Attn: Inst. of Naval Science (30) Solar Aircraft Cu,, San Diego, Attn: Dr. M. A. Williamson " (31) INSMAT. N. J. for Itandard Oil Co., Esso Lab...with the other# iLD F.Re p. 8 ilt -ms" #61ggSotod that.. ir addition to thc impurity in the t~y..thr, an impurkty, prosumably aluminum hydride, in

  17. Facile Synthesis of Permethyl Yttrocene Hydride

    NARCIS (Netherlands)

    Haan, Klaas H. den; Teuben, Jan H.

    1984-01-01

    A convenient three step synthesis of (Cp*2YH)n (Cp* = C5Me5) is described starting with YCl3.3thf, in which Cp*2YCl.thf and Cp*2YCH(SiMe3)2 are intermediates, which could be isolated and characterized. The hydride is active in the activation of sp2 and sp3 C-H bonds as was demonstrated by the H-D

  18. Thermodynamic analysis of a thermally operated cascade sorption heat pump for continuous cold generation

    Energy Technology Data Exchange (ETDEWEB)

    Muthukumar, P.; Lakshmi, D.V.N. [Department of Mechanical Engineering, Indian Institute of Technology, Guwahati – 781039 (India)

    2013-07-01

    In this paper, the thermodynamic analysis of a cascade sorption system consists of a two-stage metal hydride heat pump as topping cycle and a single-stage lithium bromide water system as bottom cycle is presented. The effects of various operating temperatures such as driving heat, heat release and refrigeration temperatures, and design parameters such as ratio of metal hydride mass to reactor mass and sensible heat exchange factor on the combined coefficient of performance (COP) of the cascade cycle, and specific cooling power (SCP) and total cold output of the metal hydride heat pump cycle are presented. It is observed that the combined COP is found to increase with heat release and refrigeration temperatures and however, decreases with driving heat temperature. Increase of sensible heat exchange factor improves the system performances significantly. Reduction in mass ratio from 0.5 to 0.1 improves the combined COP of the cascade system by about 10 %. The maximum predicted combined COP of the system is about 1.66 at the driving heat, heat release and refrigeration temperatures of 270 deg C, 125 deg C and 12deg C, respectively.

  19. Evaluation of sorption distribution coefficient of Cs onto granite using sorption data collected in sorption database and sorption model

    International Nuclear Information System (INIS)

    Nagasaki, S.

    2013-01-01

    Based on the sorption distribution coefficients (K d ) of Cs onto granite collected from the JAERI Sorption Database (SDB), the parameters for a two-site model without the triple-layer structure were optimized. Comparing the experimentally measured K d values of Cs onto Mizunami granite carried out by JAEA with the K d values predicted by the model, the effect of the ionic strength on the K d values of Cs onto granite was evaluated. It was found that K d values could be determined using the content of biotite in granite at a sodium concentration ([Na]) of 1 x 10 -2 to 5 x 10 -1 mol/dm 3 . It was suggested that in high ionic strength solutions, the sorption of Cs onto other minerals such as microcline should also be taken into account. (author)

  20. Evaluation of sorption distribution coefficient of Cs onto granite using sorption data collected in sorption database and sorption model

    Energy Technology Data Exchange (ETDEWEB)

    Nagasaki, S., E-mail: nagasas@mcmaster.ca [McMaster Univ., Hamilton, Ontario (Canada)

    2013-07-01

    Based on the sorption distribution coefficients (K{sub d}) of Cs onto granite collected from the JAERI Sorption Database (SDB), the parameters for a two-site model without the triple-layer structure were optimized. Comparing the experimentally measured K{sub d} values of Cs onto Mizunami granite carried out by JAEA with the K{sub d} values predicted by the model, the effect of the ionic strength on the K{sub d} values of Cs onto granite was evaluated. It was found that K{sub d} values could be determined using the content of biotite in granite at a sodium concentration ([Na]) of 1 x 10{sup -2} to 5 x 10{sup -1} mol/dm{sup 3} . It was suggested that in high ionic strength solutions, the sorption of Cs onto other minerals such as microcline should also be taken into account. (author)

  1. HYDRIDE-RELATED DEGRADATION OF SNF CLADDING UNDER REPOSITORY CONDITIONS

    International Nuclear Information System (INIS)

    McCoy, K.

    2000-01-01

    The purpose and scope of this analysis/model report is to analyze the degradation of commercial spent nuclear fuel (CSNF) cladding under repository conditions by the hydride-related metallurgical processes, such as delayed hydride cracking (DHC), hydride reorientation and hydrogen embrittlement, thereby providing a better understanding of the degradation process and clarifying which aspects of the process are known and which need further evaluation and investigation. The intended use is as an input to a more general analysis of cladding degradation

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

    International Nuclear Information System (INIS)

    Rezchikov, V.G.; Skachkova, I.N.; Kuznetsova, T.S.; Khrushcheva, V.V.

    1985-01-01

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

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

    International Nuclear Information System (INIS)

    Garcia Gonzalez, F.

    1968-01-01

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

  4. Sorption isotherms, GAB parameters and isosteric heat of sorption

    NARCIS (Netherlands)

    Quirijns, E.J.; Boxtel, van A.J.B.; Loon, van W.K.P.; Straten, van G.

    2005-01-01

    The diffusion-sorption drying model has been developed as a physics-based way to model the decreasing drying rate at low moisture contents. This new model is founded on the existence of different classes of water: free and bound water. The transition between these classes and the corresponding

  5. Studies on sorption of plutonium on inorganic exchangers from sodium carbonate medium

    Energy Technology Data Exchange (ETDEWEB)

    Pius, I C; Charyulu, M M; Sivaramakrishnan, C K [Fuel Chemistry Division, Bhabha Atomic Research Centre, Mumbai (India); Venkataramani, B [Chemistry Division, Bhabha Atomic Research Centre, Mumbai (India)

    1994-06-01

    Sorption of Pu(IV) from sodium carbonate medium has been investigated by using different inorganic exchangers alumina, silica gel and hydrous titanium oxide. Distribution ratios of Pu(IV) for its sorption on these exchangers from sodium carbonate medium were found to be sufficiently high indicating the suitability of these exchangers for the removal of Pu(IV). The presence of uranium and dibutyl phosphate do not have any effect on distribution ratio. The 10% Pu(IV) breakthrough capacities for above exchangers have been determined with 5 ml bed at a flow rate of 30 ml/hour. (author). 4 refs., 2 tabs.

  6. Initiation of delayed hydride cracking in zirconium-2.5 wt% niobium

    International Nuclear Information System (INIS)

    Shalabi, A.F.; Meneley, D.A.

    1990-01-01

    Delayed hydride cracking in zirconium alloys is caused by the repeated precipitation and cracking of brittle hydrides. The growth kinetic of the hydrides have been measured to evaluate the critical hydride length for crack initiation. Hydride growth leading to crack initiation follows an approximate (time) 1/3 law on the average; crack propagation proceeds in a stepwise fashion. The critical length of hydride for crack initiation increases with stress and temperature. The fracture criterion for crack initiation predicts the critical hydride length at a give stress level and temperature. The fracture initiation mechanism of the hydride confirms the temperature effects for heating and cooling cycles under services loads. (orig.)

  7. Dynamic Simulation of a Periodic 10 K Sorption Cryocooler

    Science.gov (United States)

    Bhandari, P.; Rodriguez, J.; Bard, S.; Wade, L.

    1994-01-01

    A transient thermal simulation model has been developed to simulate the dynamic performance of a multiple-stage 10 K sorption cryocooler for spacecraft sensor cooling applications that require periodic quick-cooldown (under 2 minutes) , negligible vibration, low power consumption, and long life (5 to 10 years). The model was specifically designed to represent the Brilliant Eyes Ten-Kelvin Sorption Cryocooler Experiment (BETSCE), but it can be adapted to represent other sorption cryocooler systems as well. The model simulates the heat transfer, mass transfer, and thermodynamic processes in the cryostat and the sorbent beds for the entire refrigeration cycle, and includes the transient effects of variable hydrogen supply pressures due to expansion and overflow of hydrogen during the cooldown operation. The paper describes model limitations and simplifying assumptions, with estimates of errors induced by them, and presents comparisons of performance predictions with ground experiments. An important benefit of the model is its ability to predict performance sensitivities to variations of key design and operational parameters. The insights thus obtained are expected to lead to higher efficiencies and lower weights for future designs.

  8. Sorption on inactive repository components

    International Nuclear Information System (INIS)

    Gardiner, M.P.; Smith, A.J.; Williams, S.J.

    1990-11-01

    The near-field of an intermediate level/low level radioactive waste repository will contain significant quantities of iron and steel, Magnox and Zircaloy. Their corrosion products may possess significant sorption capacity for radioelements. The sorption of americium and plutonium onto magnesium hydroxide, zirconium hydroxide, colloidal magnetite and colloidal haematite has been studied under conditions typical of the porewater of a cementitious near-field. R D values ≥ 10 5 m g -1 were measured for both actinides on the oxides and hydroxides. These values are at least as great as those measured on crushed 3:1 Blast Furnace Slag/Ordinary Portland cement. Competitive sorption experiments have shown that sorption onto the corrosion products does not take place in preference to that on the cement or the converse. Magnetite and haematite colloids are positively charged in cement-equilibrated water whilst zirconium hydroxide is negatively charged. Crushed cement was found to be positively charged. Simple experiments show that only a small proportion of haematite colloids is potentially mobile through a column of crushed cement. (author)

  9. Sorption on inactive repository components

    International Nuclear Information System (INIS)

    Gardiner, M.P.; Smith, A.J.; Williams, S.J.

    1990-07-01

    The near-field of an intermediate level/low level radioactive waste repository will contain significant quantities of iron and steel, Magnox and Zircaloy. Their corrosion products may possess significant sorption capacity for radioelements. The sorption of americium and plutonium onto magnesium hydroxide, zirconium hydroxide, colloidal magnetite and colloidal haematite has been studied under conditions typical of the porewater of a cementitious near-field. R D values ≥ 10 5 ml g -1 were measured for both actinides on the oxides and hydroxides. These values are at least as great at those measured on crushed 3:1 Blast Furnace Slag/Ordinary Portland Cement. Competitive sorption experiments have shown that sorption onto the corrosion products does not take place in preference to that on the cement or the converse. Magnetite and haematite colloids are positively charged in cement-equilibrated water whilst zirconium hydroxide is negatively charged. Crushed cement was found to be positively charged. Simple experiments show that only a small proportion of haematite colloids is potentially mobile through a column of crushed cement. (author)

  10. Pyrophoric behaviour of uranium hydride and uranium powders

    Science.gov (United States)

    Le Guyadec, F.; Génin, X.; Bayle, J. P.; Dugne, O.; Duhart-Barone, A.; Ablitzer, C.

    2010-01-01

    Thermal stability and spontaneous ignition conditions of uranium hydride and uranium metal fine powders have been studied and observed in an original and dedicated experimental device placed inside a glove box under flowing pure argon. Pure uranium hydride powder with low amount of oxide (Oxidation mechanisms are proposed.

  11. Electrocatalytic hydride-forming compounds for rechageable batteries

    NARCIS (Netherlands)

    Notten, P.H.L.; Einerhand, R.E.F.

    1991-01-01

    Non-toxic intermetallic hydride-forming compounds are attractive alternatives to cadmium as the negative electrode materials in the new generation of Ni/metal hydride rechargeable batteries. High exchange currents and discharge efficiencies even at low temperatures can be achieved using highly

  12. Ultra-sonic observation in niobium hydride precipitation

    International Nuclear Information System (INIS)

    Florencio, O.; Pinatti, Dyonisio G.

    1982-01-01

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

  13. Creating nanoshell on the surface of titanium hydride bead

    Directory of Open Access Journals (Sweden)

    PAVLENKO Vyacheslav Ivanovich

    2016-12-01

    Full Text Available The article presents data on the modification of titanium hydride bead by creating titanium nanoshell on its surface by ion-plasma vacuum magnetron sputtering. To apply titanium nanoshell on the titanium hydride bead vacuum coating plant of multifunctional nanocomposite coatings QVADRA 500 located in the center of high technology was used. Analysis of the micrographs of the original surface of titanium hydride bead showed that the microstructure of the surface is flat, smooth, in addition the analysis of the microstructure of material surface showed the presence of small porosity, roughness, mainly cavities, as well as shallow longitudinal cracks. The presence of oxide film in titanium hydride prevents the free release of hydrogen and fills some micro-cracks on the surface. Differential thermal analysis of both samples was conducted to determine the thermal stability of the initial titanium hydride bead and bead with applied titanium nanoshell. Hydrogen thermal desorption spectra of the samples of the initial titanium hydride bead and bead with applied titanium nanoshell show different thermal stability of compared materials in the temperature range from 550 to 860о C. Titanium nanoshells applied in this way allows increasing the heat resistance of titanium hydride bead – the temperature of starting decomposition is 695о C and temperature when decomposition finishes is more than 1000о C. Modified in this way titanium hydride bead can be used as a filler in the radiation protective materials used in the construction or upgrading biological protection of nuclear power plants.

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

    International Nuclear Information System (INIS)

    Benamar, G.M.; Schweke, D.; Kimmel, G.; Mintz, M.H.

    2012-01-01

    Highlights: ► The preferred hydride growth orientations on gadolinium metal coated by a thin oxide layer are presented. ► A preferred growth of the (1 0 0) h plane of the face centered cubic (FCC) GdH 2 is observed for the hydride spots forming below the oxidation layer. ► A change to the (1 1 1) h plane of the cubic hydride dominates for the hydride's Growth Centers. ► The texture change is attributed to the surface normal compressive stress component exerted by the oxidation layer on the developing hydride. - Abstract: The initial development of hydrides on polycrystalline gadolinium (Gd), as on some other hydride forming metals, is characterized by two sequential steps. The first step involves the rapid formation of a dense pattern of small hydride spots (referred to as the “small family” of hydrides) below the native oxidation layer. The second stage takes place when some of the “small family” nucleants (referred to as “growth centers”, GCs) break the oxide layer, leading to their rapid growth and finally to the massive hydriding of the sample. In the present study, the texture of the two hydride families was studied, by combining X-ray diffraction (XRD) analysis with a microscopic analysis of the hydride, using scanning electron microscopy (SEM) and atomic force microscopy (AFM). It has been observed that for the “small family”, a preferred growth of the (1 0 0) h plane of the cubic GdH 2 takes place, whereas for the GCs, a change to the (1 1 1) h plane of the cubic hydride dominates. These preferred growth orientations were analyzed by their structure relation with the (0 0 .1) m basal plane of the Gd metal. It has been concluded that the above texture change is due to the surface normal compressive stress component exerted by the oxidation overlayer on the developing hydride, preventing the (0 0 .1) m ||(1 1 1) h growth orientation. This stress is relieved upon the rupture of that overlayer and the development of the GCs, leading to

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

    DEFF Research Database (Denmark)

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

    2006-01-01

    In this paper we have investigated the deposition, structure and decomposition of lithium and lithium-hydride films on a nickel substrate. Using surface sensitive techniques it was possible to quantify the deposited Li amount, and to optimize the deposition procedure for synthesizing lithium......-hydride films. By only making thin films of LiH it is possible to study the stability of these hydride layers and compare it directly with the stability of pure Li without having any transport phenomena or adsorbed oxygen to obscure the results. The desorption of metallic lithium takes place at a lower...... temperature than the decomposition of the lithium-hydride, confirming the high stability and sintering problems of lithium-hydride making the storage potential a challenge. (c) 2006 Elsevier B.V. All rights reserved....

  16. Minimizing hydride cracking in zirconium alloys

    International Nuclear Information System (INIS)

    Coleman, C.E.; Cheadle, B.A.; Ambler, J.F.R.; Eadie, R.L.

    1985-01-01

    Zirconium alloy components can fail by hydride cracking if they contain large flaws and are highly stressed. If cracking in such components is suspected, crack growth can be minimized by following two simple operating rules: components should be heated up from at least 30K below any operating temperature above 450K, and when the component requires cooling to room temperature from a high temperature, any tensile stress should be reduced as much and as quickly as is practical during cooling. This paper describes the physical basis for these rules

  17. Tritium immobilization and packaging using metal hydrides

    International Nuclear Information System (INIS)

    Holtslander, W.J.; Yaraskavitch, J.M.

    1981-04-01

    Tritium recovered from CANDU heavy water reactors will have to be packaged and stored in a safe manner. Tritium will be recovered in the elemental form, T 2 . Metal tritides are effective compounds in which to immobilize the tritium as a stable non-reactive solid with a high tritium capacity. The technology necessary to prepare hydrides of suitable metals, such as titanium and zirconium, have been developed and the properties of the prepared materials evaluated. Conceptual designs of packages for containing metal tritides suitable for transportation and long-term storage have been made and initial testing started. (author)

  18. Low-frequency excitations in zirconium hydrides

    International Nuclear Information System (INIS)

    Radulescu, A.; Padureanu, I.; Rapeanu, S.N.; Beldiman, A.; Kozlov, Zh.A.; Semenov, V.A.

    1999-01-01

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

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

    International Nuclear Information System (INIS)

    Rico, A.; Martin-Rengel, M.A.; Ruiz-Hervias, J.; Rodriguez, J.; Gomez-Sanchez, F.J.

    2014-01-01

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

  20. Application of acoustic emission to hydride cracking

    International Nuclear Information System (INIS)

    Sagat, S.; Ambler, J.F.R.; Coleman, C.E.

    1986-07-01

    Acoustic emission has been used for over a decade to study delayed hydride cracking (DHC) in zirconium alloys. At first acoustic emission was used primarily to detect the onset of DHC. This was possible because DHC was accompanied by very little plastic deformation of the material and furthermore the amplitudes of the acoustic pulses produced during cracking of the brittle hydride phase were much larger than those from dislocation motion and twinning. Acoustic emission was also used for measuring crack growth when it was found that for a suitable amplitude threshold, the total number of acoustic emission counts was linearly related to the cracked area. Once the proportionality constant was established, the acoustic counts could be converted to the crack length. Now the proportionality between the count rate and the crack growth rate is used to provide feedback between the crack length and the applied load, using computer technology. In such a system, the stress at the crack tip can be maintained constant during the test by adjusting the applied load as the crack progresses, or it can be changed in a predetermined manner, for example, to measure the threshold stress for cracking

  1. NATO Advanced Study Institute on Metal Hydrides

    CERN Document Server

    1981-01-01

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

  2. Waste form dissolution in bedded salt

    International Nuclear Information System (INIS)

    Kaufman, A.M.

    1980-01-01

    A model was devised for waste dissolution in bedded salt, a hydrologically tight medium. For a typical Spent UnReprocessed Fuel (SURF) emplacement, the dissolution rate wll be diffusion limited and will rise to a steady state value after t/sub eq/ approx. = 250 (1+(1-epsilon 0 ) K/sub D//epsilon 0 ) (years) epsilon 0 is the overpack porosity and K/sub d/ is the overpack sorption coefficient. The steady state dissolution rate itself is dominated by the solubility of UO 2 . Steady state rates between 5 x 10 -5 and .5 (g/year) are achievable by SURF emplacements in bedded salt without overpack, and rates between 5 x 10 -7 and 5 x 10 -3 (g/year) with an overpack having porosity of 10 -2

  3. Sorption Energy Maps of Clay Mineral Surfaces

    International Nuclear Information System (INIS)

    Cygan, Randall T.; Kirkpatrick, R. James

    1999-01-01

    A molecular-level understanding of mineral-water interactions is critical for the evaluation and prediction of the sorption properties of clay minerals that may be used in various chemical and radioactive waste disposal methods. Molecular models of metal sorption incorporate empirical energy force fields, based on molecular orbital calculations and spectroscopic data, that account for Coulombic, van der Waals attractive, and short-range repulsive energies. The summation of the non-bonded energy terms at equally-spaced grid points surrounding a mineral substrate provides a three dimensional potential energy grid. The energy map can be used to determine the optimal sorption sites of metal ions on the exposed surfaces of the mineral. By using this approach, we have evaluated the crystallographic and compositional control of metal sorption on the surfaces of kaolinite and illite. Estimates of the relative sorption energy and most stable sorption sites are derived based on a rigid ion approximation

  4. A study of stress reorientation of hydrides in zircaloy

    Energy Technology Data Exchange (ETDEWEB)

    Yourong, Jiang; Bangxin, Zhou [Nuclear Power Inst. of China, Chengdu, SC (China)

    1994-10-01

    Under the conditions of circumferential tensile stress from 70 to 180 MPa for Zircaloy tubes or the tensile stress from 55 to 180 MPa for Zircaloy-4 plates and temperature cycling between 150 and 400 degree C, the effects of stress and the number of temperature cycling on hydride reorientation in Zircaloy-4 tubes and plates and Zircaloy-2 tubes containing about 220 {mu}g/g hydrogen have been investigated. With the increase of stress and/or the number of temperature cycling, the level of hydride reorientation increases. When hydride reorientation takes place, there is a threshold stress concerned with the number of temperature cycling. Below the threshold stress, hydride reorientation is not obvious. When applied stress is higher than the threshold stress, the level of hydride reorientation increases with the increase of stress and the number of temperature cycling. Hydride reorientation in Zircaloy-4 tubes develops gradually from the outer surface to inner surface. It might be related to the difference of texture between outer surface and inner surface. The threshold stress is affected by both the texture and the value of B. So controlling texture could still restrict hydride reorientation under tensile stress.

  5. Applicability of microautoradiography to sorption studies

    International Nuclear Information System (INIS)

    Thompson, J.L.; Wolfsberg, K.

    1979-01-01

    The technique of microautoradiography was applied to the study of the sorption of uranium and americium on five rock types which exist at the Nevada Test Site. It was found that autoradiograms could be prepared in a few days which would allow the specific minerals responsible for sorption to be identified. Furthermore, the state of aggregation of the sorbed species was clearly indicated. It was concluded that microautoradiography was a useful adjunct to currently used methods for studying sorption of certain radionuclides

  6. Hydrogen storage in metal hydrides and complex hydrides; Wasserstoffspeicherung in Metall- und komplexen Hydriden - Schlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Bielmann, M.; Zuettel, A.

    2007-07-01

    This final report for the Swiss Federal Office of Energy (SFOE), reports on work done in 2007 at the Swiss Federal Laboratories for Materials Science and Technology EMPA on the storage of hydrogen in metal hydrides and complex hydrides. In particular, the use of tetrahydroborates is noted. The potential of this class of materials is stressed. The structures at room-temperature were examined using neutron and X-ray diffraction methods. Thermodynamic methods helped determine the thermodynamic stability of the materials. Also, a complete energy diagram for the materials was developed. The use of silicon oxide to reduce activation energy and its catalytic effects are discussed. The challenges placed by desorption mechanisms are noted. The authors note that reversibility is basically proven.

  7. Strontium sorption on Savannah River Plant soils

    International Nuclear Information System (INIS)

    Hoeffner, S.L.

    1984-12-01

    A laboratory study of strontium-85 sorption was conducted using Savannah River Plant soil and groundwater from the low-level waste burial ground. Systematic variation of soil and water composition indicates that strontium sorption is most strongly a function of pH. Changes in clay content and in K + , Ca 2+ , or Mg 2+ concentrations influence strontium sorption indirectly through the slight pH changes which result. The ions Na + , Cl - , and NO 3 - have no effect. Ferrous ion, added to groundwater to simulate the conditions of water at the bottom of waste trenches, did not account for low strontium sorption observed with some trench waters

  8. Complex metal hydrides for hydrogen, thermal and electrochemical energy storage

    DEFF Research Database (Denmark)

    Møller, Kasper T.; Sheppard, Drew; Ravnsbæk, Dorthe B.

    2017-01-01

    field. This review illustrates that complex metal hydrides may store hydrogen in the solid state, act as novel battery materials, both as electrolytes and electrode materials, or store solar heat in a more efficient manner as compared to traditional heat storage materials. Furthermore, it is highlighted...... how complex metal hydrides may act in an integrated setup with a fuel cell. This review focuses on the unique properties of light element complex metal hydrides mainly based on boron, nitrogen and aluminum, e.g., metal borohydrides and metal alanates. Our hope is that this review can provide new...

  9. Investigation process of alcoholysis of hydride aluminium-adobe

    International Nuclear Information System (INIS)

    Numanov, M.I.; Normatov, I.Sh.; Mirsaidov, U.M.

    2001-01-01

    Considering of that process of acid treatment of aluminium-adobe hydride realizes in the ethyl alcohol media it was necessary study the process of alcoholysis of AlH 3 and aluminium additives. In the end of article authors became to conclusion that deficiency of spontaneous alcoholysis of AlH 3 in adobe caused by protective action of fiber; solvate ability of LiCl and alkoxy aluminium hydride of lithium-LiCl·CO 2 H 5 OH, Li Al(OC 2 H 5 ) 4 ·nC 2 H 5 OH decreasing the expectancy of responding of alcohol with aluminium hydride

  10. Optimization and comprehensive characterization of metal hydride based hydrogen storage systems using in-situ Neutron Radiography

    Science.gov (United States)

    Börries, S.; Metz, O.; Pranzas, P. K.; Bellosta von Colbe, J. M.; Bücherl, T.; Dornheim, M.; Klassen, T.; Schreyer, A.

    2016-10-01

    For the storage of hydrogen, complex metal hydrides are considered as highly promising with respect to capacity, reversibility and safety. The optimization of corresponding storage tanks demands a precise and time-resolved investigation of the hydrogen distribution in scaled-up metal hydride beds. In this study it is shown that in situ fission Neutron Radiography provides unique insights into the spatial distribution of hydrogen even for scaled-up compacts and therewith enables a direct study of hydrogen storage tanks. A technique is introduced for the precise quantification of both time-resolved data and a priori material distribution, allowing inter alia for an optimization of compacts manufacturing process. For the first time, several macroscopic fields are combined which elucidates the great potential of Neutron Imaging for investigations of metal hydrides by going further than solely 'imaging' the system: A combination of in-situ Neutron Radiography, IR-Thermography and thermodynamic quantities can reveal the interdependency of different driving forces for a scaled-up sodium alanate pellet by means of a multi-correlation analysis. A decisive and time-resolved, complex influence of material packing density is derived. The results of this study enable a variety of new investigation possibilities that provide essential information on the optimization of future hydrogen storage tanks.

  11. Determination of hydrogen in zirconium hydride and uranium-zirconium hydride by inert gas exraction-gravimetric method

    International Nuclear Information System (INIS)

    Hoshino, Akira; Iso, Shuichi

    1976-01-01

    An inert gas extraction-gravimetric method has been applied to the determination of hydrogen in zirconium hydride and uranium-zirconium hydride which are used as neutron moderator and fuel of nuclear safety research reactor (NSRR), respectively. The sample in a graphite-enclosed quartz crucible is heated inductively to 1200 0 C for 20 min in a helium stream. Hydrogen liberated from the sample is oxidized to water by copper(I) oxide-copper(II) oxide at 400 0 C, and the water is determined gravimetrically by absorption in anhydrone. The extraction curves of hydrogen for zirconium hydride and uranium-zirconium hydride samples are shown in Figs. 2 and 3. Hydrogen in the samples is extracted quantitatively by heating at (1000 -- 1250) 0 C for (10 -- 40) min. Recoveries of hydrogen in the case of zirconium hydride were examined as follows: a weighed zirconium rod (5 phi x 6 mm, hydrogen -5 Torr. After the chamber was filled with purified hydrogen to 200 Torr, the rod was heated to 400 0 C for 15 h, and again weighed to determine the increase in weight. Hydrogen in the rod was then determined by the proposed method. The results are in excellent agreement with the increase in weight as shown in Table 1. Analytical results of hydrogen in zirconium hydride samples and an uranium-zirconium hydride sample are shown in Table 2. (auth.)

  12. Process for production of a metal hydride

    Science.gov (United States)

    Allen, Nathan Tait; Butterick, III, Robert; Chin, Arthur Achhing; Millar, Dean Michael; Molzahn, David Craig

    2014-08-12

    A process for production of a metal hydride compound MH.sub.x, wherein x is one or two and M is an alkali metal, Be or Mg. The process comprises combining a compound of formula (R.sup.1O).sub.xM with aluminum, hydrogen and at least one metal selected from among titanium, zirconium, hafnium, niobium, vanadium, tantalum and iron to produce a compound of formula MH.sub.x. R.sup.1 is phenyl or phenyl substituted by at least one alkyl or alkoxy group. A mole ratio of aluminum to (R.sup.1O).sub.xM is from 0.1:1 to 1:1. The catalyst is present at a level of at least 200 ppm based on weight of aluminum.

  13. Boron hydride analogues of the fullerenes

    International Nuclear Information System (INIS)

    Quong, A.A.; Pederson, M.R.; Broughton, J.Q.

    1994-01-01

    The BH moiety is isoelectronic with C. We have studied the stability of the (BH) 60 analogue of the C 60 fullerene as well as the dual-structure (BH) 32 icosahedron, both of them being putative structures, by performing local-density-functional electronic calculations. To aid in our analysis, we have also studied other homologues of these systems. We find that the latter, i.e., the dual structure, is the more stable although the former is as stable as one of the latter's lower homologues. Boron hydrides, it seems, naturally form the dual structures used in algorithmic optimization of complex fullerene systems. Fully relaxed geometries are reported as well as electron affinities and effective Hubbard U parameters. These systems form very stable anions and we conclude that a search for BH analogues of the C 60 alkali-metal supeconductors might prove very fruitful

  14. Hydrogen storage properties of metallic hydrides

    International Nuclear Information System (INIS)

    Latroche, M.; Percheron-Guegan, A.

    2005-01-01

    Nowadays, energy needs are mainly covered by fossil energies leading to pollutant emissions mostly responsible for global warming. Among the different possible solutions for greenhouse effect reduction, hydrogen has been proposed for energy transportation. Indeed, H 2 can be seen as a clean and efficient energy carrier. However, beside the difficulties related to hydrogen production, efficient high capacity storage means are still to be developed. Many metals and alloys are able to store large amounts of hydrogen. This latter solution is of interest in terms of safety, global yield and long term storage. However, to be suitable for applications, such compounds must present high capacity, good reversibility, fast reactivity and sustainability. In this paper, we will review the structural and thermodynamic properties of metallic hydrides. (authors)

  15. Artificial exomuscle investigations for applications-metal hydride

    International Nuclear Information System (INIS)

    Crevier, Marie-Charlotte; Richard, Martin; Rittenhouse, D Matheson; Roy, Pierre-Olivier; Bedard, Stephane

    2007-01-01

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

  16. 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.

  17. Electrochemical modeling of hydrogen storage in hydride-forming electrodes

    NARCIS (Netherlands)

    Ledovskikh, A.; Danilov, D.; Vermeulen, P.; Notten, P.H.L.

    2009-01-01

    An electrochemical kinetic model (EKM) is developed, describing the electrochemical hydrogen storage in hydride-forming materials under equilibrium conditions. This model is based on first principles of electrochemical reaction kinetics and statistical thermodynamics and describes the complex,

  18. Development of zirconium hydride highly effective moderator materials

    International Nuclear Information System (INIS)

    Yin Changgeng

    2005-10-01

    The zirconium hydride with highly content of hydrogen and low density is new efficient moderator material for space nuclear power reactor. Russia has researched it to use as new highly moderator and radiation protection materials. Japanese has located it between the top of pressure vessel and the main protection as a shelter, the work temperature is rach to 220 degree C. The zirconium hydride moderator blocks are main parts of space nuclear power reactor. Development of zirconium hydride moderator materials have strength research and apply value. Nuclear Power Research and Design Instituteoh China (NPIC) has sep up the hydrogenation device and inspect systems, and accumurate a large of experience about zirconium hydride, also set up a strict system of QA and QC. (authors)

  19. Precipitation of hydrides in high purity niobium after different treatments

    Energy Technology Data Exchange (ETDEWEB)

    Barkov, F.; Romanenko, A.; Trenikhina, Y.; Grassellino, A.

    2013-01-01

    Precipitation of lossy non-superconducting niobium hydrides represents a known problem for high purity niobium in superconducting applications. Using cryogenic optical and laser confocal scanning microscopy we have directly observed surface precipitation and evolution of niobium hydrides in samples after different treatments used for superconducting RF cavities for particle acceleration. Precipitation is shown to occur throughout the sample volume, and the growth of hydrides is well described by the fast diffusion-controlled process in which almost all hydrogen is precipitated at $T=140$~K within $\\sim30$~min. 120$^{\\circ}$C baking and mechanical deformation are found to affect hydride precipitation through their influence on the number of nucleation and trapping centers.

  20. Self-assembled air-stable magnesium hydride embedded in 3-D activated carbon for reversible hydrogen storage.

    Science.gov (United States)

    Shinde, S S; Kim, Dong-Hyung; Yu, Jin-Young; Lee, Jung-Ho

    2017-06-01

    The rational design of stable, inexpensive catalysts with excellent hydrogen dynamics and sorption characteristics under realistic environments for reversible hydrogen storage remains a great challenge. Here, we present a simple and scalable strategy to fabricate a monodispersed, air-stable, magnesium hydride embedded in three-dimensional activated carbon with periodic synchronization of transition metals (MHCH). The high surface area, homogeneous distribution of MgH 2 nanoparticles, excellent thermal stability, high energy density, steric confinement by carbon, and robust architecture of the catalyst resulted in a noticeable enhancement of the hydrogen storage performance. The resulting MHCH-5 exhibited outstanding hydrogen storage performance, better than that of most reported Mg-based hydrides, with a high storage density of 6.63 wt% H 2 , a rapid kinetics loading in hydrogenation compared to that of commercial MgH 2 . The origin of the intrinsic hydrogen thermodynamics was elucidated via solid state 1 H NMR. This work presents a readily scaled-up strategy towards the design of realistic catalysts with superior functionality and stability for applications in reversible hydrogen storage, lithium ion batteries, and fuel cells.

  1. Reactions of zinc hydride and magnesium hydride with pyridine; synthesis and characterization of 1,4-dihydro-1-pyridylzinc and -magnesium complexes

    NARCIS (Netherlands)

    Koning, A.J. de; Boersma, J.; Kerk, G.J.M. van der

    1980-01-01

    The synthesis and characterization of 1,4-dihydro-1-pyridylzinc and -magnesium complexes are described. Zinc hydride and magnesium hydride dissolve in and react with pyridine, and the reaction has been studied in detail in the case of zinc hydride. Evaporation of the solvent after 1–2 hours at 0°C

  2. Electronic structure of ternary hydrides based on light elements

    Energy Technology Data Exchange (ETDEWEB)

    Orgaz, E. [Departamento de Fisica y Quimica Teorica, Facultad de Quimica, Universidad Nacional Autonoma de Mexico, CP 04510 Coyoacan, Mexico, D.F. (Mexico)]. E-mail: orgaz@eros.pquim.unam.mx; Membrillo, A. [Departamento de Fisica y Quimica Teorica, Facultad de Quimica, Universidad Nacional Autonoma de Mexico, CP 04510 Coyoacan, Mexico, D.F. (Mexico); Castaneda, R. [Departamento de Fisica y Quimica Teorica, Facultad de Quimica, Universidad Nacional Autonoma de Mexico, CP 04510 Coyoacan, Mexico, D.F. (Mexico); Aburto, A. [Departamento de Fisica, Facultad de Ciencias, Universidad Nacional Autonoma de Mexico, CP 04510 Coyoacan, Mexico, D.F. (Mexico)

    2005-12-08

    Ternary hydrides based on light elements are interesting owing to the high available energy density. In this work we focused into the electronic structure of a series of known systems having the general formula AMH{sub 4}(A=Li,Na,M=B,Al). We computed the energy bands and the total and partial density of states using the linear-augmented plane waves method. In this report, we discuss the chemical bonding in this series of complex hydrides.

  3. Spectroscopy of helium hydride and triatomic hydrogen molecules

    International Nuclear Information System (INIS)

    Ketterle, W.

    1986-07-01

    Helium hydride and triatomic hydrogen has been produced by charge exchange between fast mass selected beams of molecular ions and alkali vapor. Using this method, the first discrete spectra of helium hydride were obtained. Fine electronic transitions with resolved rotational structure were observed in the visible and near infrared. Four isotopic mixtures were studied. Furthermore the first lifetime measurement of triatomic hydrogen states were performed and compared to theoretical predictions. (orig.)

  4. Proton location in metal hydrides using electron spin resonance

    International Nuclear Information System (INIS)

    Venturini, E.L.

    1979-01-01

    Electron spin resonance (ESR) of dilute paramagnetic ions establishes the site symmetry of these ions. In the case of metal hydrides the site symmetry is determined by the number and location of neighboring protons. Typical ESR spectra for trivalent erbium in scandium and yttrium hydrides are presented and analyzed, and this technique is shown to be a versatile microscopic probe of the location, net charge and occupation probability of nearby protons

  5. The Production of Uranium Metal by Metal Hydrides Incorporated

    Energy Technology Data Exchange (ETDEWEB)

    Alexander, P. P.

    1943-01-01

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

  6. Sorption of radionuclides on inorganic sorbents

    International Nuclear Information System (INIS)

    Rajec, P.; Matel, L.

    1995-01-01

    The sorption of cesium, strontium, plutonium and americium from water solution on natural zeolite, clay minerals, synthetic zeolites and ferrocyanides in silica gel matrix was studied. The same experiments but with synthetic zeolites irradiated by the dose 100 kGy proved no change in sorption properties. 1 tab., 4 refs

  7. Nitrate Sorption in an Agricultural Soil Profile

    Directory of Open Access Journals (Sweden)

    Wissem Hamdi

    2013-01-01

    Full Text Available Increasing concentrations of in surface water and groundwater can cause ecological and public health effects and has come under increased scrutiny by both environmental scientists and regulatory agencies. For many regions though, including the Sahel of Tunisia, little is known about the sorption capacity of soils. In this project we measured sorption by a profile of an iso-humic soil from Chott Meriem, Tunisia. Soil samples were collected from four soil depths (0–25, 25–60, 60–90, and 90–120 cm on 1 June 2011, and their sorption capacity was determined using batch experiments under laboratory conditions. The effects of contact time, the initial concentration, and the soil-solution ratio on sorption were investigated. In general, the results suggested that was weakly retained by the Chott Meriem soil profile. The quantity of sorption increased with depth, contact time, initial concentration, and soil-solution ratios. To evaluate the sorption capacities of the soil samples at concentrations ranging between 25 and 150 mg L−1 experimental data were fitted to both Freundlich and Langmuir isotherm sorption models. The results indicated that Freundlich model was better for describing sorption in this soil profile.

  8. AFFECTS OF MECHANICAL MILLING AND METAL OXIDE ADDITIVES ON SORPTION KINETICS OF 1:1 LiNH2/MgH2 MIXTURE

    Energy Technology Data Exchange (ETDEWEB)

    Erdy, C.; Anton, D.; Gray, J.

    2010-12-08

    The destabilized complex hydride system composed of LiNH{sub 2}:MgH{sub 2} (1:1 molar ratio) is one of the leading candidates of hydrogen storage with a reversible hydrogen storage capacity of 8.1 wt%. A low sorption enthalpy of {approx}32 kJ/mole H{sub 2} was first predicted by Alapati et al. utilizing first principle density function theory (DFT) calculations and has been subsequently confirmed empirically by Lu et al. through differential thermal analysis (DTA). This enthalpy suggests that favorable sorption kinetics should be obtainable at temperatures in the range of 160 C to 200 C. Preliminary experiments reported in the literature indicate that sorption kinetics are substantially lower than expected in this temperature range despite favorable thermodynamics. Systematic isothermal and isobaric sorption experiments were performed using a Sievert's apparatus to form a baseline data set by which to compare kinetic results over the pressure and temperature range anticipated for use of this material as a hydrogen storage media. Various material preparation methods and compositional modifications were performed in attempts to increase the kinetics while lowering the sorption temperatures. This paper outlines the results of these systematic tests and describes a number of beneficial additions which influence kinetics as well as NH{sub 3} formation.

  9. Affects of Mechanical Milling and Metal Oxide Additives on Sorption Kinetics of 1:1 LiNH2/MgH2 Mixture

    Directory of Open Access Journals (Sweden)

    Donald L. Anton

    2011-05-01

    Full Text Available The destabilized complex hydride system composed of LiNH2:MgH2 (1:1 molar ratio is one of the leading candidates of hydrogen storage with a reversible hydrogen storage capacity of 8.1 wt%. A low sorption enthalpy of ~32 kJ/mole H2 was first predicted by Alapati et al. utilizing first principle density function theory (DFT calculations and has been subsequently confirmed empirically by Lu et al. through differential thermal analysis (DTA. This enthalpy suggests that favorable sorption kinetics should be obtainable at temperatures in the range of 160 °C to 200 °C. Preliminary experiments reported in the literature indicate that sorption kinetics are substantially lower than expected in this temperature range despite favorable thermodynamics. Systematic isothermal and isobaric sorption experiments were performed using a Sievert’s apparatus to form a baseline data set by which to compare kinetic results over the pressure and temperature range anticipated for use of this material as a hydrogen storage media. Various material preparation methods and compositional modifications were performed in attempts to increase the kinetics while lowering the sorption temperatures. This paper outlines the results of these systematic tests and describes a number of beneficial additions which influence kinetics as well as NH3 formation.

  10. Radionuclide sorption and migration studies of getters for backfill barriers

    International Nuclear Information System (INIS)

    Nowak, E.J.

    1980-07-01

    Bentonite and hectorite clay minerals were chosen for study and development as potential backfill materials for testing in the proposed Waste Isolation Pilot Plant (WIPP), a radioactive waste repository and test facility in bedded salt. This choice of materials was based on initial screening results which are presented and on the predicted physical properties of these materials. These properties were verified experimentally in concentrated brines specific to the WIPP site. Distribution coefficients, K/sub d/, were calculated from batch sorption measurements on bentonite and hectorite in the nearly saturated brines A and B. The resulting K/sub d/ values were in the range of (1 to 5) x 10 3 ml/g for europium; (2 to 40) x 10 3 ml/g for plutonium(IV); and (4 to 16) x 10 3 ml/g for americium(III). A silica- and calcite-containing sand mixed with bentonite and hectorite acted as a sorber of americium(III) but was merely an inert diluent for plutonium(IV). Pertechnetate anions (TcO 4 - ) sorbed on activated charcoal with K/sub d/ values in the range of (0.2 to 0.4) x 10 3 ml/g. Pertechnetate, cesium, and strontium ions in brine were not sorbed appreciably by bentonite or hectorite. Although experimental evidence is given for a possible role of solubility in the sorption of europium on getters, other data presented here and evidence from the literature are inconsistent with a simple single reaction sorption mechanism. It is concluded that a backfill containing bentonite on hectorite and activated charcoal is potentially an effective barrier to the migration of Eu(III), Pu(IV), and Am(III) cations and, with further development, to the migration of TcO 4 - anions as well

  11. Electronic structure, bonding and chemisorption in metallic hydrides

    International Nuclear Information System (INIS)

    Ward, J.W.

    1980-01-01

    Problems that can arise during the cycling steps for a hydride storage system usually involve events at surfaces. Chemisorption and reaction processes can be affected by small amounts of contaminants that may act as catalytic poisons. The nature of the poisoning process can vary greatly for the different metals and alloys that form hydrides. A unifying concept is offered, which satisfactorily correlates many of the properties of transition-metal, rare-earth and actinide hydrides. The metallic hydrides can be differentiated on the basis of electronegativity, metallic radius (valence) and electronic structure. For those systems where there are d (transition metals) or f (early actinides) electrons near the Fermi level a broad range of chemical and catalytic behaviors are found, depending on bandwidth and energy. The more electropositive metals (rare-earths, actinides, transition metals with d > 5) dissolve hydrogen and form hydrides by an electronically somewhat different process, and as a class tend to adsorb electrophobic molecules. The net charge-transfer in either situation is subtle; however, the small differences are responsible for many of the observed structural, chemical, and catalytic properties in these hydride systems

  12. Mechanochemical synthesis of nanostructured chemical hydrides in hydrogen alloying mills

    International Nuclear Information System (INIS)

    Wronski, Z.; Varin, R.A.; Chiu, C.; Czujko, T.; Calka, A.

    2007-01-01

    Mechanical alloying of magnesium metal powders with hydrogen in specialized hydrogen ball mills can be used as a direct route for mechanochemical synthesis of emerging chemical hydrides and hydride mixtures for advanced solid-state hydrogen storage. In the 2Mg-Fe system, we have successfully synthesized the ternary complex hydride Mg 2 FeH 6 in a mixture with nanometric Fe particles. The mixture of complex magnesium-iron hydride and nano-iron released 3-4 wt.%H 2 in a thermally programmed desorption experiment at the range 285-295 o C. Milling of the Mg-2Al powder mixture revealed a strong competition between formation of the Al(Mg) solid solution and the β-MgH 2 hydride. The former decomposes upon longer milling as the Mg atoms react with hydrogen to form the hydride phase, and drive the Al out of the solid solution. The mixture of magnesium dihydride and nano-aluminum released 2.1 wt.%H 2 in the temperature range 329-340 o C in the differential scanning calorimetry experiment. The formation of MgH 2 was suppressed in the Mg-B system; instead, a hydrogenated amorphous phase (Mg,B)H x , was formed in a mixture with nanometric MgB 2 . Annealing of the hydrogen-stabilized amorphous mixture produced crystalline MgB 2

  13. The use of metal hydrides in fuel cell applications

    Directory of Open Access Journals (Sweden)

    Mykhaylo V. Lototskyy

    2017-02-01

    Full Text Available This paper reviews state-of-the-art developments in hydrogen energy systems which integrate fuel cells with metal hydride-based hydrogen storage. The 187 reference papers included in this review provide an overview of all major publications in the field, as well as recent work by several of the authors of the review. The review contains four parts. The first part gives an overview of the existing types of fuel cells and outlines the potential of using metal hydride stores as a source of hydrogen fuel. The second part of the review considers the suitability and optimisation of different metal hydrides based on their energy efficient thermal integration with fuel cells. The performances of metal hydrides are considered from the viewpoint of the reversible heat driven interaction of the metal hydrides with gaseous H2. Efficiencies of hydrogen and heat exchange in hydrogen stores to control H2 charge/discharge flow rates are the focus of the third section of the review and are considered together with metal hydride – fuel cell system integration issues and the corresponding engineering solutions. Finally, the last section of the review describes specific hydrogen-fuelled systems presented in the available reference data.

  14. Metal hydrides based high energy density thermal battery

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-10-05

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

  15. Sorption of mercury on chemically synthesized polyaniline

    International Nuclear Information System (INIS)

    Remya Devi, P.S.; Verma, R.; Sudersanan, M.

    2006-01-01

    Sorption of inorganic mercury (Hg 2+ ) and methyl mercury, on chemically synthesized polyaniline, in 0.1-10N HCl solutions has been studied. Hg 2+ is strongly sorbed at low acidities and the extent of sorption decreases with increase in acidity. The sorption of methyl mercury is very low in the HCl concentration range studied. Sorption of Hg 2+ on polyaniline in 0.1-10N LiCl and H 2 SO 4 solutions has also been studied. The analysis of the data indicates that the sorption of Hg 2+ depends on the degree of protonation of polyaniline and the nature of mercury(II) chloride complexes in solution. X-ray photoelectron spectroscopy analysis (XPS) of polyaniline sorbed with mercury show that mercury is bound as Hg 2+ . Sorbed mercury is quantitatively eluted from polyaniline with 0.5N HNO 3 . Polyaniline can be used for separation and pre-concentration of inorganic mercury from aqueous samples. (author)

  16. Phenanthrene sorption on biochar-amended soils

    DEFF Research Database (Denmark)

    Kahawaththa Gamage, Inoka Damayanthi Kumari; Moldrup, Per; Paradelo Pérez, Marcos

    2014-01-01

    on their influences on the sorption of environmental contaminants. In a field-based study at two experimental sites in Denmark, we investigated the effect of birch wood-derived biochar (Skogans kol) on the sorption of phenanthrene in soils with different properties. The soil sorption coefficient, Kd (L kg-1......), of phenanthrene was measured on sandy loam and loamy sand soils which have received from zero up to 100 t ha-1 of biochar. Results show that birch wood biochar had a higher Kd compared to soils. Furthermore, the application of birch wood biochar enhanced the sorption of phenanthrene in agricultural soils...... carbon, while it negatively correlated with clay content. The results also revealed that biochar-mineral interactions play an important role in the sorption of phenanthrene in biochar-amended soil....

  17. Cobalt sorption onto Savannah River Plant soils

    International Nuclear Information System (INIS)

    Hoeffner, S.L.

    1985-06-01

    A laboratory study of cobalt-60 sorption was conducted using Savannah River Plant soil and groundwater from the low-level waste burial ground. Systematic variation of soil and water composition indicates that cobalt sorption is most strongly a function of pH. Over a pH range of 2 to 9, the distribution coefficient ranged from 2 to more than 10,000 mL/g. Changes in clay content and in K + , Ca 2+ , or Mg 2+ concentrations influence cobalt sorption indirectly through the slight pH changes which result. The ions Na + , Cl - , and NO 3 - have no effect on cobalt sorption. Ferrous ion, added to groundwater to simulate the condition of water at the bottom of the waste trenches, accounts for part of the decrease in cobalt sorption observed with trench waters. 17 refs., 3 figs., 4 tabs

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

    International Nuclear Information System (INIS)

    Balart, Silvia N.; Bruzzoni, Pablo; Granovsky, Marta S.; Gribaudo, Luis M. J.; Hermida, Jorge D.; Ovejero, Jose; Rubiolo, Gerardo H.; Vicente, Eduardo E.

    2000-01-01

    Uranium-molybdenum alloys are been tested as a component in high-density LEU dispersion fuels with very good performances. These alloys need to be transformed to powder due to the manufacturing requirements of the fuels. One method to convert ductile alloys into powder is the hydride-de hydride process, which takes advantage of the ability of the U-α phase to transform to UH 3 : a brittle and relatively low-density compound. U-Mo alloys around 7 and 8 wt % Mo were melted and heat treated at different temperature ranges in order to partially convert γ -phase to α -phase. Subsequent hydriding transforms this α -phase to UH 3 . The volume change associated to the hydride formation embrittled the material which ends up in a powdered alloy. Results of the optical metallography, scanning electron microscopy, X-ray diffraction during different steps of the process are shown. (author)

  19. Reversible Ammonia Sorption for the Primary Life Support System (PLSS)

    Science.gov (United States)

    Wojtowicz, Marek A.; Cosgrove, Joseph E.; Serio, Michael A.; Jennings, Mallory A.

    2012-01-01

    Results are presented on the development of regenerable trace-contaminant (TC) sorbent for use in Extravehicular Activities (EVAs), and more specifically in the Primary Life Support System (PLSS). Since ammonia is the most important TC to be captured, data presented in this paper are limited to ammonia sorption, with results relevant to other TCs to be reported at a later time. The currently available TC-control technology involves the use of a packed bed of acid-impregnated granular charcoal. The sorbent is non-regenerable, and its use is associated with appreciable pressure drop, i.e. power consumption. The objective of this work is to demonstrate the feasibility of using vacuum-regenerable sorbents for PLSS application. In this study, several carbon sorbent monoliths were fabricated and tested. Multiple adsorption/vacuum-regeneration cycles were demonstrated at room temperature, as well as carbon surface conditioning that enhances ammonia sorption without impairing sorbent regeneration. Depending on sorbent monolith geometry, the reduction in pressure drop with respect to granular sorbent was found to be between 50% and two orders of magnitude. Resistive heating of the carbon sorbent monolith was demonstrated by applying voltage to the opposite ends of the monolith.

  20. Practice Hospital Bed Safety

    Science.gov (United States)

    ... Home For Consumers Consumer Updates Practice Hospital Bed Safety Share Tweet Linkedin Pin it More sharing options ... It depends on the complexity of the bed." Safety Tips CDRH offers the following safety tips for ...

  1. Bed Bugs and Schools

    Science.gov (United States)

    Bed bugs have long been a pest – feeding on blood, causing itchy bites and generally irritating their human hosts. They are successful hitchhikers, and can move from an infested site to furniture, bedding, baggage, boxes, and clothing.

  2. Effect of electronegativity on the mechanical properties of metal hydrides with a fluorite structure

    International Nuclear Information System (INIS)

    Ito, Masato; Setoyama, Daigo; Matsunaga, Junji; Muta, Hiroaki; Kurosaki, Ken; Uno, Masayoshi; Yamanaka, Shinsuke

    2006-01-01

    Bulk titanium, yttrium, and zirconium hydrides, which have the same structure as that of fluorite-type fcc C 1, were produced and their mechanical properties were investigated. With an increase in the hydrogen content, the lattice parameters of titanium and zirconium hydrides increased, whereas those of yttrium hydride decreased. The elastic moduli of titanium and zirconium hydrides decreased by hydrogen addition, whereas those of yttrium hydride increased. There are linear relations between the electronegativities and hydrogen content dependence of the properties. Therefore, the mechanical properties of the metal hydrides are considered to be determined by a common rule based on the electronegativity

  3. Fullerene hydride - A potential hydrogen storage material

    International Nuclear Information System (INIS)

    Nai Xing Wang; Jun Ping Zhang; An Guang Yu; Yun Xu Yang; Wu Wei Wang; Rui long Sheng; Jia Zhao

    2005-01-01

    Hydrogen, as a clean, convenient, versatile fuel source, is considered to be an ideal energy carrier in the foreseeable future. Hydrogen storage must be solved in using of hydrogen energy. To date, much effort has been put into storage of hydrogen including physical storage via compression or liquefaction, chemical storage in hydrogen carriers, metal hydrides and gas-on-solid adsorption. But no one satisfies all of the efficiency, size, weight, cost and safety requirements for transportation or utility use. C 60 H 36 , firstly synthesized by the method of the Birch reduction, was loaded with 4.8 wt% hydrogen indicating [60]fullerene might be as a potential hydrogen storage material. If a 100% conversion of C 60 H 36 is achieved, 18 moles of H 2 gas would be liberated from each mole of fullerene hydride. Pure C 60 H 36 is very stable below 500 C under nitrogen atmosphere and it releases hydrogen accompanying by other hydrocarbons under high temperature. But C 60 H 36 can be decomposed to generate H 2 under effective catalyst. We have reported that hydrogen can be produced catalytically from C 60 H 36 by Vasks's compound (IrCl(CO)(PPh 3 ) 2 ) under mild conditions. (RhCl(CO)(PPh 3 ) 2 ) having similar structure to (IrCl(CO)(PPh 3 ) 2 ), was also examined for thermal dehydrogenation of C 60 H 36 ; but it showed low catalytic activity. To search better catalyst, palladium carbon (Pd/C) and platinum carbon (Pt/C) catalysts, which were known for catalytic hydrogenation of aromatic compounds, were tried and good results were obtained. A very big peak of hydrogen appeared at δ=5.2 ppm in 1 H NMR spectrum based on Evans'work (fig 1) at 100 C over a Pd/C catalyst for 16 hours. It is shown that hydrogen can be produced from C 60 H 36 using a catalytic amount of Pd/C. Comparing with Pd/C, Pt/C catalyst showed lower activity. The high cost and limited availability of Vaska's compounds, Pd and Pt make it advantageous to develop less expensive catalysts for our process based on

  4. Manganese Silylene Hydride Complexes: Synthesis and Reactivity with Ethylene to Afford Silene Hydride Complexes.

    Science.gov (United States)

    Price, Jeffrey S; Emslie, David J H; Britten, James F

    2017-05-22

    Reaction of the ethylene hydride complex trans-[(dmpe) 2 MnH(C 2 H 4 )] (1) with Et 2 SiH 2 at 20 °C afforded the silylene hydride [(dmpe) 2 MnH(=SiEt 2 )] (2 a) as the trans-isomer. By contrast, reaction of 1 with Ph 2 SiH 2 at 60 °C afforded [(dmpe) 2 MnH(=SiPh 2 )] (2 b) as a mixture of the cis (major) and trans (minor) isomers, featuring a Mn-H-Si interaction in the former. The reaction to form 2 b also yielded [(dmpe) 2 MnH 2 (SiHPh 2 )] (3 b); [(dmpe) 2 MnH 2 (SiHR 2 )] (R=Et (3 a) and Ph (3 b)) were accessed cleanly by reaction of 2 a and 2 b with H 2 , and the analogous reactions with D 2 afforded [(dmpe) 2 MnD 2 (SiHR 2 )] exclusively. Both 2 a and 2 b engaged in unique reactivity with ethylene, generating the silene hydride complexes cis-[(dmpe) 2 MnH(R 2 Si=CHMe)] (R=Et (4 a), Ph (4 b)). Compounds trans-2 a, cis-2 b, 3 b, and 4 b were crystallographically characterized, and bonding in 2 a, 2 b, 4 a, and 4 b was probed computationally. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Prediction of metal sorption in soils

    International Nuclear Information System (INIS)

    Westrich, Henry R.; Anderson, Harold L. Jr.; Arthur, Sara E.; Brady, Patrick V.; Cygan, Randall T.; Liang, Jianjie; Zhang, Pengchu; Yee, N.

    2000-01-01

    Radionuclide transport in soils and groundwaters is routinely calculated in performance assessment (PA) codes using simplified conceptual models for radionuclide sorption, such as the K D approach for linear and reversible sorption. Model inaccuracies are typically addressed by adding layers of conservativeness (e.g., very low K D 's), and often result in failed transport predictions or substantial increases in site cleanup costs. Realistic assessments of radionuclide transport over a wide range of environmental conditions can proceed only from accurate, mechanistic models of the sorption process. They have focused on the sorption mechanisms and partition coefficients for Cs + , Sr 2+ and Ba 2+ (analogue for Ra 2+ ) onto iron oxides and clay minerals using an integrated approach that includes computer simulations, sorption/desorption measurements, and synchrotron analyses of metal sorbed substrates under geochemically realistic conditions. Sorption of Ba 2+ and Sr 2+ onto smectite is strong, pH-independent, and fully reversible, suggesting that cation exchange at the interlayer basal sites controls the sorption process. Sr 2+ sorbs weakly onto geothite and quartz, and is pH-dependent. Sr 2+ sorption onto a mixture of smectite and goethite, however, is pH- and concentration dependent. The adsorption capacity of montmorillonite is higher than that of goethite, which may be attributed to the high specific surface area and reaction site density of clays. The presence of goethite also appears to control the extent of metal desorption. In-situ, extended X-ray absorption fine structure (EXAFS) spectroscopic measurements for montmorillonite and goethite show that the first shell of adsorbed Ba 2+ is coordinated by 6 oxygens. The second adsorption shell, however, varies with the mineral surface coverage of adsorbed Ba 2+ and the mineral substrate. This suggests that Ba 2+ adsorption on mineral surfaces involves more than one mechanism and that the stability of sorbed

  6. Sorption of cesium and strontium from concentrated brines by backfill barrier materials

    International Nuclear Information System (INIS)

    Winslow, C.D.

    1981-03-01

    The sorption of radionuclides from potentially intruding groundwater at a nuclear waste repository is a major chemical function of backfill barriers. In this study, various materials (including clays, zeolites and an inorganic ion exchanger) were screened for the sorption of the fission products cesium and strontium in concentrated brines. Representative brines A and B for the Waste Isolation Pilot Plant (WIPP), a proposed radioactive waste repository and test facility in bedded salt were used. Sorption properties were quantified using empirical distribution coefficients, k/sub d/. Of the materials examined, sodium titanate had the highest k/sub d/ for the sorption of Sr(II) in both brine A (k/sub d/ = 125 ml/g) and brine B(k/sub d/ = 500 to 600 ml/g). A mordenite-type zeolite was the most effective getter for Cs(I) in brine A (k/sub d = 27 ml/g), while illite yielded the highest k/sub d/ for Cs(I) in brine B (k/sub d/ = 115 ml/g). The relative merit of these k/sub d/ values is evaluated in terms of calculated estimates of breakthrough times for a backfill barrier containing the getter. Results show that a backfill mixture containing these getters is potentially an effective barrier to the migration of Sr(II) and Cs(I), although further study (especially for the sorption of cesium from brine A) is recommended. Initial mechanistic studies revealed competing ion effects which would support an ion exchange mechanism. K/sub d/'s were constant over a Sr(II) concentration range of 10 -11 to 10 -5 M and a Cs(I) concentration range of 10 -8 to 10 -5 M, supporting the choice of a linear sorption isotherm as a model for the results. Constant batch composition was shown to be attained within one week

  7. Chemical Hydride Slurry for Hydrogen Production and Storage

    Energy Technology Data Exchange (ETDEWEB)

    McClaine, Andrew W

    2008-09-30

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

  8. Sorption behavior of cesium onto bentonite colloid

    International Nuclear Information System (INIS)

    Iijima, Kazuki; Masuda, Tsuguya; Tomura, Tsutomu

    2004-01-01

    It is considered that bentonite colloid might be generated from bentonite which will be used as buffer material in geological disposal system, and can facilitate the migration of radionuclides by means of sorption. In order to examine this characteristic, sorption and desorption experiments of Cs onto bentonite colloid were carried out to obtain its distribution coefficient (Kd) and information on the reversibility of its sorption. In addition, particle size distribution and shape of colloid were investigated and their effect on the sorption behavior was discussed. Kds for Cs were around 20 m 3 /kg for sorption and 30 m 3 /kg for desorption, in which sorbed Cs was desorbed by 8.4x10 -4 mol/l of NaCl solution. These values did not show any dependencies on Cs concentration and duration of sorption and desorption. The first 20% of sorbed Cs was desorbed reversibly at least. Most of colloidal particles were larger than 200 nm and TEM micrographs showed they had only several sheets of the clay crystal. Obtained Kds for colloidal bentonite were larger than those for powdered bentonite. This can be caused by difference of competing ions in the solution, characteristics of contained smectite, or sorption site density. (author)

  9. Sorption of uranyl ions on hydrous oxides

    International Nuclear Information System (INIS)

    Gupta, A.R.; Venkataramani, B.

    1988-01-01

    Sorption of uranyl ions on hydrous titanium oxide (HTiO), magnetite (MAG), and hydrous thorium oxide (HThO) has been studied as a function of pH. Hydrous oxides have been characterized by their pH-titration curves, intrinsic dissociation constants (pK ai * ) and point of zero charge (pH pzc ). The fraction of protonated surface hydroxyl groups as well as the surface pH (pH surf ) as a function of solution pH have been computed. The distribution of various hydrolyzed species of uranyl ions with solution pH have been compared with uranyl sorption isotherm on these oxides. Sorption edge in all the cases occurs when free hydroxyl groups are available on the surface and pH surf is sufficiently high to favor the formation of dimer-like species on the surface. A new model for the sorption process, called surface hydrolysis model, which explains these and other features of uranyl sorption on hydrous oxides has been proposed. The model visualizes the sorption process as linking of uranyl ions with two adjacent free surface hydroxyl groups without deprotonation (provided the surface pH is high for the hydrolysis of uranyl ions) and formation of dimer-like structures on the surface. The new model has been successfully applied to the present and other available data on uranyl ion sorption on hydrous oxides. (author)

  10. Sorption equilibria of ethanol on cork.

    Science.gov (United States)

    Lequin, Sonia; Chassagne, David; Karbowiak, Thomas; Bellat, Jean-Pierre

    2013-06-05

    We report here for the first time a thermodynamic study of gaseous ethanol sorption on raw cork powder and plate. Our study aims at a better understanding of the reactivity of this material when used as a stopper under enological conditions, thus in close contact with a hydroethanolic solution, wine. Sorption−desorption isotherms were accurately measured by thermogravimetry at 298 K in a large range of relative pressures. Sorption enthalpies were determined by calorimetry as a function of loading. Sorption−desorption isotherms exhibit a hysteresis loop probably due to the swelling of the material and the absorption of ethanol. Surprisingly, the sorption enthalpy of ethanol becomes lower than the liquefaction enthalpy as the filling increases. This result could be attributed to the swelling of the material, which would generate endothermic effects. Sorption of SO₂ on cork containing ethanol was also studied. When the ethanol content in cork is 2 wt %, the amount of SO₂ sorbed is divided by 2. Thus, ethanol does not enhance the sorption rate for SO₂ but, on the contrary, decreases the SO₂ sorption activity onto cork, probably because of competitive sorption mechanisms.

  11. Sorption of streptococcus faecium to glass

    International Nuclear Information System (INIS)

    Oerstavik, D.

    1977-01-01

    A method has been developed by which to study the sorption of Streptococcus faecium to soda-lime cover glasses. Conditions were chosen to minimize the influence on sorption of bacterial polymer production, passive sorption being studied rather than attachment mediated by metabolic activities. Sorption of S. faecium increased with increasing temperature (to 50degC), time, and cell concentration, but equilibrium apparently was not reached even after incubation for 8 hours or at a cell concentration of 3 x 10 10 per ml. Sorption increased with solute molarity up to 0.1 M concentration of NaCl and KCl, indicating an effect of the electrical double layers on the apposition of cells to the glass surface. Desorption of bacteria could be obtained after multiple washings of the glasses in buffer or by the action of Tween 80, but not if sorbed bacteria were left in distilled water, various salt solutions, urea, or in suspensions of unlabelled bacteria. It was concluded that sorption occurred as a result of chemical interactions between the glass and the cell surface. Tween 80 at a concentration of 1 per cent inhibited sorption to 26 per cent of buffer controls, 2 M urea was less effective, and 1 M NaCl was without effect. It is suggested that hydrophobic interactions may be of importance in the binding of S. faecium to glass. (author)

  12. Solubility of hydrogen isotopes in stressed hydride-forming metals

    International Nuclear Information System (INIS)

    Coleman, C.E.; Ambler, J.F.R.

    1983-01-01

    Components made from hydride-forming metals can be brittle when particles of hydride are present. The solid solubility limit of hydrogen in these metals needs to be known so that fracture resistance can be properly assessed. Stress affects the solubility of hydrogen in metals. As hydrogen dissolves the metal volume increases, an applied hydrostatic tensile stress supplies work to increase the solubility. Precipitation of hydrides increases the volume further. A hydrostatic tensile stress promotes the formation of hydrides and tends to reduce the terminal solubility. For materials containing hydrogen in solution in equilibrium with hydrides, the effect of stress on the terminal solubility is given. Hydrogen migrates up tensile stress gradients because of the effect of stress on the solubility and solubility limit. Consequently, hydrogen concentrates at flaws. When hydrides are present in the metal matrix, those remote from the flaw tip will preferentially dissolve in favor of those precipitated at the flaw. If the stress is large enough, at some critical condition the hydrides at the flaw will crack. This is delayed hydrogen cracking. Notched and fatigue-cracked cantilever beam specimens (6) (38 x 4 x 3 mm) were machined from the circumferential direction of several cold-worked Zr-2.5 at. % Nb pressure tubes. The chemical compositions had the ranges (in atomic %) Nb - 2.5 to 2.7; O - 0.58 to 0.71; H - 0.018 to 0.18. The effect of test temperature is for a specimen containing 0.13 at. % protium and 0.29 at .% deuterium. Between 505 K and 530 K was less than 1 hr, between 530 K and 537 K it increased to 25.8 h, while at 538 K no cracking was observed up to the 54 h

  13. Influence of uranium hydride oxidation on uranium metal behaviour

    International Nuclear Information System (INIS)

    Patel, N.; Hambley, D.; Clarke, S.A.; Simpson, K.

    2013-01-01

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

  14. Influence of uranium hydride oxidation on uranium metal behaviour

    Energy Technology Data Exchange (ETDEWEB)

    Patel, N.; Hambley, D. [National Nuclear Laboratory (United Kingdom); Clarke, S.A. [Sellafield Ltd (United Kingdom); Simpson, K.

    2013-07-01

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

  15. Developments in delayed hydride cracking in zirconium alloys

    International Nuclear Information System (INIS)

    Puls, Manfred P.

    2008-01-01

    Delayed hydride cracking (DHC) is a process of diffusion assisted localized hydride embrittlement at flaws or regions of high stress. Models of DHC propagation and initiation have been developed that capture the essential elements of this phenomenon in terms of parameters describing processes occurring at the micro-scale. The models and their predictions of experimental results applied to Zr alloys are assessed. The propagation model allows rationalization of the effect of direction of approach to temperature and of the effect of the state and morphology of the beta phase in Zr-2.5Nb on DHC velocity. The K I dependence of the DHC velocity can only be approximately rationalized by the propagation models. This is thought to be because these models approximate the DHC velocity by a constant and shape-invariant rate of growth of the hydride at the flaw and have not incorporated a coupling between the applied stress field due to the flaw alone and the precipitated hydrides that would result in a variation of the shape and density of the hydrided region with K I . Separately, models have been developed for DHC initiation at cracks and blunt flaws. Expressions are obtained for the threshold stress intensity factor, K IH , for DHC initiation at a crack. A model for K IH has been used to rationalize the experimental result that DHC initiation is not possible above a certain temperature, even when hydrides can form at the crack tip. For blunt flaws with root radii in the μm range, and engineering process zone procedure has been derived to determine the initiation conditions requiring that both a critical stress and a critical flaw tip displacement must be achieved for hydride fracture. The engineering process zone procedure takes account of the dependence of DHC initiation on the flaw's root radius. Although all of the foregoing models are capable of describing the essential features of DHC, they are highly idealized and in need of further refinement. (author)

  16. Multidimensional simulations of hydrides during fuel rod lifecycle

    International Nuclear Information System (INIS)

    Stafford, D.S.

    2015-01-01

    In light water reactor fuel rods, waterside corrosion of zirconium-alloy cladding introduces hydrogen into the cladding, where it is slightly soluble. When the solubility limit is reached, the hydrogen precipitates into crystals of zirconium hydride which decrease the ductility of the cladding and may lead to cladding failure during dry storage or transportation events. The distribution of the hydride phase and the orientation of the crystals depend on the history of the spatial temperature and stress profiles in the cladding. In this work, we have expanded the existing hydride modeling capability in the BISON fuel performance code with the goal of predicting both global and local effects on the radial, azimuthal and axial distribution of the hydride phase. We compare results from 1D simulations to published experimental data. We demonstrate the new capability by simulating in 2D a fuel rod throughout a lifecycle that includes irradiation, short-term storage in the spent fuel pool, drying, and interim storage in a dry cask. Using the 2D simulations, we present qualitative predictions of the effects of the inter-pellet gap and the drying conditions on the growth of a hydride rim. - Highlights: • We extend BISON fuel performance code to simulate lifecycle of fuel rods. • We model hydrogen evolution in cladding from reactor through dry storage. • We validate 1D simulations of hydrogen evolution against experiments. • We show results of 2D axisymmetric simulations predicting hydride formation. • We show how our model predicts formation of a hydride rim in the cladding.

  17. Heavy metal sorption by microalgae

    International Nuclear Information System (INIS)

    Sandau, E.; Sandau, P.; Pulz, O.

    1996-01-01

    Viable microalgae are known to be able to accumulate heavy metals (bioaccumulation). Against a background of the increasing environmental risks caused by heavy metals, the microalgae Chlorella vulgaris and Spirulina platensis and their potential for the biological removal of heavy metals from aqueous solutions were taken as an example for investigation. Small-scale cultivation tests (50 l) with Cd-resistant cells of Chlorella vulgaris have shown that approx. 40% of the added 10 mg Cd/l was removed from the solution within seven days. At this heavy metal concentration sensitive cells died. Non-viable microalgae are able to eliminate heavy metal ions in a short time by biosorption in uncomplicated systems, without any toxicity problems. Compared with original biomasses, the sorption capacity of microalgal by-products changes only insignificantly. Their low price makes them economical. (orig.)

  18. Hydriding and neutron irradiation in zircaloy-4

    International Nuclear Information System (INIS)

    Ramos, Ruben Fortunato; Martin, Juan Ezequiel; Orellano, Pablo; Dorao, Carlos; Analia Soldati; Ghilarducci, Ada Albertina; Corso, Hugo Luis; Peretti, Hernan Americo; Bolcich, Juan Carlos

    2003-01-01

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

  19. Optical and photoemission studies of lanthanum hydrides

    International Nuclear Information System (INIS)

    Peterman, D.J.; Peterson, D.T.; Weaver, J.H.

    1980-01-01

    The results of optical absorptivity and photoemission measurements on lanthanum hydrides, LaH/sub x/ (1.98 less than or equal to x less than or equal to 2.89) are reported. The low energy (hν less than or equal to 0.5 eV) optical features in LaH/sub x/ are attributed to the filling of octahedral sites. Higher energy interband absorption involves states within the d-band complex, analogous to other dihydrides. As x increases above 2.0, the optical features change rapidly due to the increase in the number of occupied octahedral sites. Various band structure studies suggest that LaH 3 might be a semiconductor. Photoemission results show that as x increases, the d-derived states at E/sub F/ are drawn down and that for LaH 2 89 only very weak valence band emission is observed. The hydrogen-derived bonding bands are shown centered approx. 5 eV below E/sub F/. Observed chemical shifts in the La 5p/sub 1/2 3/2/ cores are discussed for 1.98 less than or equal to x less than or equal to 2.89

  20. Metal Sorption to Dolomite Surfaces

    International Nuclear Information System (INIS)

    Brady, P.V.; Papenguth, H.W.; Kelly, J.W.

    1999-01-01

    Potential human intrusion into the Waste Isolation Pilot Plant (WIPP) might release actinides into the Culebra Dolomite where sorption reactions will affect of radiotoxicity from the repository. Using a limited residence time reactor the authors have measured Ca, Mg, Nd adsorption/exchange as a function of ionic strength, P CO2 , and pH at 25 C. By the same approach, but using as input radioactive tracers, adsorption/exchange of Am, Pu, U, and Np on dolomite were measured as a function of ionic strength, P CO2 , and pH at 25 C. Metal adsorption is typically favored at high pH. Calcium and Mg adsorb in near-stoichiometric proportions except at high pH. Adsorption of Ca and Mg is diminished at high ionic strengths (e.g., 0.5M NaCl) pointing to association of Na + with the dolomite surface, and the possibility that Ca and Mg sorb as hydrated, outer-sphere complexes. Sulfate amplifies sorption of Ca and Mg, and possibly Nd as well. Exchange of Nd for surface Ca is favored at high pH, and when Ca levels are low. Exchange for Ca appears to control attachment of actinides to dolomite as well, and high levels of Ca 2+ in solution will decrease Kds. At the same time, to the extent that high P CO2 increase Ca 2+ levels, JK d s will decrease with CO 2 levels as well, but only if sorbing actinide-carbonate complexes are not observed to form (Am-carbonate complexes appear to sorb; Pu-complexes might sorb as well; U-carbonate complexation leads to desorption). This indirect CO 2 effect is observed primarily at, and above, neutral pH. High NaCl levels do not appear to affect to actinide K d s

  1. Bed system performance in helium circulation mode

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-05-15

    As a part of the International Thermonuclear Experimental Reactor (ITER) Project, We have conducted an experiment for storing hydrogen to depleted uranium and zirconium cobalt. The helium blanket effect has been observed in experiments using metal hydrides. The collapse of the hydrogen isotopes are accompanied by the decay heat and helium-3. Helium-3 dramatically reduces the hydrogen isotope storage capacity by surrounding the metal. This phenomenon is called a helium blanket effect. In addition the authors are working on the recovery and removal techniques of helium-3. In this paper, we discuss the equipment used to test the helium blanket effect and the results of a helium circulation experiment. The helium-3 produced surrounds the storage material surface and thus disturbs the reaction of the storage material and the hydrogen isotope. Even if the amount of helium-3 is small, the storage capacity of the SDS bed significantly drops. This phenomenon is the helium blanket effect. To resolve this phenomenon, a circulating loop was introduced. Using a circulating system, helium can be separated from the storage material. We made a helium loop that includes a ZrCo bed. Then using a metal bellows pump, we tested the helium circulation.

  2. Sorption of methylxanthines by different sorbents

    Science.gov (United States)

    Dmitrienko, S. G.; Andreeva, E. Yu.; Tolmacheva, V. V.; Terent'eva, E. A.

    2013-05-01

    Sorption of caffeine, theophylline, theobromine, diprophylline, and pentoxyphylline on different sorbents (supercross-linked polystyrene, surface-modified copolymer of styrene and divinylbenzene Strata-X, and carbon nanomaterials Taunit and Diasorb-100-C16T) was studied in a static mode in an effort to find new sorbents suitable for sorption isolation and concentration of methylxanthines. The peculiarities of sorption of methylxanthines were explained in relation to the solution acidity, the nature of the sorbates and their concentration, the nature of the solvent, and the structural characteristics of the sorbents.

  3. Sorption isolation of strontium from seawater

    International Nuclear Information System (INIS)

    Avramenko, V.A.; Zheleznov, V.V.; Kaplun, E.V.; Sokol'nitskaya, T.A.; Yukhkam, A.A.

    2001-01-01

    Sorption isolation of strontium from seawater is considered and prospects of use of selective adsorbents for purification of seawater or liquid radioactive wastes mixed with seawater from 90 Sr are discussed. Comparative analysis of sorptive properties of adsorbents of different nature is done. It is shown that sorption-reagent materials developed by authors can to afford effective separation of 90 Sr from seawater. Possible mechanism of strontium sorption by these adsorbents is considered. The prospect of their use for purification of liquid radioactive wastes from strontium is shown [ru

  4. Immobilization of inorganic ion-exchanger into bio-polymer foams - Application to cesium sorption

    International Nuclear Information System (INIS)

    Vincent, Chloe; Hertz, Audrey; Barre, Yves; Vincent, Thierry; Guibal, Eric

    2014-01-01

    Nickel-potassium ferrocyanide (along with other ferrocyanide sub-products, as shown by mineralization, SEM-EDX and XRD analyses) has been immobilized in highly porous discs of chitin for the sorption of Cs(I) from near neutral solutions. The immobilization process allows synthesizing stable materials that can bind up to 80 mg Cs g -1 (i.e., 240 mg Cs g -1 ion-exchanger). Cesium sorption is hardly affected by the pH between pH 2 and 8. The sorbent is selective to Cs(I) even in the presence of high concentrations of Na(I), K(I), Rb(I) or NH 4+ . The pseudo-second order rate equation fits well kinetic profiles: the rate coefficient increases with the flow rate of recirculation (to force the access to potentially non-interconnected pores), as an evidence of the control of uptake kinetics by diffusion properties. In fixed-bed columns, the breakthrough curve is accurately described by the Clark model and the sorption capacity (at sorbent saturation) is consistent with the values obtained in sorption isotherms. Preliminary tests performed on 137 Cs spiked solutions confirm the efficiency of the material for the treatment of effluents bearing radionuclides. (authors)

  5. The effect of TTNT nanotubes on hydrogen sorption using MgH2

    Directory of Open Access Journals (Sweden)

    Mariana Coutinho Brum

    2013-06-01

    Full Text Available Nanotubes are promising materials to be used with magnesium hydride, as catalysts, in order to enhance hydrogen sorption. A study was performed on the hydrogen absorption/desorption properties of MgH2 with the addition of TTNT (TiTanate NanoTubes. The MgH2-TTNT composite was prepared by ball milling and the influence of the TTNT amount (1.0 and 5.0 wt. (% on the hydrogen capacity was evaluated. The milling of pure MgH2 was performed for 24 hours and afterwards the MgH2-TTNT composite was milled for 20 minutes. Transmission Electronic Microscopy (TEM and Scanning Electron Microscopy (SEM were used to evaluate the nanotube synthesis and show the particle morphology of the MgH2-TTNT composite, respectively. The Differential Scanning Calorimetry (DSC examination provided some evidence with the shifting of the peaks obtained when the amount of TTNT is increased. The hydrogen absorption/desorption kinetics tests showed that the TTNT nanotubes can enhance hydrogen sorption effectively and the total hydrogen capacity obtained was 6.5 wt. (%.

  6. The effect of TTNT nanotubes on hydrogen sorption using MgH{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Brum, Mariana Coutinho; Jardim, Paula Mendes; Conceicao, Monique Osorio Talarico da; Santos, Dilson Silva dos, E-mail: monique@metalmat.ufrj.br [Coordenacao dos Programas de Pos-Graduacao em Engenharia (PEMM/COPPEP/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Metalurgica e de Materiais

    2013-11-01

    Nanotubes are promising materials to be used with magnesium hydride, as catalysts, in order to enhance hydrogen sorption. A study was performed on the hydrogen absorption/desorption properties of MgH{sub 2} with the addition of TTNT (TiTanate nanotubes). The MgH{sub 2} -TTNT composite was prepared by ball milling and the influence of the TTNT amount (1.0 and 5.0 wt. (%)) on the hydrogen capacity was evaluated. The milling of pure MgH{sub 2} was performed for 24 hours and afterwards the MgH{sub 2} -TTNT composite was milled for 20 minutes. Transmission Electronic Microscopy (TEM) and Scanning Electron Microscopy (SEM) were used to evaluate the nanotube synthesis and show the particle morphology of the MgH{sub 2} -TTNT composite, respectively. The Differential Scanning Calorimetry (DSC) examination provided some evidence with the shifting of the peaks obtained when the amount of TTNT is increased. The hydrogen absorption/desorption kinetics tests showed that the TTNT nanotubes can enhance hydrogen sorption effectively and the total hydrogen capacity obtained was 6.5 wt. (%). (author)

  7. The effect of TTNT nanotubes on hydrogen sorption using MgH2

    International Nuclear Information System (INIS)

    Brum, Mariana Coutinho; Jardim, Paula Mendes; Conceicao, Monique Osorio Talarico da; Santos, Dilson Silva dos

    2013-01-01

    Nanotubes are promising materials to be used with magnesium hydride, as catalysts, in order to enhance hydrogen sorption. A study was performed on the hydrogen absorption/desorption properties of MgH 2 with the addition of TTNT (TiTanate nanotubes). The MgH 2 -TTNT composite was prepared by ball milling and the influence of the TTNT amount (1.0 and 5.0 wt. (%)) on the hydrogen capacity was evaluated. The milling of pure MgH 2 was performed for 24 hours and afterwards the MgH 2 -TTNT composite was milled for 20 minutes. Transmission Electronic Microscopy (TEM) and Scanning Electron Microscopy (SEM) were used to evaluate the nanotube synthesis and show the particle morphology of the MgH 2 -TTNT composite, respectively. The Differential Scanning Calorimetry (DSC) examination provided some evidence with the shifting of the peaks obtained when the amount of TTNT is increased. The hydrogen absorption/desorption kinetics tests showed that the TTNT nanotubes can enhance hydrogen sorption effectively and the total hydrogen capacity obtained was 6.5 wt. (%). (author)

  8. Hydrogen storage as a hydride. Citations from the International Aerospace Abstracts data base

    Science.gov (United States)

    Zollars, G. F.

    1980-01-01

    These citations from the international literature concern the storage of hydrogen in various metal hydrides. Binary and intermetallic hydrides are considered. Specific alloys discussed are iron titanium, lanthanium nickel, magnesium copper and magnesium nickel among others.

  9. The effect of stress state on zirconium hydride reorientation

    Science.gov (United States)

    Cinbiz, Mahmut Nedim

    Prior to storage in a dry-cask facility, spent nuclear fuel must undergo a vacuum drying cycle during which the spent fuel rods are heated up to elevated temperatures of ≤ 400°C to remove moisture the canisters within the cask. As temperature increases during heating, some of the hydride particles within the cladding dissolve while the internal gas pressure in fuel rods increases generating multi-axial hoop and axial stresses in the closed-end thin-walled cladding tubes. As cool-down starts, the hydrogen in solid solution precipitates as hydride platelets, and if the multiaxial stresses are sufficiently large, the precipitating hydrides reorient from their initial circumferential orientation to radial orientation. Radial hydrides can severely embrittle the spent nuclear fuel cladding at low temperature in response to hoop stress loading. Because the cladding can experience a range of stress states during the thermo-mechanical treatment induced during vacuum drying, this study has investigated the effect of stress state on the process of hydride reorientation during controlled thermo-mechanical treatments utilizing the combination of in situ X-ray diffraction and novel mechanical testing analyzed by the combination of metallography and finite element analysis. The study used cold worked and stress relieved Zircaloy-4 sheet containing approx. 180 wt. ppm hydrogen as its material basis. The failure behavior of this material containing radial hydrides was also studied over a range of temperatures. Finally, samples from reactor-irradiated cladding tubes were examined by X-ray diffraction using synchrotron radiation. To reveal the stress state effect on hydride reorientation, the critical threshold stress to reorient hydrides was determined by designing novel mechanical test samples which produce a range of stress states from uniaxial to "near-equibiaxial" tension when a load is applied. The threshold stress was determined after thermo-mechanical treatments by

  10. Precipitation of γ-zirconium hydride in zirconium

    International Nuclear Information System (INIS)

    Carpenter, G.J.C.

    1978-01-01

    A mechanism for the precipitation of γ-zirconium hydride in zirconium is presented which does not require the diffusion of zirconium. The transformation is completed by shears caused by 1/3 (10 anti 10) Shockley partial dislocations on alternate zirconium basal planes, either by homogeneous nucleation or at lattice imperfections. Homogeneous nucleation is considered least likely in view of the large nucleation barrier involved. Hydrides may form at dislocations by the generation of partials by means of either a pole or ratchet mechanism. The former requires dislocations with a component of Burgers vector along the c-axis, but contrast experiments show that these are not normally observed in annealed zirconium. It is therefore most likely that intragranular hydrides form at the regular 1/3 (11 anti 20) dislocations, possibly by means of a ratchet mechanism. Contrast experiments in the electron microscope show that the precipitates have a shear character consistent with the mechanism suggested. The possibility that the shear dislocations associated with the hydrides are emissary dislocations is considered and a model suggested in which this function is satisfied together with the partial relief of misfit stresses. The large shear strains associated with the precipitation mechanism may play an important role in the preferential orientation of hydrides under stress

  11. Sodium-based hydrides for thermal energy applications

    Science.gov (United States)

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

    2016-04-01

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

  12. Mechanisms of hydrogen induced delayed cracking in hydride forming materials

    International Nuclear Information System (INIS)

    Dutton, R.; Nuttall, K.; Puls, M.P.; Simpson, L.A.

    1977-01-01

    Mechanisms which have been formulated to describe delayed hydrogen cracking in hydride-forming metals are reviewed and discussed. Particular emphasis is placed on the commercial alloy Zr--2.5% Nb (Cb) which is extensively used in nuclear reactor core components. A quantitative model for hydrogen cracking in this material is presented and compared with available experimental data. The kinetics of crack propagation are controlled by the growth of hydrides at the stressed crack tip by the diffusive ingress of hydrogen into this region. The driving force for the diffusion flux is provided by the local stress gradient which interacts with both hydrogen atoms in solution and hydrogen atoms being dissolved and reprecipitated at the crack tip. The model is developed using concepts of elastoplastic fracture mechanics. Stage I crack growth is controlled by hydrides growing in the elastic stress gradient, while Stage II is controlled by hydride growth in the plastic zone at the crack tip. Recent experimental observations are presented which indicate that the process occurs in an intermittent fashion; hydride clusters accumulate at the crack tip followed by unstable crack advance and subsequent crack arrest in repeated cycles

  13. Mechanisms of hydrogen induced delayed cracking in hydride forming materials

    International Nuclear Information System (INIS)

    Dutton, R.; Nuttall, K.; Puls, M.P.; Simpson, L.A.

    1977-01-01

    Mechanisms which have been formulated to describe delayed hydrogen cracking in hydride-forming metals are reviewed and discussed. Particular emphasis is placed on the commercial alloy Zr-2.5 pct Nb which is extensively used in nuclear reactor core components. A quantitative model for hydrogen cracking in this material is presented and compared with available experimental data. The kinetics of crack propagation are controlled by the growth of hydrides at the stressed crack tip by the diffusive ingress of hydrogen into this region. The driving force for the diffusion flux is provided by the local stress gradient which interacts with both hydrogen atoms in solution and hydrogen atoms being dissolved and reprecipitated at the crack tip. The model is developed using concepts of elastoplastic fracture mechanics. Stage I crack growth is controlled by hydrides growing in the elastic stress gradient, while Stage II is controlled by hydride growth in the plastic zone at the crack tip. Recent experimental observations are presented which indicate that the process occurs in an intermittent fashion; hydride clusters accumulate at the crack tip followed by unstable crack advance and subsequent crack arrest in repeated cycles. 55 refs., 6 figs

  14. PCB congener sorption to carbonaceous sediment components: Macroscopic comparison and characterization of sorption kinetics and mechanism

    International Nuclear Information System (INIS)

    Choi, Hyeok; Al-Abed, Souhail R.

    2009-01-01

    Sorption of polychlorinated biphenyls (PCBs) to sediment is a key process in determining their mobility, bioavailability, and chemical decomposition in aquatic environments. In order to examine the validity of currently used interpretation approaches for PCBs sorption, comparative results on 2-chlorobiphenyl sorption to carbonaceous components in sediments (activated carbon, carbon black, coal, soot, graphite, flyash, wood) were macroscopically correlated with the structural, morphological, crystallographic, and compositional properties of the carbonaceous components. Since the Freundlich sorption constant, K F (L kg -1 ) spanned several orders of magnitude, ranging from log K F of 6.13-5.27 for activated carbon, 5.04 for carbon black, 3.83 for coal to 3.08 for wood, organic carbon partitioning approach should be more specifically categorized, considering the various forms, nature and origins of organic carbon in sediment. Sorption rate constants and fraction parameters, which were numerically defined from empirical kinetic model with fast and slow sorption fractions, were closely related to the physicochemical properties of the carbonaceous components. Sorption interpretation approaches with a specific property and viewpoint, such as organic carbon partitioning, soot carbon distribution, or surface area correlation, did not properly explain the overall results on sorption capacity, fast and slow sorption kinetics, and partitioning coefficient. It is also important to emphasize the heterogeneous nature of sediment and the difficulties of encompassing the partitioning among its carbonaceous components.

  15. PCB congener sorption to carbonaceous sediment components: Macroscopic comparison and characterization of sorption kinetics and mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Hyeok [National Risk Management Research Laboratory, U.S. Environmental Protection Agency, 26 West Martin Luther King Drive, Cincinnati, OH 45268 (United States); Al-Abed, Souhail R., E-mail: al-abed.souhail@epa.gov [National Risk Management Research Laboratory, U.S. Environmental Protection Agency, 26 West Martin Luther King Drive, Cincinnati, OH 45268 (United States)

    2009-06-15

    Sorption of polychlorinated biphenyls (PCBs) to sediment is a key process in determining their mobility, bioavailability, and chemical decomposition in aquatic environments. In order to examine the validity of currently used interpretation approaches for PCBs sorption, comparative results on 2-chlorobiphenyl sorption to carbonaceous components in sediments (activated carbon, carbon black, coal, soot, graphite, flyash, wood) were macroscopically correlated with the structural, morphological, crystallographic, and compositional properties of the carbonaceous components. Since the Freundlich sorption constant, K{sub F} (L kg{sup -1}) spanned several orders of magnitude, ranging from log K{sub F} of 6.13-5.27 for activated carbon, 5.04 for carbon black, 3.83 for coal to 3.08 for wood, organic carbon partitioning approach should be more specifically categorized, considering the various forms, nature and origins of organic carbon in sediment. Sorption rate constants and fraction parameters, which were numerically defined from empirical kinetic model with fast and slow sorption fractions, were closely related to the physicochemical properties of the carbonaceous components. Sorption interpretation approaches with a specific property and viewpoint, such as organic carbon partitioning, soot carbon distribution, or surface area correlation, did not properly explain the overall results on sorption capacity, fast and slow sorption kinetics, and partitioning coefficient. It is also important to emphasize the heterogeneous nature of sediment and the difficulties of encompassing the partitioning among its carbonaceous components.

  16. Screening of metal hydride pairs for closed thermal energy storage systems

    International Nuclear Information System (INIS)

    Aswin, N.; Dutta, Pradip; Murthy, S. Srinivasa

    2016-01-01

    Thermal energy storage systems based on metal/hydrides usually are closed systems composed of two beds of metal/alloy – one meant for energy storage and the other for hydrogen storage. It can be shown that a feasible operating cycle for such a system using a pair of metals/alloys operating between specified temperature values can be ensured if the equilibrium hydrogen intake characteristics satisfy certain criteria. In addition, application of first law of thermodynamics to an idealized operating cycle can provide the upper bounds of selected performance indices, namely volumetric energy storage density, energy storage efficiency and peak discharge temperature. This is demonstrated for a representative system composed of LaNi 4.7 Al 0.3 –LaNi 5 operating between 353 K and 303 K which gave values of about 56 kW h m −3 for volumetric storage density, about 85% for energy storage efficiency and 343 K for peak discharge temperature. A system level heat and mass transfer study considering the reaction kinetics, hydrogen flow between the beds and heat exchanger models is presented which gave second level estimates of about 40 kW h m −3 for volumetric energy storage density, 73% for energy storage efficiency and 334 K for peak temperature for the representative system. The results from such studies lead to identifying metal/alloy pairs which can be shortlisted for detailed studies.

  17. Carbon dioxide sorption on EDTA modified halloysite

    Directory of Open Access Journals (Sweden)

    Waszczuk Patrycja

    2016-01-01

    Full Text Available In this paper the sorption study of CO2 on EDTA surface modified halloysite was conducted. In the paper chemical modification of halloysite from the Dunino deposit (Poland and its influence on sorption of CO2 are presented. A halloysite samples were washed with water-EDTA 1% solution, centrifuged to separate liquid and impurities and dried. The samples were tested for the sorption capacity using a manometric method with pressure up to 3 MPa. A Langmuir adsorption model was fitted to the data. The results showed that EDTA had a limited effect on the increase of sorption potential at low pressure and the samples exhibited similar results to that ones treated solely with the water solution.

  18. Sorption of metaldehyde using granular activated carbon

    Directory of Open Access Journals (Sweden)

    S. Salvestrini

    2017-09-01

    Full Text Available In this work, the ability of granular activated carbon (GAC to sorb metaldehyde was evaluated. The kinetic data could be described by an intra-particle diffusion model, which indicated that the porosity of the sorbent strongly influenced the rate of sorption. The analysis of the equilibrium sorption data revealed that ionic strength and temperature did not play any significant role in the metaldehyde uptake. The sorption isotherms were successfully predicted by the Freundlich model. The GAC used in this paper exhibited a higher affinity and sorption capacity for metaldehyde with respect to other GACs studied in previous works, probably as a result of its higher specific surface area and high point of zero charge.

  19. Study of sorption of technetium on pyrrhotine

    International Nuclear Information System (INIS)

    Shen Dong; Fan Xianhua; Su Xiguang; Zeng Jishu

    2001-01-01

    The sorption behaviors of technetium on pyrrhotine are studied with batch experiment and dilute sulfuric acid is used to dissolve the technetium adsorbed on pyrrhotine. Sorption and desorption experiment are performed under aerobic and anaerobic conditions (inert gas box). The results show that a significant sorption of technetium on pyrrhotine is found under aerobic and anaerobic conditions, and the sorption on the mineral is supposed to be due to the reduction of TcO 4 - to insoluble TcO 2 ·nH 2 O. Desorption process of the sorbed technetium into dilute sulfuric acid is found to be different under aerobic and anaerobic conditions. On addition of H 2 O 2 to the leach solution a sudden increase of the technetium concentration is observed

  20. Radionuclide sorption on granitic drill core material

    International Nuclear Information System (INIS)

    Eriksen, T.E.; Locklund, B.

    1987-11-01

    Distribution ratios were determined for Sr-85, Cs-134 and Eu-152 on crushed granite and fissure coating/filling material from Stripa mines. Measurements were also carried out on intact fissure surfaces. The experimental data for Sr-85, Cs-134 on crushed material can be accomodated by a sorption model based on the assumption that the crushed material consists of porous spheres with outer and inner surfaces available for sorption. In the case of Eu-152 only sorption on the outer surfaces of the crushed material was observed. The absence of sorption on inner surfaces is most probably due to high depletion of the more strongly sorbed Eu-152 in the water phase and very low diffusivity of Eu-152 in the sorbed state. (orig./HP)

  1. Sorption of heteropoly acids by polyurethane foam

    International Nuclear Information System (INIS)

    Dmitreinko, S.G.; Goncharova, L.V.; Runov, V.K.; Zakharov, V.N.; Aslanova, L.A.

    1997-01-01

    Sorption of oxidized and reduced forms of molybdosilicic, molybdophosphoric and molybdovanadophosphoric acids by polyurethane foam based on ethers and esters is studied. On the basis of sorption dependence on solution pH, polyurethane foam type and spectral characteristics of sorbates the suggestion has been made that in the polyurethane foam phase there are two main types of sorbent-sorbate interaction: electrostatic (ion-ion) and with hydrogen bond formation: and it is impossible to determine the contribution of every interaction

  2. Sorption of organophosphate esters by carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Wei; Yan, Li [State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085 (China); Duan, Jinming [School of Environmental and Municipal Engineering, Xi’an University of Architecture and Technology, Xi’an 710055 (China); Jing, Chuanyong, E-mail: cyjing@rcees.ac.cn [State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085 (China)

    2014-05-01

    Graphical abstract: The interfacial interactions between the OPE molecules and CNTs. - Highlights: • Oxygen-containing groups on CNTs change the sorption property for OPEs. • Molecular configuration of OPEs has insignificant impact on their sorption. • Hydrophobic, π–π EDA and Brønsted acid–base interaction occurred between the CNTs and OPEs. - Abstract: Insights from the molecular-level mechanism of sorption of organophosphate esters (OPEs) on carbon nanotubes (CNTs) can further our understanding of the fate and transport of OPEs in the environment. The motivation for our study was to explore the sorption process of OPEs on multi-walled CNTs (MWCNTs), single-walled CNTs (SWCNTs) and their oxidized counterparts (O-MWCNTs and O-SWCNTs), and its molecular mechanism over a wide concentration range. The sorption isotherm results revealed that the hydrophobicity of OPEs dominated their affinities on a given CNT and the π–π electron donor–acceptor (EDA) interaction also played an important role in the sorption of aromatic OPEs. This π–π EDA interaction, verified with Raman and FT-IR spectroscopy, could restrict the radial vibration of SWCNTs and affect the deformation vibration γ(CH) bands of OPE molecules. The OPE surface coverage on CNTs, estimated using the nonlinear Dubinin–Ashtakhov model, indicated that the oxygen-containing functional groups on CNTs could interact with water molecules by H-bonding, resulting in a decrease in effective sorption sites. In addition, FTIR analysis also confirmed the occurrence of Brønsted acid–base interactions between OPEs and surface OH groups of SWCNTs. Our results should provide mechanistic insights into the sorption mechanism of OPE contaminants on CNTs.

  3. Sorption of cesium and uranium to Feldspar

    International Nuclear Information System (INIS)

    Wijland, G.C.; Pennders, R.M.J.

    1990-07-01

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

  4. Sorption of fomesafen in Brazilian soils

    OpenAIRE

    Silva,G.R.; D'Antonino,L.; Faustino,L.A.; Silva,A.A.; Ferreira,F.A.; Texeira,C.C.

    2013-01-01

    The study of the dynamics of a herbicide in the soil focus on the interactions with environmental components to obtain agronomic efficiency, ensuring selectivity to the culture and risk reduction of environmental impact. This study evaluated the sorption process of fomesafen in the Brazilian soils Ultisol, Cambisol, and Organosol. Besides soil, washed sand was used as an inert material for determination of the sorption ratio of fomesafen in the soil. The bioassay method was applied, using Sor...

  5. Kinetics of strontium sorption in calcium phosphate

    International Nuclear Information System (INIS)

    Bacic, S.; Komarov, V.F.; Vukovic, Z.

    1989-01-01

    Kinetics of strontium sorption by highly dispersed solids: tricalcium phosphate (Ca 3 (PO 4 ) 2 , TCP) and hydroxyapatite (Ca 5 (PO 4 ) 3 )H, HAP) were investigated. Analysis of sorption data was made taking into consideration composition and morphology of ultra micro particles. Conclusion is that the isomorphous strontium impurity is structurally sensitive element for calcium phosphate. It was determined that the beginning of strontium desorption corresponds to the beginning of transformation of the TCP - HAP (author)

  6. Simultaneous determination of hydride and non-hydride forming elements by inductively coupled plasma optical emission spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Benzo, Z. [Instituto Venezolano de Investigaciones Cientificas, IVIC, Altos de Pipe, Caracas (Venezuela, Bolivarian Republic of); Matos-Reyes, M.N.; Cervera, M.L.; Guardia, M. de la, E-mail: m.luisa.cervera@uv.es [Department of Analytical Chemistry, University of Valencia, Valencia (Spain)

    2011-09-15

    The operating characteristics of a dual nebulization system were studied including instrumental and chemical conditions for the hydride generation and analytical figures of merit for both, hydride and non hydride forming elements. Analytical performance of the nebulization system was characterized by detection limits from 0.002 to 0.0026 {mu}g mL{sup -1} for the hydride forming elements and between 0.0034 and 0.0121 {mu}g mL{sup -1} for the non-hydride forming elements, relative standard deviation for 10 replicate measurements at 0.25 mg L{sup -1} level and recovery percentages between 97 and 103%. The feasibility of the system was demonstrated in the simultaneous determination of Ca, Cd, Co, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Zn, As, Bi, Sb, Se, and Te in the NIST 1549 (non-fat milk powder), NIST 1570a (spinach leaves), DORM-2 (dogfish muscle) and TORT-2 (lobster hepatopancreas) certified samples for trace elements. Results found were in good agreement with the certified ones. (author)

  7. Infrared diode laser spectroscopy of lithium hydride

    International Nuclear Information System (INIS)

    Yamada, C.; Hirota, E.

    1988-01-01

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

  8. A fractographic distinction between hydride cracking and stress corrosion cracking in zircaloys

    International Nuclear Information System (INIS)

    Cox, B.

    1978-06-01

    The fractographic details of SCC and delayed hydride failures are compared by scanning and replica electron microscopy. It is shown that there are distinct features ascribable to the fracture of hydride platelets which are absent from SCC fractures and which distinguish them from fractures produced by delayed hydride cracking. (author)

  9. Use of triammonium salt of aurin tricarboxylic acid as risk mitigant for aluminum hydride

    Science.gov (United States)

    Cortes-Concepcion, Jose A.; Anton, Donald L.

    2017-08-08

    A process and a resulting product by process of an aluminum hydride which is modified with by physically combining in a ball milling process an aluminum hydride with a triammonium salt of aurin tricarboxylic acid. The resulting product is an aluminum hydride which is resistant to air, ambient moisture, and liquid water while maintaining useful hydrogen storage and release kinetics.

  10. A computer model for hydride blister growth in zirconium alloys

    International Nuclear Information System (INIS)

    White, A.J.; Sawatzky, A.; Woo, C.H.

    1985-06-01

    The failure of a Zircaloy-2 pressure tube in the Pickering unit 2 reactor started at a series of zirconium hydride blisters on the outside of the pressure tube. These blisters resulted from the thermal diffusion of hydrogen to the cooler regions of the pressure tube. In this report the physics of thermal diffusion of hydrogen in zirconium is reviewed and a computer model for blister growth in two-dimensional Cartesian geometry is described. The model is used to show that the blister-growth rate in a two-phase zirconium/zirconium-hydride region does not depend on the initial hydrogen concentration nor on the hydrogen pick-up rate, and that for a fixed far-field temperature there is an optimum pressure-type/calandria-tube contact temperature for growing blisters. The model described here can also be used to study large-scale effects, such as hydrogen-depletion zones around hydride blisters

  11. Hydrides and deuterides of lithium and sodium. Pt. 1

    International Nuclear Information System (INIS)

    Haque, E.

    1990-01-01

    An interionic potential model is developed for lighter and heavier alkali hydrides and deuterides. The method uses a combination of theoretical techniques, empirical fit, and a few plausible assumptions. An assessment of the derived potentials is made by calculating the lattice statics and dynamics of the crystals and by comparing both with experiment (where available) and with other calculations. The potentials are found to describe the elastic and dielectric properties reasonably well. The phonon dispersion curves of hydride and deuteride of sodium are compared with the calculations of Dyck and Jex based on force constant model approach and the results are discussed. The need for further experiments on heavier hydrides and deuterides is stressed. (author)

  12. Research in Nickel/Metal Hydride Batteries 2017

    Directory of Open Access Journals (Sweden)

    Kwo-Hsiung Young

    2018-02-01

    Full Text Available Continuing from a special issue in Batteries in 2016, nineteen new papers focusing on recent research activities in the field of nickel/metal hydride (Ni/MH batteries have been selected for the 2017 Special Issue of Ni/MH Batteries. These papers summarize the international joint-efforts in Ni/MH battery research from BASF, Wayne State University, Michigan State University, FDK Corp. (Japan, Institute for Energy Technology (Norway, Central South University (China, University of Science and Technology Beijing (China, Zhengzhou University of Light Industry (China, Inner Mongolia University of Science and Technology (China, Shenzhen Highpower (China, and University of the Witwatersrand (South Africa from 2016–2017 through reviews of AB2 metal hydride alloys, Chinese and EU Patent Applications, as well as descriptions of research results in metal hydride alloys, nickel hydroxide, electrolyte, and new cell type, comparison work, and projections of future works.

  13. New ternary hydride formation in U-Ti-H system

    International Nuclear Information System (INIS)

    Yamamoto, Takuya; Kayano, Hideo; Yamawaki, Michio.

    1991-01-01

    Hydrogen absorption properties of two titanium-rich uranium alloys, UTi 2 and UTi 4 , were studied in order to prepare and identify the recently found ternary hydride. They slowly reacted with hydrogen of the initial pressure of 10 5 Pa at 873K to form the ternary hydride. The hydrogenated specimen mainly consisted of the pursued ternary hydride but contained also U(or UO 2 ), TiH x , and some transient phases. X-ray powder diffraction and Electron Probe Micro Analysis proved that it was the UTi 2 H x with the expected MgCu 2 structure, though all the X-ray peaks were broad probably because of inhomogeneity. This compound had extremely high resistance to powdering on its formation, which showed high potential utilities for a non-powdering tritium storage system or for other purposes. (author)

  14. Iodine sorption by microwave irradiated hydrotalcites

    Energy Technology Data Exchange (ETDEWEB)

    Paredes, S.P. [Universidad Autonoma de Puebla, Facultad de Ciencias Quimicas, C.P. 72570, Puebla, Pue (Mexico); Instituto Politecnico Nacional, ESIQIE, C.P. 07738, Mexico, D.F. (Mexico); Fetter, G. [Universidad Autonoma de Puebla, Facultad de Ciencias Quimicas, C.P. 72570, Puebla, Pue (Mexico)]. E-mail: geolarfetter@yahoo.com.mx; Bosch, P. [Universidad Nacional Autonoma de Mexico, Instituto de Investigaciones en Materiales, C.P. 04510, Mexico, D.F. (Mexico); Bulbulian, S. [Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, C.P. 11801, Mexico, D.F. (Mexico)

    2006-12-15

    Mg-Al hydrotalcite-like compounds (HT) were prepared by the microwave method on the one hand with ethoxide-acetylacetonate and on the other with acetylacetonate as precursors. They presented a maximum sorption capacity of 2.179 and 1.517 meq of {sup 131}I{sup -}/g of hydrotalcite respectively. When the hydrotalcites were calcined and rehydrated in a {sup 131}I{sup -} solution, iodine sorption decreased in both samples to 1.515 and 1.446, respectively. The corresponding value for nitrated hydrotalcite which was prepared by the conventional method for comparison purposes, was 0.570. The radionuclide content in hydrotalcites was determined by {gamma}-spectrometry. {sup 131}I{sup -} sorption is dependent on two main parameters: one is the type of the interlayer organic material and the second the surface area. It was found that hydrotalcites prepared with ethoxide-acetylacetonate were better sorbents for {sup 131}I{sup -} than those with acetylacetonate. Still, if the specific surface area increased, {sup 131}I{sup -}sorption increased as well; nitrated HT resulted in low specific surface area and a low sorption capacity. It is, therefore, concluded that organic residues present in the samples prepared by the microwave method favor the sorption of radioactive anions, in particular {sup 131}I{sup -} if compared with nitrated and/or carbonate interlayered hydrotalcites.

  15. Migration and sorption phenomena in packaged foods.

    Science.gov (United States)

    Gnanasekharan, V; Floros, J D

    1997-10-01

    Rapidly developing analytical capabilities and continuously evolving stringent regulations have made food/package interactions a subject of intense research. This article focuses on: (1) the migration of package components such as oligomers and monomers, processing aids, additives, and residual reactants in to packaged foods, and (2) sorption of food components such as flavors, lipids, and moisture into packages. Principles of diffusion and thermodynamics are utilized to describe the mathematics of migration and sorption. Mathematical models are developed from first principles, and their applicability is illustrated using numerical simulations and published data. Simulations indicate that available models are system (polymer-penetrant) specific. Furthermore, some models best describe the early stages of migration/sorption, whereas others should be used for the late stages of these phenomena. Migration- and/or sorption-related problems with respect to glass, metal, paper-based and polymeric packaging materials are discussed, and their importance is illustrated using published examples. The effects of migrating and absorbed components on food safety, quality, and the environment are presented for various foods and packaging materials. The impact of currently popular packaging techniques such as microwavable, ovenable, and retortable packaging on migration and sorption are discussed with examples. Analytical techniques for investigating migration and sorption phenomena in food packaging are critically reviewed, with special emphasis on the use and characteristics of food-simulating liquids (FSLs). Finally, domestic and international regulations concerning migration in packaged foods, and their impact on food packaging is briefly presented.

  16. Fluid-bed combustion

    Energy Technology Data Exchange (ETDEWEB)

    Hunt, G.; Schoebotham, N.

    1981-02-01

    In Energy Equipment Company's two-stage fluidized bed system, partial combustion in a fluidized bed is followed by burn-off of the generated gases above the bed. The system can be retrofitted to existing boilers, and can burn small, high ash coal efficiently. It has advantages when used as a hot gas generator for process drying. Tests on a boiler at a Cadbury Schweppes plant are reported.

  17. Sorptive Removal of Cesium and Cobalt Ions in a Fixed bed Column Using Lewatit S100 Cation Exchange Resin

    International Nuclear Information System (INIS)

    El-Naggar, M.R.; Ibrahim, H.A.; El-Kamash, A.M.

    2014-01-01

    The sorptive removal of cesium and cobalt ions from aqueous solutions in a fixed bed column packed with Lewatit S100® cation exchange resin has been investigated. A preliminary batch studies were performed to estimate the effect of pH and contact time on the sorption process. Results indicated that Cs + and Co 2+ could be efficiently removed using Lewatit S100® at a ph range of 4-7 with more affinity towards Cs than Co 2+ . Kinetic models have been applied to the sorption rate data and the relevant parameters were determined. The obtained results indicated that the sorption of both Cs + and Co 2+ on Lewatit S100 followed pseudo second-order rather than pseudo first-order or Morris-Webber model. Fixed bed experiments were conducted at a constant initial concentration of 100 mg/l whereas the effect of bed depth (3, 4.5 and 6 cm) and volumetric flow rate (3 and 5 ml/min.) on the breakthrough characteristics of the fixed bed sorption systems were determined. The experimental sorption data were fitted to the well-established column models namely; Thomas and BDST models to compute the different model parameters. The higher column sorption capacities were obtained at bed depth of 3 cm with a flow rate of 3 ml/min., for both Cs + and Co 2+ . The BDST model appeared to describe experimental results better than Thomas model. Results indicate that Lewatit S100® is an efficient material for the removal of cesium and cobalt ions from aqueous solutions.

  18. Fluidised bed combustion system

    International Nuclear Information System (INIS)

    McKenzie, E.C.

    1976-01-01

    Fluidized bed combustion systems that facilitates the maintenance of the depth of the bed are described. A discharge pipe projects upwardly into the bed so that bed material can flow into its upper end and escape downwardly. The end of the pipe is surrounded by an enclosure and air is discharged into the enclosure so that material will enter the pipe from within the enclosure and have been cooled in the enclosure by the air discharged into it. The walls of the enclosure may themselves be cooled

  19. Complex Metal Hydrides for Hydrogen, Thermal and Electrochemical Energy Storage

    DEFF Research Database (Denmark)

    Moller, Kasper T.; Sheppard, Drew; Ravnsbaek, Dorthe B.

    2017-01-01

    Hydrogen has a very diverse chemistry and reacts with most other elements to form compounds, which have fascinating structures, compositions and properties. Complex metal hydrides are a rapidly expanding class of materials, approaching multi-functionality, in particular within the energy storage...... inspiration to solve the great challenge of our time: efficient conversion and large-scale storage of renewable energy....... field. This review illustrates that complex metal hydrides may store hydrogen in the solid state, act as novel battery materials, both as electrolytes and electrode materials, or store solar heat in a more efficient manner as compared to traditional heat storage materials. Furthermore, it is highlighted...

  20. 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

  1. 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

  2. Thermophysical properties of solid lithium hydride and its isotopic modifications

    International Nuclear Information System (INIS)

    Mel'nikova, T.N.

    1981-01-01

    The theory of the anharmonic lattice is used to calculate the thermophysical properties (thermal expansivity, lattice constant, compressibility, and elastic moduli) of all the isotopic modifications of solid lithium hydride sup(6,7)Li(H,D,T) at temperatures up to the melting point. A general analysis of isotopic effects is carried out; in particular the reverse isotopic effect in the lattice constant is explained and the isotopic effect in melting is discussed. The results of the calculations agree with available experimental data and can be used for those isotopic modifications of lithium hydride for which there exist no experimental results. (author)

  3. Influence of sorption competition on sorption data for MX-80 bentonite used in performance assessment

    International Nuclear Information System (INIS)

    Bradbury, M.H.; Baeyens, B.; Marques Fernandes, M.

    2012-01-01

    Document available in extended abstract form only. In order to obtain a (quasi) mechanistic understanding of radionuclide uptake on clay minerals and argillaceous rocks, the majority of sorption experiments have been carried out on purified clay minerals such as montmorillonite and illite at trace concentrations (sorption edges), or as a function of concentration (sorption isotherms), with a single radionuclide under well-defined conditions in simple background electrolytes. As a result of such studies the 2 site proto-lysis non electrostatic surface complexation cation exchange (2SPNE SC/CE) sorption model, was developed and has been successfully applied to quantitatively describe the uptake of numerous radionuclides of differing valences as a function of pH and concentration on montmorillonite. In a deep geological repository for high level waste, stable impurities arise from many sources: they are present in the pore waters, in the tunnel back fill materials and host rock formations, they arise from the corrosion of the carbon steel canister and finally they are dissolved from the spent fuel and vitrified high level waste simultaneously with the radionuclides. These impurities, which are an integral part of a realistic repository system, can potentially compete with radionuclides for the sorption sites on the backfill materials and host rock and thus reduce their uptake on them. The influence of competitive sorption is not intrinsically included (or only partly so) in the sorption model. It is clearly an inherently important issue to quantify the influence of sorption competition on the transport of released radionuclides through the multi-barrier system in a deep repository. In this study an extreme case of a competitive sorption scenario in the near field of a HLW repository is presented. Two factors are considered: one associated with the high concentrations and the other with competitive sorption effects. The tendency in both cases is to cause a reduction in

  4. Radionuclides sorption in clay soils

    International Nuclear Information System (INIS)

    Siraky, G.; Lewis, C.; Hamlat, S.; Nollmann, C.E.

    1987-01-01

    The sorption behaviour of clay soils is examined through a parametric study of the distribution coefficient (Kd) for the radionuclides of interest, Cs and Sr. This work is a preliminary stage of the migration studies of these nuclides in a porous medium (ground of Ezeiza, Argentina) and the evaluation of radiologic impact of the removal of low and intermediate activity wastes in shallow trenches. The determination of Kd is performed by a static technique or batch. The phases are separated by centrifugation at 20000 g during 1 hour. The activity of supernatant solution of Cs-137 and Sr-85 is measured in a detecting system of I Na(Tl) well-type. Two types of parameters were changed: a) those related to the determination method: phase separation (centrifugation vs. centrifugation plus filtration); equilibrium period, ratio solid/liquid; b) those related to the geochemical system: pH of contact solution, carrier concentration, competitive ions, ionic strength, desorption. It was observed that the modification of parameters in the Kd-measurement does not change the order of magnitude of results. (Author)

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

    International Nuclear Information System (INIS)

    Pettersson, Kjell; Oskarsson, Magnus; Bergqvist, Hans

    2003-04-01

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

  6. Neptunium(V) sorption on kaolinite

    Energy Technology Data Exchange (ETDEWEB)

    Amayri, S.; Jermolajev, A.; Reich, T. [Mainz Univ. (Germany). Inst. of Nuclear Chemistry

    2011-07-01

    The sorption behavior of neptunium(V) onto the clay mineral kaolinite was studied in batch experiments under different experimental conditions: [Np(V)] = 7 x 10{sup -12}-8 x 10{sup -6} M, solid-to-liquid ratio 2-20 g L{sup -1}, I = 0.1 and 0.01 M NaClO{sub 4}, pH = 6-10, ambient air and Ar atmosphere. The short-lived isotope {sup 239}Np (T{sub 1/2} = 2.36 d) was used instead of {sup 237}Np (T{sub 1/2} = 2.14 x 10{sup 6} a) to study the sorption behavior of Np(V) at environmentally-relevant concentrations, i.e., 7 x 10{sup -12} M Np. In addition, {sup 239}Np(V) served as tracer to measure sorption isotherms over six orders of magnitude in Np concentration (4.8 x 10{sup -12}-1.0 x 10{sup -4} M). The results show that Np(V) sorption on kaolinite is strongly influenced by pH, CO{sub 2}, and ionic strength. The sorption of 8 x 10{sup -6} M Np(V) at pH 9.0, and ionic strength of 0.1 M NaClO{sub 4} was proportional to the solid-to-liquid ratio of kaolinite in the range of 2-10 g L{sup -1}. In the absence of CO{sub 2}, the Np(V) uptake increased continuously with increasing pH value up to 97% at pH 10. Under ambient CO{sub 2}, the sorption of Np decreased above pH 8 up to zero at pH 10. An increase of Np(V) concentration from 7 x 10{sup -12} to 8 x 10{sup -6} M resulted in a shift of the sorption pH edge by up to one pH unit to higher pH values. The ionic strength influenced the Np(V) sorption onto kaolinite only in the presence of ambient CO{sub 2}. Under Ar atmosphere the sorption of Np(V) was independent from ionic strength, indicating the formation of inner-sphere complexes of Np(V) with kaolinite. Time-dependent batch experiments at pH 9.0 under ambient CO{sub 2} showed that the sorption of Np(V) on kaolinite is fast and fully reversible over six orders in Np(V) concentration. (orig.)

  7. Sorption behavior of neptunium on bentonite -- Effect of calcium ion on the sorption

    International Nuclear Information System (INIS)

    Kozai, Naofumi; Ohnuki, Toshihiko; Muraoka, Susumu

    1995-01-01

    The sorption behavior of neptunium on bentonite was studied with batch type sorption and desorption experiments over a pH range of 2 to 8. A series of parallel studies using Na-smectite, Ca-smectite and admixtures of Na-smectite and calcite quantified the capacity of Ca 2+ (which occurs in bentonite as an exchangeable cation of smectite and as a component of calcite) to inhibit the sorption of neptunium. The distribution coefficient (K d ) of neptunium for bentonite was constant from pH 2 to 7, while for pure Na-smectite K d increased below pH 5 due to specific sorption of neptunium on Na-smectite. Specific sorption was defined as occurring when neptunium could be desorbed by a strong acid (1 M HCl) but was stable in the presence of 1 M KCl. It was found that the quantity of neptunium sorbed on Na-smectite was inversely proportional to the concentration of Ca 2+ in solution, an effect most pronounced at pH 2+ limits the specific sorption capacity of Na-smectite for neptunium. Similarly, in the mixture of Na-smectite and calcite, sufficient Ca 2+ was solubilized to depress neptunium sorption. This investigation demonstrates that Ca 2+ contained in bentonite as exchangeable cation and released from calcite reduces the specific sorption of neptunium

  8. A comparison of the smeared-dislocation and super-dislocation description of a hydrided region in the context of modelling delayed hydride cracking initiation

    International Nuclear Information System (INIS)

    Smith, E.

    1994-01-01

    In quantifying the stress distribution within a hydrided region in the context of modelling delayed hydride cracking (DHC) initiation in zirconium alloys, this paper highlights the desirability of accounting for image effects, i.e. the interaction between the hydrided region and any free surface, for example a sharp crack, blunt notch or planar surface. The super-dislocation representation of a finite thickness hydrided region is ideal for accounting for image effects. It also adequately accounts for the finite thickness, t, of a hydrided region provided, as is the case in practice, we are concerned with the stress value within the hydride at distances ≥ 0.25 t from an end of the region. (Author)

  9. Effects of sorption behaviour on contaminant migration

    International Nuclear Information System (INIS)

    Melnyk, T.W.

    1985-11-01

    The effects of sorption behaviour on contaminant migration in groundwater systems are varied. Retardation of migration and dispersive effects can vary widely and contaminant concentration profiles can take a number of different shapes. This report examines the nature of some of these effects, especially those due to sorption behaviours that are dependent on the concentration of the contaminant in the groundwater. The effects are calculated using, in most cases, analytical solutions to the chemical equations imbedded in a simple reaction-cell or box-model transport algorithm. The hydrogeological parameters are held constant, and radioactive decay and hydrodynamic dispersion are excluded. A general discussion of the role of sorption equations in transport modelling is followed by presentation of migration results for a number of models of sorption behaviour varying from linear isotherms, Langmuir, Freundlich and ion-exchange isotherms, to precipitation reactions and multiple-site sorption reactions. The results are compared and general conclusions are drawn about the various migration behaviours calculated. The conclusions are that equilibrium sorption of trace contaminants can be modelled with linear isotherms (constant distribution coefficients or constant retardation factors) but the evaluation and extrapolation of the distribution coefficient are not easy. Nonlinear isotherms lead to unsymmetrical migration fronts. A comparison of Freundlich and linear isotherms is made. Sorption/desorption kinetic factors can be significant on the time scale of laboratory experiments and can cause large dispersive effects. Slow but important reactions can be missed altogether. Precipitation or mineralization behaviour cannot be modelled with constant distribution coefficients. Also, mineralization reactions can be kinetically slow even on the geological time scale. 89 refs

  10. Technetium sorption by stibnite from natural water

    International Nuclear Information System (INIS)

    Peretroukhine, V.; Sergeant, C.; Deves, G.; Poulain, S.; Vesvres, M.H.; Thomas, B.; Simonoff, M.

    2006-01-01

    The sorption of technetium by powdered and polished mineral stibnite Sb 2 S 3 has been investigated in simulated and natural underground waters from the Meuse/Haute-Marne region (France). The sorption by powdered stibnite has been found to be complete under both aerobic and anaerobic conditions in batch experiments. The sorption rate is higher in the absence of oxygen than under aerobic condition. Increasing the temperature from 30 C to 60 C results in a rise of the sorption rate by 9.1 and 27 times under anaerobic and aerobic conditions, respectively. The observed differences in sorption kinetics in the presence and in absence of oxygen are explained by the interaction of oxygen with sulfide ion in aerobic conditions and by the reduction of technetium(VII) by iron(II) and by other impurities present in natural water and in the mineral, and by the subsequent sorption of Tc(IV) on stibnite under anaerobic conditions. The sorption on a polished mineral surface resulted in the formation of a technetium film, probably Tc 2 S 7 , with a thickness of 1-3 μg Tc/cm 2 pH 3-6 and 4-12 μg Tc/cm 2 at 9-12. The simultaneous formation of stibnite colloids with adsorbed technetium occurs at pH 9-12. The study of the technetium film on the mineral by proton induced X-ray emission analysis showed it to be at least one order of magnitude thinner on the SiO 2 impurities than on the main Sb 2 S 3 component and the iron impurities. (orig.)

  11. Computer simulation of molecular sorption in zeolites

    International Nuclear Information System (INIS)

    Calmiano, Mark Daniel

    2001-01-01

    The work presented in this thesis encompasses the computer simulation of molecular sorption. In Chapter 1 we outline the aims and objectives of this work. Chapter 2 follows in which an introduction to sorption in zeolites is presented, with discussion of structure and properties of the main zeolites studied. Chapter 2 concludes with a description of the principles and theories of adsorption. In Chapter 3 we describe the methodology behind the work carried out in this thesis. In Chapter 4 we present our first computational study, that of the sorption of krypton in silicalite. We describe work carried out to investigate low energy sorption sites of krypton in silicalite where we observe krypton to preferentially sorb into straight and sinusoidal channels over channel intersections. We simulate single step type I adsorption isotherms and use molecular dynamics to study the diffusion of krypton and obtain division coefficients and the activation energy. We compare our results to previous experimental and computational studies where we show our work to be in good agreement. In Chapter 5 we present a systematic study of the sorption of oxygen and nitrogen in five lithium substituted zeolites using a transferable interatomic potential that we have developed from ab initio calculations. We show increased loading of nitrogen compared to oxygen in all five zeolites studied as expected and simulate adsorption isotherms, which we compare to experimental and simulated data in the literature. In Chapter 6 we present work on the sorption of ferrocene in the zeolite NaY. We show that a simulated, low energy sorption site for ferrocene is correctly located by comparing to X-ray powder diffraction results for this same system. The thesis concludes with some overall conclusions and discussion of opportunities for future work. (author)

  12. Hydrogen storage properties of carbon nanomaterials and carbon containing metal hydrides

    Energy Technology Data Exchange (ETDEWEB)

    Maehlen, Jan Petter

    2003-07-01

    The topic of this thesis is structural investigations of carbon containing materials in respect to their hydrogen storage properties. This work was initially triggered by reports of extremely high hydrogen storage capacities of specific carbon nanostructures. It was decided to try to verify and understand the mechanisms in play in case of the existence of such high hydrogen densities in carbon. Two different routes towards the goal were employed; by studying selected hydrides with carbon as one of its constituents (mainly employing powder diffraction techniques in combination with hydrogen absorption and desorption measurements) and by carefully conducting hydrogen sorption experiments on what was believed to be the most ''promising'' carbon nanomaterial sample. In the latter case, a lot of effort was attributed to characterisations of different carbon nanomaterial containing samples with the aid of electron microscopy. Three different carbon-containing metal hydride systems, Y2C-H, YCoC-H and Y5SiC0.2-H, were examined. A relation between hydrogen occupation and the local arrangement of metal and carbon atoms surrounding the hydrogen sites was established. Several characteristic features of the compounds were noted in addition to solving the structure of the former unknown deuterideY5Si3C0.2D2.0 by the use of direct methods. Several carbon-nanomaterial containing samples were studied by means of transmission electron microscopy and powder diffraction, thus gaining knowledge concerning the structural aspects of nanomaterials. Based on these investigations, a specific sample containing a large amount of open-ended single-wall carbon nanotubes was chosen for subsequent hydrogen storage experiments. The latter experiments revealed moderate hydrogen storage capacities of the nanotubes not exceeding the values obtained for more conventional forms of carbon. These two different routes in investigating the hydrogen storage properties of carbon and carbon containing alloys

  13. Hydrogen storage properties of carbon nanomaterials and carbon containing metal hydrides

    Energy Technology Data Exchange (ETDEWEB)

    Maehlen, Jan Petter

    2003-07-01

    The topic of this thesis is structural investigations of carbon containing materials in respect to their hydrogen storage properties. This work was initially triggered by reports of extremely high hydrogen storage capacities of specific carbon nanostructures. It was decided to try to verify and understand the mechanisms in play in case of the existence of such high hydrogen densities in carbon. Two different routes towards the goal were employed; by studying selected hydrides with carbon as one of its constituents (mainly employing powder diffraction techniques in combination with hydrogen absorption and desorption measurements) and by carefully conducting hydrogen sorption experiments on what was believed to be the most ''promising'' carbon nanomaterial sample. In the latter case, a lot of effort was attributed to characterisations of different carbon nanomaterial containing samples with the aid of electron microscopy. Three different carbon-containing metal hydride systems, Y2C-H, YCoC-H and Y5SiC0.2-H, were examined. A relation between hydrogen occupation and the local arrangement of metal and carbon atoms surrounding the hydrogen sites was established. Several characteristic features of the compounds were noted in addition to solving the structure of the former unknown deuterideY5Si3C0.2D2.0 by the use of direct methods. Several carbon-nanomaterial containing samples were studied by means of transmission electron microscopy and powder diffraction, thus gaining knowledge concerning the structural aspects of nanomaterials. Based on these investigations, a specific sample containing a large amount of open-ended single-wall carbon nanotubes was chosen for subsequent hydrogen storage experiments. The latter experiments revealed moderate hydrogen storage capacities of the nanotubes not exceeding the values obtained for more conventional forms of carbon. These two different routes in investigating the hydrogen storage properties of carbon and

  14. Fluidized bed incinerator development

    International Nuclear Information System (INIS)

    Ziegler, D.L.; Johnson, A.J.

    1976-01-01

    A fluidized bed incinerator is being developed for burning rad contaminated solid and liquid waste materials. In situ neutralization of acid gases by the bed material, catalytic afterburning, and gas filtration are used to produce a clean flue gas without the use of aqueous scrubbing

  15. Characteristics of hydride precipitation and reorientation in spent-fuel cladding

    International Nuclear Information System (INIS)

    Chung, H.M.; Daum, R.S.; Hiller, J.M.; Billone, M.C.

    2002-01-01

    Transmission electron microscopy (TEM) was used to examine Zircaloy fuel cladding, either discharged from several PWRs and a BWR after irradiation to fluence levels of 3.3 to 8.6 X 10 21 n cm -2 (E > 1 MeV) or hydrogen-charged and heat-treated under stress to produce radial hydrides; the goal was to determine the microstructural and crystallographic characteristics of hydride precipitation. Morphologies, distributions, and habit planes of various types of hydrides were determined by stereo-TEM. In addition to the normal macroscopic hydrides commonly observed by optical microscopy, small 'microscopic' hydrides are present in spent-fuel cladding in number densities at least a few orders of magnitude greater than that of macroscopic hydrides. The microscopic hydrides, observed to be stable at least up to 333 deg C, precipitate in association with -type dislocations. While the habit plane of macroscopic tangential hydrides in the spent-fuel cladding is essentially the same as that of unirradiated unstressed Zircaloys, i.e., the [107] Zr plane, the habit plane of tangential hydrides that precipitate under high tangential stress is the [104] Zr plane. The habit plane of radial hydrides that precipitate under tangential stress is the [011] Zr pyramidal plane, a naturally preferred plane for a cladding that has 30 basal-pole texture. Effects of texture on the habit plane and the threshold stress for hydride reorientation are also discussed. (authors)

  16. In situ synchrotron X-ray diffraction study of hydrides in Zircaloy-4 during thermomechanical cycling

    Energy Technology Data Exchange (ETDEWEB)

    Cinbiz, Mahmut N., E-mail: cinbizmn@ornl.gov [Department of Mechanical and Nuclear Engineering, Pennsylvania State University, University Park, PA, 16802 (United States); Koss, Donald A., E-mail: koss@ems.psu.edu [Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA, 16802 (United States); Motta, Arthur T., E-mail: atm2@psu.edu [Department of Mechanical and Nuclear Engineering, Pennsylvania State University, University Park, PA, 16802 (United States); Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA, 16802 (United States); Park, Jun-Sang, E-mail: parkjs@aps.anl.gov [Advanced Photon Source, Argonne National Laboratory, Argonne, IL, 60439 (United States); Almer, Jonathan D., E-mail: almer@aps.anl.gov [Advanced Photon Source, Argonne National Laboratory, Argonne, IL, 60439 (United States)

    2017-04-15

    The d-spacing evolution of both in-plane and out-of-plane hydrides has been studied using in situ synchrotron radiation X-ray diffraction during thermo-mechanical cycling of cold-worked stress-relieved Zircaloy-4. The structure of the hydride precipitates is such that the δ{111} d-spacing of the planes aligned with the hydride platelet face is greater than the d-spacing of the 111 planes aligned with the platelet edges. Upon heating from room temperature, the δ{111} planes aligned with hydride plate edges exhibit bi-linear thermally-induced expansion. In contrast, the d-spacing of the (111) plane aligned with the hydride plate face initially contracts upon heating. These experimental results can be understood in terms of a reversal of stress state associated with precipitating or dissolving hydride platelets within the α-zirconium matrix. - Highlights: •The δ{111} d-spacings aligned with the hydride plate edges exhibit a bi-linear thermal expansion. •Stress state reversal is predicted with the onset of hydride dissolution. •During dissolution, the δ{111} planes oriented parallel to the hydride plate face initially contract upon heating. •Hydride d-spacings indicate that both in-plane (circumferential) and out-of-plane (radial) hydrides are in the same strain-state and likely in the same stress state as well.

  17. Quantifying the stress fields due to a delta-hydride precipitate in alpha-Zr matrix

    Energy Technology Data Exchange (ETDEWEB)

    Tummala, Hareesh [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Capolungo, Laurent [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Tome, Carlos N. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-10-19

    This report is a preliminary study on δ-hydride precipitate in zirconium alloy performed using 3D discrete dislocation dynamics simulations. The ability of dislocations in modifying the largely anisotropic stress fields developed by the hydride particle in a matrix phase is addressed for a specific dimension of the hydride. The influential role of probable dislocation nucleation at the hydride-matrix interface is reported. Dislocation nucleation around a hydride was found to decrease the shear stress (S13) and also increase the normal stresses inside the hydride. We derive conclusions on the formation of stacks of hydrides in zirconium alloys. The contribution of mechanical fields due to dislocations was found to have a non-negligible effect on such process.

  18. The influence of hydride on fracture toughness of recrystallized Zircaloy-4 cladding

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, Hsiao-Hung, E-mail: 175877@mail.csc.com.tw [Institute of Nuclear Energy Research (INER), Lungtan Township, Taoyuan County 32546, Taiwan, ROC (China); China Steel Corporation, Hsiao Kang District, Kaohsiung 81233, Taiwan, ROC (China); Chiang, Ming-Feng [China Steel Corporation, Hsiao Kang District, Kaohsiung 81233, Taiwan, ROC (China); Chen, Yen-Chen [Institute of Nuclear Energy Research (INER), Lungtan Township, Taoyuan County 32546, Taiwan, ROC (China)

    2014-04-01

    In this work, RXA cladding tubes were hydrogen-charged to target hydrogen content levels between 150 and 800 wppm (part per million by weight). The strings of zirconium hydrides observed in the cross sections are mostly oriented in the circumferential direction. The fracture toughness of hydrided RXA Zircaloy-4 cladding was measured to evaluate its hydride embrittlement susceptibility. With increasing hydrogen content, the fracture toughness of hydrided RXA cladding decreases at both 25 °C and 300 °C. Moreover, highly localized hydrides (forming a hydride rim) aggravate the degradation of the fracture properties of RXA Zircaloy-4 cladding at both 25 °C and 300 °C. Brittle features in the form of quasi-cleavages and secondary cracks were observed on the fracture surface of the hydride rim, even for RXA cladding tested at 300 °C.

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

    International Nuclear Information System (INIS)

    Peretti, H.A.; Corso, H.L.; Gonzalez, O.A.; Fernandez, L.; Ghilarducci, A.A.; Salva, H.R.

    1999-01-01

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

  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. A system of hydrogen powered vehicles with liquid organic hydrides

    International Nuclear Information System (INIS)

    Taube, M.

    1981-07-01

    A motor car system based on the hydrogen produced by nuclear power stations during the night in the summer, and coupled with organic liquid hydride seems to be a feasible system in the near future. Such a system is discussed and the cost is compared with gasoline. (Auth.)

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

    Science.gov (United States)

    Congdon, James W [Aiken, SC

    2009-03-17

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

  3. Hydrogen storage alloys for nickel/metal hydride battery

    Energy Technology Data Exchange (ETDEWEB)

    Kuriyama, Nobuhiro; Sakai, Tetsuo; Myamura, Hiroshi; Tanaka, Hideaki; Ishikawa, Hiroshi; Uehara, Itsuki [Osaka National Research Inst. (Japan)

    1996-06-01

    Efforts to improve performance of metal hydride electrodes such as substitution of alloy components, heat treatment, and surface treatment intended to change surface and bulk structure of hydrogen storage alloys, mainly LaNi{sub 5} based alloys, are reviewed. The importance of control of morphology is emphasized. (author)

  4. Cascades for hydrogen isotope separation using metal hydrides

    International Nuclear Information System (INIS)

    Hill, F.B.; Grzetic, V.

    1982-01-01

    Designs are presented for continuous countercurrent hydrogen isotope separation cascades based on the use of metal hydrides. The cascades are made up of pressure swing adsorption (PSA) or temperature swing adsorption (TSA) stages. The designs were evolved from consideration of previously conducted studies of the separation performance of four types of PSA and TSA processes

  5. Deiodination reactions using tributyltin hydride for potential labelling experiments

    International Nuclear Information System (INIS)

    Zippi, E.M.; Plourde, G.W. II; Satyamurthy, N.

    1995-01-01

    2,6-Dinitro-1-iodobenzene and 2,4-dinitro-1-iodobenzene were deiodinated with tributylin hydride at different temperatures using various addition modes. The product ratios of 1,3-dinitrobenzene and the corresponding tributylstannyldinitrobenzene compounds were determined by NMR in order to evaluate the optimum conditions for impending tritiation experiments. (Author)

  6. Modeling of electrochemical hydrogen storage in metal hydride electrodes

    NARCIS (Netherlands)

    Ledovskikh, A.; Danilov, D.; Vermeulen, P.; Notten, P.H.L.

    2010-01-01

    The recently presented Electrochemical Kinetic Model (EKM), describing the electrochemical hydrogen storage in hydride-forming materials, has been extended by the description of the solid/electrolyte interface, i.e. the charge transfer kinetics and electrical double layer charging. A complete set of

  7. Modeling of electrochemical hydrogen storage in metal hydride electrodes

    NARCIS (Netherlands)

    Ledovskikh, A.; Danilov, D.; Vermeulen, P.; Notten, P.H.L.

    2010-01-01

    The recently presented electrochemical kinetic model, describing the electrochemical hydrogen storage in hydride-forming materials, was extended by the description of the solid/electrolyte interface, i.e., the charge-transfer kinetics and electrical double-layer charging. A complete set of equations

  8. Metal Hydride assited contamination on Ru/Si surfaces

    NARCIS (Netherlands)

    Pachecka, Malgorzata; Lee, Christopher James; Sturm, Jacobus Marinus; Bijkerk, Frederik

    2013-01-01

    In extreme ultraviolet lithography (EUVL) residual tin, in the form of particles, ions, and atoms, can be deposited on nearby EUV optics. During the EUV pulse, a reactive hydrogen plasma is formed, which may be able to react with metal contaminants, creating volatile and unstable metal hydrides that

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

    International Nuclear Information System (INIS)

    Botzung, M.

    2008-01-01

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

  10. Diastereoselectivity in the reduction of bicyclic enones with hindered hydrides

    OpenAIRE

    Camozzato, Andreza C.; Tenius, Beatriz S. M.; Oliveira, Eduardo R. de; Viegas Jr., Cláudio; Victor, Maurício M.; Silveira, Leandro G. da

    2008-01-01

    Reduction of five substituted octalones employing lithium tri-sec-butylborohydride (L-selectride®) in THF and ethyl ether led to allylic alcohols with moderate diastereoselectivity. The stereoselectivity of addition of bulky hydrides showed to be different from most examples in the literature and was strongly influenced by substitution on the octalone ring.

  11. Diastereoselectivity in the reduction of bicyclic enones with hindered hydrides

    International Nuclear Information System (INIS)

    Camozzato, Andreza C.; Tenius, Beatriz S. M.; Oliveira, Eduardo R. de; Viegas Junior, Claudio; Victor, Mauricio M.; Silveira, Leandro G. da

    2008-01-01

    Reduction of five substituted octalones employing lithium tri-sec-butylborohydride (L-selectride R ) in THF and ethyl ether led to allylic alcohols with moderate diastereoselectivity. The stereoselectivity of addition of bulky hydrides showed to be different from most examples in the literature and was strongly influenced by substitution on the octalone ring. (author)

  12. Fractal analysis of electrolytically-deposited palladium hydride dendrites

    International Nuclear Information System (INIS)

    Bursill, L.A.; Julin, Peng; Xudong, Fan.

    1990-01-01

    The fractal scaling characteristics of the surface profile of electrolytically-deposited palladium hydride dendritic structures have been obtained using conventional and high resolution transmission electron microscopy. The results are in remarkable agreement with the modified diffusion-limited aggregation model. 19 refs., 3 tabs., 13 figs

  13. Development of transmutation technologies of radioactive waste by actinoid hydride

    International Nuclear Information System (INIS)

    Konashi, Kenji; Matsui, Hideki; Yamawaki, Michio

    2001-01-01

    Two waste treatment methods, geological disposal and transmutation, have been studied. The transmutation method changes long-lived radioactive nuclides to short-lived one or stabilizes them by nuclear transformation. The transmutation by actinoid hydride is exactly alike that transformation method from actinoid disposal waste to Pu fuel. For this object, OMEGA project is processing now. The transmutation is difficult by two causes such as large amount of long-lived radioactive nuclides and not enough development of control technologies of nuclear reaction except atomic reactor. The transmutation using actinoid hydride has merits that the amount of actinoid charged in the target increases and the effect of thermal neutrons on fuel decreases depending on homogeneous transmutation velocity in the target. Development of stable actinoid hydride under the conditions of reactor temperature and irradiation environment is important. The experimental results of U-ZrH 1.6 are shown in this paper. The irradiation experiment using Th hydride has been proceeding. (S.Y.)

  14. Hydrogen and dihydrogen bonding of transition metal hydrides

    International Nuclear Information System (INIS)

    Jacobsen, Heiko

    2008-01-01

    Intermolecular interactions between a prototypical transition metal hydride WH(CO) 2 NO(PH 3 ) 2 and a small proton donor H 2 O have been studied using DFT methodology. The hydride, nitrosyl and carbonyl ligand have been considered as site of protonation. Further, DFT-D calculations in which empirical corrections for the dispersion energy are included, have been carried out. A variety of pure and hybrid density functionals (BP86, PW91, PBE, BLYP, OLYP, B3LYP, B1PW91, PBE0, X3LYP) have been considered, and our calculations indicate the PBE functional and its hybrid variation are well suited for the calculation of transition metal hydride hydrogen and dihydrogen bonding. Dispersive interactions make up for a sizeable portion of the intermolecular interaction, and amount to 20-30% of the bond energy and to 30-40% of the bond enthalpy. An energy decomposition analysis reveals that the H...H bond of transition metal hydrides contains both covalent and electrostatic contributions

  15. Hydrogen and dihydrogen bonding of transition metal hydrides

    Science.gov (United States)

    Jacobsen, Heiko

    2008-04-01

    Intermolecular interactions between a prototypical transition metal hydride WH(CO) 2NO(PH 3) 2 and a small proton donor H 2O have been studied using DFT methodology. The hydride, nitrosyl and carbonyl ligand have been considered as site of protonation. Further, DFT-D calculations in which empirical corrections for the dispersion energy are included, have been carried out. A variety of pure and hybrid density functionals (BP86, PW91, PBE, BLYP, OLYP, B3LYP, B1PW91, PBE0, X3LYP) have been considered, and our calculations indicate the PBE functional and its hybrid variation are well suited for the calculation of transition metal hydride hydrogen and dihydrogen bonding. Dispersive interactions make up for a sizeable portion of the intermolecular interaction, and amount to 20-30% of the bond energy and to 30-40% of the bond enthalpy. An energy decomposition analysis reveals that the H⋯H bond of transition metal hydrides contains both covalent and electrostatic contributions.

  16. Hydrogen and dihydrogen bonding of transition metal hydrides

    Energy Technology Data Exchange (ETDEWEB)

    Jacobsen, Heiko [KemKom, Libellenweg 2, 25917 Leck, Nordfriesland (Germany)], E-mail: jacobsen@kemkom.com

    2008-04-03

    Intermolecular interactions between a prototypical transition metal hydride WH(CO){sub 2}NO(PH{sub 3}){sub 2} and a small proton donor H{sub 2}O have been studied using DFT methodology. The hydride, nitrosyl and carbonyl ligand have been considered as site of protonation. Further, DFT-D calculations in which empirical corrections for the dispersion energy are included, have been carried out. A variety of pure and hybrid density functionals (BP86, PW91, PBE, BLYP, OLYP, B3LYP, B1PW91, PBE0, X3LYP) have been considered, and our calculations indicate the PBE functional and its hybrid variation are well suited for the calculation of transition metal hydride hydrogen and dihydrogen bonding. Dispersive interactions make up for a sizeable portion of the intermolecular interaction, and amount to 20-30% of the bond energy and to 30-40% of the bond enthalpy. An energy decomposition analysis reveals that the H...H bond of transition metal hydrides contains both covalent and electrostatic contributions.

  17. Cascades for hydrogen isotope separation using metal hydrides

    Energy Technology Data Exchange (ETDEWEB)

    Hill, F B; Grzetic, V [Brookhaven National Lab., Upton, NY (USA)

    1983-02-01

    Designs are presented for continuous countercurrent hydrogen isotope separation cascades based on the use of metal hydrides. The cascades are made up of pressure swing adsorption (PSA) or temperature swing adsorption (TSA) stages. The designs were evolved from consideration of previously conducted studies of the separation performance of four types of PSA and TSA processes.

  18. Diffusion model of delayed hydride cracking in zirconium alloys

    NARCIS (Netherlands)

    Shmakov, AA; Kalin, BA; Matvienko, YG; Singh, RN; De, PK

    2004-01-01

    We develop a method for the evaluation of the rate of delayed hydride cracking in zirconium alloys. The model is based on the stationary solution of the phenomenological diffusion equation and the detailed analysis of the distribution of hydrostatic stresses in the plane of a sharp tensile crack.

  19. Hydrogen Storage in Porous Materials and Magnesium Hydrides

    NARCIS (Netherlands)

    Grzech, A.

    2013-01-01

    In this thesis representatives of two different types of materials for potential hydrogen storage application are presented. Usage of either nanoporous materials or metal hydrides has both operational advantages and disadvantages. A main objective of this thesis is to characterize the hydrogen

  20. The Properties of Some Simple Covalent Hydrides: An Ab Initio ...

    African Journals Online (AJOL)

    Some properties of the monomeric binary hydrides of the elements of the first two rows of the periodic table have been determined using ab initio molecular orbital theory. The properties in question are the energetic, structural, electronic, topological and vibrational characteristics. In general, a gradual convergence towards ...

  1. Synthesis, properties, and assimilation methods of aluminium hydride

    International Nuclear Information System (INIS)

    Mirsaidov, U.M.

    2013-01-01

    We have discovered a new source of aluminium hydride-conversion of tetrahydrofurane under influence of halogenous alkyls. We have proposed the chlorbenzene method of synthesis of AlH 3 , which excludes adhesion and ensure high quality of the product with respect to its purity, thermal stability, habits of crystals (round shape), and granulometric composition. We determined capability of benzyl chloride to fix AlH 4 -groups by the way of complexes formation. This allows increasing efficient concentration of AlH 3 solutions and their productivity. We have carried out 'direct' crystallization of aluminium hydride in one stage using interaction of binary metal hydride with aluminium chloride in the medium of ether-toluene at 60-100 d ig C a nd using solvent distillation. In the reaction of Li H with AlCl 3 , we achieved output of pure crystal AlH 3 of hexagonal modification, which was close to quantitative. We have discovered the assimilation methods of aluminium hydride in carrying out of solid-phase chemical reactions. (author)

  2. Sorption of cesium in intact rock

    International Nuclear Information System (INIS)

    Puukko, E.

    2014-04-01

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

  3. Recent progress in sorption mechanisms and models

    International Nuclear Information System (INIS)

    Fedoroff, M.; Lefevre, G.

    2005-01-01

    Full text of publication follows: Sorption-desorption phenomena play an important role in the migration of radioactive species in surface and underground waters. In order to predict the transport of these species, we need a good knowledge of sorption processes and data, together with reliable models able to be included in transport calculation. Traditional approaches based on experimentally determined distribution coefficients (Kd) and sorption isotherms have a limited predictive capability, since they are very sensitive to the numerous parameters characterizing the solution and the solid. Models based on thermodynamic equilibria were developed to account for the influence these parameters: the ion exchange model and the surface complexation models (2-pK mono-site, 1-pK multi-site, with several different electrostatic models: CCM, DLM, BSM, TLM,...). Although these models are very useful, studies performed in recent years showed that they have important theoretical and experimental limitations, which result in the fact that we must be very careful when we use them for extrapolating sorption data to long term and to large natural systems. Among all problems which can be found are: the possibility to fit a set of experimental data with different models, sometimes bad adequacy with the real sorption processes, some theoretical limitations such as a rigorous definition of reference and standard states in surface equilibria, slow kinetics which prevent from equilibrium achievement, irreversibility, solubility and evolution of solid phases... Through the increase of the number of sensitive spectroscopic methods, we are now able to know more about sorption processes at the atomic scale. Models such as the 1-pK CD-MUSIC model can account for the influence of orientation of the faces of the solid. More and more examples of the influence of this orientation on the sorption properties are known. Calculations performed by 'ab initio' modeling is also useful to predict the

  4. The NEA sorption data base (SDB)

    International Nuclear Information System (INIS)

    Ruegger, B.; Ticknor, K.

    1992-01-01

    The current NEA Sorption Data Base is developed to replace the former International Sorption Information Retrieval System (ISIRS) initiated at Pacific Northwest Laboratory and contains about 11,000 distribution coefficients with corresponding experimental condition parameters describing sorption of key nuclides for a large variety of solid and liquid phases. The SDB is designed to run on a micro-computer using the commercially available database software dBASE III Plus. For each recorded sorption experiment, the SDB provides a bibliographical reference, the most complete characterization of the solid and liquid phases available, a description of the experimental conditions and the distribution coefficient or retardation factor for each element studied. When available, parameters such as temperature, initial radionuclide concentration, pH, Eh, contact time, solid to solution ratio, sample origin, oxidation state and type of solution are included. The SDB provides information for a wide variety of rocks or geological materials, buffer backfill candidates, concretes/cements, elements (Am, Cs, Co, I, Np, Pu, Ra, Sr, Se, Tc, U and, to a lesser extent, Ag, Ba, C, Ce, Eu, Fe, Mn, Mo, Na, Nb, Ni, Pd, Pm, Ru, Sb, Sn, Y, Zn, and Zr), or radioisotopes. A compilation of sorption data like SDB provide a readily available source of data for radioactive waste repository performance assessments when site specific data are not available or essential, for example, during a site selection phase. 2 appendices

  5. Radionuclide sorption from the safety evaluation perspective

    International Nuclear Information System (INIS)

    1992-01-01

    Research and development directed towards the assessment of the long-term performance of radioactive waste disposal systems has been recognised as a priority area with a strong need for international co-operation and co-ordination. The ultimate aims is to promote the quality and credibility of safety assessment techniques for radioactive waste disposal. Sorption in the geosphere is one of the key processes for retarding the transport of radionuclide from the underground disposal facility to the biosphere. In many cases, sorption in the near field and in the biosphere is also important. A workshop, organised to favor discussion around a small number of invited papers, was held in October 1991: - to evaluate critically the way sorption processes are incorporated in performance assessment models; - to identify open issues of high priority, and; - to propose future activities to resolve these issues. These proceedings reproduce the invited papers and the conclusions and recommendations adopted by the workshop. Eight papers are in the INIS SCOPE. The main subjects studied are: sorption database comparison, sorption database development and three case studies, experimental techniques, adsorption models

  6. Sorption of radionuclides by tertiary clays

    International Nuclear Information System (INIS)

    Wagner, J.F.; Czurda, K.A.

    1990-01-01

    The sorption capacity of different clay types for some metals (Co, Cs, Sr and Zn), occurring as common radionuclides in radioactive waste deposits, had been analysed by a static (batch technique) and a dynamic method (percolation tests, in which the driving force is a hydraulic gradient). Sorption capacity generally increased with an increasing pH of solution. A decrease of sorption capacity had been observed in the order Zn > Cs ≥ Co > Sr for the batch and Cs > Zn > Sr > Co for the percolation tests. Clay marls showed a distinctly higher sorption respectively retention capacity as pure clays. Sorption capacity depends on solution parameters like type and concentration of radionuclide, pH, salt concentration, etc., and on rock parameters like mineral content (e.g. swelling clay minerals and carbonates), organic material, rock pH, micro fabric, etc. A third parameter of great influence is the contact time between clay and solution. The adsorption isotherms reflect two different adsorption mechanisms: a very rapid adsorption (a few minutes) on the external surfaces of clay minerals and a slow adsorption process (weeks and longer), due to the diffusion of metal ions into the interlayer space of clay minerals. 12 refs., 9 figs., 1 tab

  7. Moisture sorption of Thai red curry powder

    Directory of Open Access Journals (Sweden)

    Sudathip Inchuen

    2009-12-01

    Full Text Available Moisture sorption study was conducted on Thai red curry powder prepared by two different drying methods, viz. microwave and hot-air drying. Moisture sorption isotherms of the red curry powder at 30 C and water activity in the range of 0.113-0.970 were determined by a static gravimetric method. The isotherms exhibited Type III behaviour. The moisture sorption data were fitted to several sorption models and a non-linear regression analysis method was used to evaluate the constants of the sorption equations. The fit was evaluated using the coefficient of determination (R2, the reduced chi-square (2 and the root mean square error (RMSE. The GAB model followed by the Lewiski-3 model gave the best fit to the experimental data. The monolayer moisture content, taken as the safe minimum moisture level in the red curry powder, was determined using the BET equation and was found to range between 0.080 - 0.085 gram water per gram dry matter.

  8. Activation and discharge kinetics of metal hydride electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Johnsen, Stein Egil

    2003-07-01

    Potential step chronoamperometry and Electrochemical Impedance Spectroscopy (eis) measurements were performed on single metal hydride particles. For the {alpha}-phase, the bulk diffusion coefficient and the absorption/adsorption rate parameters were determined. Materials produced by atomisation, melt spinning and conventional casting were investigated. The melt spun and conventional cast materials were identical and the atomised material similar in composition. The particles from the cast and the melt spun material were shaped like parallelepipeds. A corresponding equation, for this geometry, for diffusion coupled to an absorption/adsorption reaction was developed. It was found that materials produced by melt spinning exhibited lower bulk diffusion (1.7E-14 m2/s) and absorption/adsorption reaction rate (1.0E-8 m/s), compared to materials produced by conventionally casting (1.1E-13 m2/s and 5.5E-8 m/s respectively). In addition, the influence of particle active surface and relative diffusion length were discussed. It was concluded that there are uncertainties connected to these properties, which may explain the large distribution in the kinetic parameters measured on metal hydride particles. Activation of metal hydride forming materials has been studied and an activation procedure, for porous electrodes, was investigated. Cathodic polarisation of the electrode during a hot alkaline surface treatment gave the maximum discharge capacity on the first discharge of the electrode. The studied materials were produced by gas atomisation and the spherical shape was retained during the activation. Both an AB{sub 5} and an AB{sub 2} alloy was successfully activated and discharge rate properties determined. The AB{sub 2} material showed a higher maximum discharge capacity, but poor rate properties, compared to the AB{sub 5} material. Reduction of surface oxides, and at the same time protection against corrosion of active metallic nickel, can explain the satisfying results of

  9. Hydrogen sorption properties of the Lasub(1-x)Casub(x)Ni5 and La(Nisub(1-x)Cusub(x))5 systems

    International Nuclear Information System (INIS)

    Shinar, J.; Shaltiel, D.; Davidov, D.; Grayevsky, A.

    1978-01-01

    The hydrogen sorption properties of the Lasub(1-x)Casub(x)Ni 5 and La(Nisub(1-x)Cusub(x)) 5 systems were investigated at various temperatures and at pressures up to 20 atm. It was found that initial substitution of La by Ca in LaNi 5 caused an increase in the hydrogen dissociation pressure, up to Casub(0.3)Lasub(0.7)Ni 5 . In the Casub(0.3)Lasub(0.7)Ni 5 -CaNi 5 range, the dissociation pressure decreased. The absorption capacity of CaNi 5 was dependent on the purity of the sample and increased significantly at low temperatures. The stability of La(Nisub(1-x)Cusub(x)) 5 hydrides increased linearly from LaNi 5 to LaCu 5 . These features are discussed in the light of existing models of ternary and pseudoternary hydride stability. Finally, the role of the measured change in entropy ΔS in determining the occupied interstitial sites in the hydride is outlined and discussed in relation to these systems. (Auth.)

  10. Sorption behaviour of radioactive technetium in soils

    International Nuclear Information System (INIS)

    Xia Deying

    1996-01-01

    The sorption behaviour of technetium in different soils has been studied by batch experiments under aerobic conditions. The soil samples have been taken to study the characteristics and to derive the pH-Eh values. In addition, the activated carbon and reduced iron powder have been selected as additives to the JAERI sand according to the former research work, so that the technetium sorption behaviour in the artificial soils can be studied under similar conditions. The experimental results show that all these soil samples except for the gluey soil have a very small distribution coefficient for Tc, while the artificial soils have a very large distribution coefficient for Tc. Besides, for artificial soils, the distribution coefficient (R d ) values will become larger and larger when more additive is added and more contact time is allowed. The physico-chemical fixation processes and possible sorption modes have been discussed as well

  11. Sorption of Europium in zirconium silicate

    International Nuclear Information System (INIS)

    Garcia R, G.

    2004-01-01

    Some minerals have the property of sipping radioactive metals in solution, that it takes advantage to manufacture contention barriers that are placed in the repositories of nuclear wastes. The more recent investigations are focused in the development of new technologies guided to the sorption of alpha emissors on minerals which avoid their dispersion in the environment. In an effort to contribute to the understanding of this type of properties, some studies of sorption of Europium III are presented like homologous of the americium, on the surface of zirconium silicate (ZrSiO 4 ). In this work the results of sorption experiences are presented as well as the interpretation of the phenomena of the formation of species in the surface of the zirconium silicate. (Author)

  12. Sorption of radioactive technetium on pyrrhotine

    International Nuclear Information System (INIS)

    Shen, D.; Fan, X.H.; Su, X.G.; Zeng, J.S.; Dong, Y.

    2002-01-01

    The sorption behavior of technetium on pyrrhotine was studied with batch experiments and diluted sulfuric acid (less than 2.88 mol/l) was used to dissolve the technetium adsorbed on pyrrhotine. A significant sorption of technetium on pyrrhotine was observed under aerobic and anaerobic conditions, and the sorption on the mineral was supposed to be due to the reduction of TcO 4 - to insoluble TcO 2 x nH 2 O. Sorbed technetium on the mineral could be desorbed by diluted sulfuric acid. The maximum desorption ratio under aerobic conditions was much higher than that of under anaerobic conditions, meanwhile, the desorption rates under anaerobic conditions were higher than that of under aerobic conditions in the initial stage of the experiments. (author)

  13. Water sorption and transport in dry crispy bread crust

    NARCIS (Netherlands)

    Meinders, M.B.J.; Nieuwenhuijzen, van N.H.; Tromp, R.H.; Hamer, R.J.; Vliet, van T.

    2010-01-01

    Water sorption and dynamical properties of bread crust have been studied using gravimetric sorption experiments. Water uptake and loss were followed while relative humidity (RH) was stepwise in- or decreased (isotherm experiment) or varied between two adjusted values (oscillatory experiment).

  14. The sorption of acids in cellular side of apple pressing

    International Nuclear Information System (INIS)

    Asoev, M.G.; Mukhiddinov, Z.K.

    1994-01-01

    Equilibrium swell of sample refuse after separation of water is use for study of sorption of hydrochloric acid. Quantity adsorb acids set a price to difference her concentration before and after equilibrium sorption

  15. Molecular simulation of polycyclic aromatic hydrocarbon sorption to black carbon

    NARCIS (Netherlands)

    Haftka, J.J.H.; Parsons, J.R.; Govers, H.A.J.

    2009-01-01

    Strong sorption of hydrophobic organic contaminants to soot or black carbon (BC) is an important environmental process limiting the bioremediation potential of contaminated soils and sediments. Reliable methods to predict BC sorption coefficients for organic contaminants are therefore required. A

  16. Tritium sorption on protective coatings for concrete

    International Nuclear Information System (INIS)

    Miller, J.M.; Senohrabek, J.A.; Allsop, P.A.

    1992-11-01

    Because of the high sorption level of tritium on unprotected concrete, a program to examine the effectiveness of various concrete coatings and sealants in reducing tritium sorption was undertaken, and various exposure conditions were examined. Coatings of epoxy, polyurethane, bituminous sealant, bituminous sealant covered with polyvinylidene chloride wrap, alkyd paint, and sodium silicate were investigated with tritium (HTO) vapor concentration, humidity and contact time being varied. An exposure to HT was also carried out, and the effect of humidity on the tritium desorption rate was investigated. The relative effectiveness of the coatings was in the order of bituminous sealant + wrap > bituminous sealant > solvent-based epoxy > 100%-solids epoxy > alkyd paint > sodium silicate. The commercially available coatings for concrete resulted in tritium sorption being reduced to less than 7% of unprotected concrete. This was improved to ∼0.1% with the use of the Saran wrap (polyvinylidene chloride). The amount of tritium sorbed was proportional to tritium concentration. The total tritium sorbed decreased with an increase in humidity. A saturation effect was observed with increasing exposure time for both the coated and unprotected samples. Under the test conditions, complete saturation was not achieved within the maximum 8-hour contact time, except for the solvent-based epoxy. The desorption rate increased with a higher-humidity air purge stream. HT desorbed more rapidly than HTO, but the amount sorbed was smaller. The experimental program showed that HTO sorption by concrete can be significantly reduced with the proper choice of coating. However, tritium sorption on concrete and proposed coatings will continue to be a concern until the effects of the various conditions that affect the adsorption and desorption of tritium are firmly established for both chronic and acute tritium release conditions. Material sorption characteristics must also be considered in

  17. On the derivation of a sorption database

    International Nuclear Information System (INIS)

    Ewart, F.T.; Haworth, A.; Wisbey, S.J.

    1992-01-01

    The safety arguments in support of many radioactive waste repository concepts are heavily dependent on the existence of a sorption reaction. Such a reaction will, in the near field, reduce the magnitude of the release of a number of hazardous radionuclides so that their release to the geosphere is dispersed in time. In the geosphere, the sorption reactions provide a mechanism whereby the migration of the elements released from the repository is retarded and the radioisotopes then subsequently decay. The processes involved in sorption cannot in many cases be satisfactorily represented in thermodynamic terms such as are employed in the description of dissolution and precipitation. Experiments that investigate these reactions are not easy to perform. The sorption parameters that are obtained experimentally for the near field relate, in the UK case, to sorption on to a cementitious surface. These surfaces, since they consist substantially of calcium hydroxide or calcium silicate hydrates, control the aqueous chemistry, do not permit pH changes to be made and limit the range of concentrations of sorbate that may be used. In the far field, on the other hand, the surfaces are not in general so active with respect to the solution chemistry and data can be obtained across a wide spectrum of aqueous chemistries. These data, although they may be useful in testing and parameterizing models, may not have validity under field conditions since the minerals will, inevitably, react to the changes in water chemistry, over geological timescales. The uncertainties in the experimental data are, for many elements and solids, balanced by a reasonable agreement between workers in the values of the parameters used to describe sorption. 22 refs., 1 fig., 1 tab

  18. Sorption Properties of Some Romanian Gingerbread

    Directory of Open Access Journals (Sweden)

    Tulbure Anca

    2014-06-01

    Full Text Available Water activity of gingerbread is very important for keeping the product freshness and shelf life. Water activity is influenced by composition, water content and temperature. The water content of gingerbread could vary according with storage condition. i.e. rH. 11 gingerbread samples were analysed. The water content and water activity lies between 7.0 and 12.6% and respectively 0.590 and 0.715. The sorption isotherms were determined at 30°C by gravimetric method. The moisture sorption is influenced by composition, especially sweeteners and humectants. Honey and invert sugar have the same impact on gingerbread higroscopicity.

  19. Sorption of radionuclides on hard rocks

    International Nuclear Information System (INIS)

    Berry, J.A.; Bourke, P.J.; Green, A.; Littleboy, A.K.

    1987-09-01

    Methods for measuring sorption on hard rocks, particularly of strontium, caesium, neptunium and americium on Darley Dale sandstone and Welsh slate have been investigated. The methods tried included batch tests with crushed rock and tests of simultaneous diffusion and convection with sorption on intact rock. High pressures (800m H 2 O) were used in the convective tests to pump water quickly through the rock samples and to measure high sorptivities in times shorter than those needed in the diffusive methods with intact samples. (author)

  20. A Sorption Hysteresis Model For Cellulosic Materials

    DEFF Research Database (Denmark)

    Frandsen, Henrik Lund; Damkilde, Lars

    2006-01-01

    The equilibrium concentration of adsorbed water in cellulosic materials is dependent on the history of the variations of vapor pressure in the ambient air, i.e. sorption hysteresis. Existing models to describe this phenomenon such as the independent domain theory have numerical drawbacks and....../or imply accounting for the entire history variations of every material point. This paper presents a sorption hysteresis model based on a state formulation and expressed in closed-form solutions, which makes it suitable for implementation into a numerical method....

  1. Sorption of natural uranium by algerian bentonite

    International Nuclear Information System (INIS)

    Megouda, N.; Kadi, H.; Hamla, M.S.; Brahimi, H.

    2004-01-01

    Full text.Batch sorption experiments have been used to assess the sorption behaviour of uranium onto natural and drilling bentonites. The operating parameters (pH, aolis-liquid ratio, particle size, time and initial uranium concentration) influenced the rate of adsorption. The distribution coefficient (Kd) range values at equilibrium time are 45.95-1079.26 ml/g and 32.81-463053 ml/g for the drilling and natural bentonites respectively. The equilibrium isotherms show that the data correlate with both Freundlich and Langmuir models

  2. Experimental study on an innovative multifunction heat pipe type heat recovery two-stage sorption refrigeration system

    International Nuclear Information System (INIS)

    Li, T.X.; Wang, R.Z.; Wang, L.W.; Lu, Z.S.

    2008-01-01

    An innovative multifunction heat pipe type sorption refrigeration system is designed, in which a two-stage sorption thermodynamic cycle based on two heat recovery processes was employed to reduce the driving heat source temperature, and the composite sorbent of CaCl 2 and activated carbon was used to improve the mass and heat transfer performances. For this test unit, the heating, cooling and heat recovery processes between two reactive beds are performed by multifunction heat pipes. The aim of this paper is to investigate the cycled characteristics of two-stage sorption refrigeration system with heat recovery processes. The two sub-cycles of a two-stage cycle have different sorption platforms though the adsorption and desorption temperatures are equivalent. The experimental results showed that the pressure evolutions of two beds are nearly equivalent during the first stage, and desorption pressure during the second stage is large higher than that in the first stage while the desorption temperatures are same during the two operation stages. In comparison with conventional two-stage cycle, the two-stage cycle with heat recovery processes can reduce the heating load for desorber and cooling load for adsorber, the coefficient of performance (COP) has been improved more than 23% when both cycles have the same regeneration temperature of 103 deg. C and the cooling water temperature of 30 deg. C. The advanced two-stage cycle provides an effective method for application of sorption refrigeration technology under the condition of low-grade temperature heat source or utilization of renewable energy

  3. The sorption behaviour of 99Tc on activated carbon

    International Nuclear Information System (INIS)

    Xia Deying; Zeng Jishu

    2004-01-01

    The sorption behaviour of 99 Tc on apricot-pit activated carbon with batch experiment is studied. The influence of such factors as sorbent particle size, temperature, pH value on sorption ratio, and the Freundlich sorption isotherms are reported in this paper. (author)

  4. Suitability of Moshi Pumice for Phosphorus Sorption in Constructed ...

    African Journals Online (AJOL)

    The study of Moshi Pumice's phosphorus sorption behaviours and properties was carried out in laboratory scale where by 1-2 mm, 2-4 mm and 4-8 mm grains were tested using batch experiments. The results show that Moshi Pumice has high phosphorus sorption capacity. The sorption capacity for the Moshi Pumice was ...

  5. Phosphorus sorption in relation to soil grain size and geochemical ...

    African Journals Online (AJOL)

    By using stepwise regression, the combination of Al, Fe, clay and Ca predicted more than 94% of the variation in the P sorption capacity of soils samples from Simiyu and Kagera basins. These four soil properties, which are strongly related to P sorption, could therefore be used as quick tests for predicting the P sorption ...

  6. Sorption of Heterocyclic Organic Compounds to Multiwalled Carbon Nanotubes.

    Science.gov (United States)

    Metzelder, Florian; Funck, Matin; Schmidt, Torsten C

    2018-01-16

    Sorption is an important natural and technical process. Sorption coefficients are typically determined in batch experiments, but this may be challenging for weakly sorbing compounds. An alternative method enabling analysis of those compounds is column chromatography. A column packed with the sorbent is used and sorption data are determined by relating sorbate retention to that of a nonretarded tracer. In this study, column chromatography was applied for the first time to study sorption of previously hardly investigated heterocyclic organic compounds to multiwalled carbon nanotubes (MWCNTs). Sorption data for these compounds are very limited in literature, and weak sorption is expected from predictions. Deuterium oxide was used as nonretarded tracer. Sorption isotherms were well described by the Freundlich model and data showed reasonable agreement with predicted values. Sorption was exothermic and physisorption was observed. H-bonding may contribute to overall sorption, which is supported by reduced sorption with increasing ionic strength due to blocking of functional groups. Lowering pH reduced sorption of ionizable compounds, due to electrostatic repulsion at pH 3 where sorbent as well as sorbates were positively charged. Overall, column chromatography was successfully used to study sorption of heterocyclic compounds to MWCNTs and could be applied for other carbon-based sorbents.

  7. Attenuation of polychlorinated biphenyl sorption to charcoal by humic acids

    NARCIS (Netherlands)

    Koelmans, A.A.; Meulman, B.; Meijer, T.; Jonker, M.T.O.

    2009-01-01

    Strong sorption to black carbon may limit the environmental risks of organic pollutants, but interactions with cosorbing humic acid (HA) may interfere. We studied the attenuative effect of HA additions on the sorption of polychlorinated biphenyls (PCBs) to a charcoal. "Intrinsic" sorption to

  8. Sorption mechanisms of perfluorinated compounds on carbon nanotubes

    International Nuclear Information System (INIS)

    Deng Shubo; Zhang Qiaoying; Nie Yao; Wei Haoran; Wang Bin; Huang Jun; Yu Gang; Xing Baoshan

    2012-01-01

    Sorption of perfluorinated compounds (PFCs) on carbon nanotubes (CNTs) is critical for understanding their subsequent transport and fate in aqueous environments, but the sorption mechanisms remain largely unknown. In this study, the sorption of six PFCs on CNTs increased with increasing C-F chain length when they had a same functional group, and the CNTs with hydroxyl and carboxyl groups had much lower adsorbed amount than the pristine CNTs, indicating that hydrophobic interaction dominated the sorption of PFCs on the CNTs. Electrostatic repulsion suppressed the sorption of PFCs on the CNTs, resulting in the lower sorption with increasing pH. Hydrogen bonding interaction was negligible. The hydrophobic C-F chains can be closely adsorbed on the CNTs surface in parallel to the axis or along the curvature, making it impossible to form micelles on the CNT surface, leading to the lower sorption than other adsorbents. Highlights: ► Sorption capacities of PFOA on different CNTs are less than that on activated carbon and resins. ► Hydrophobic interaction is principally involved in the sorption of PFCs on CNTs. ► Electrostatic repulsion suppresses the sorption of PFCs on CNTs. - Hydrophobic interaction dominated the sorption of perfluorinated compounds on carbon nanotubes, while electrostatic repulsion suppressed their sorption.

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

    International Nuclear Information System (INIS)

    Puls, M.P.; Rogowski, A.J.

    1980-11-01

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

  10. High pressure hydriding of sponge-Zr in steam-hydrogen mixtures

    International Nuclear Information System (INIS)

    Kim, Y.S.

    1997-01-01

    Hydriding kinetics of thin sponge-Zr layers metallurgically bonded to a Zircaloy disk has been studied by thermogravimetry in the temperature range 350-400 C in 7 MPa hydrogen-steam mixtures. Some specimens were prefilmed with a thin oxide layer prior to exposure to the reactant gas; all were coated with a thin layer of gold to avoid premature reaction at edges. Two types of hydriding were observed in prefilmed specimens, viz., a slow hydrogen absorption process that precedes an accelerated (massive) hydriding. At 7 MPa total pressure, the critical ratio of H 2 /H 2 O above which massive hydriding occurs at 400 C is ∝200. The critical H 2 /H 2 O ratio is shifted to ∝2.5 x 10 3 at 350 C. The slow hydriding process occurs only when conditions for hydriding and oxidation are approximately equally favorable. Based on maximum weight gain, the specimen is completely converted to δ-ZrH 2 by massive hydriding in ∝5 h at a hydriding rate of ∝10 -6 mol H/cm 2 s. Incubation times of 10-20 h prior to the onset of massive hydriding increases with prefilm oxide thickness in the range of 0-10 μm. By changing to a steam-enriched gas, massive hydriding that initially started in a steam-starved condition was arrested by re-formation of a protective oxide scale. (orig.)

  11. Elaboration and characterization of unreported (Pr,Nd)5Ni19 hydrides

    International Nuclear Information System (INIS)

    Lemort, Lucille; Latroche, Michel; Knosp, Bernard; Bernard, Patrick

    2011-01-01

    Research highlights: → Two new compounds Pr 5 Ni 19 and Nd 5 Ni 19 have been synthesized and their crystallographic structures have been determined. → Two polymorphic types are reported to coexist for the same composition, one rhombohedral and one hexagonal. → The hydrogen sorption properties of these two novel compounds have been measured and they exhibit capacities of 1.33%(wt) for Pr 5 Ni 19 and 1.17%(wt) for Nd 5 Ni 19 under 10 MPa. - Abstract: In this study two new compounds have been synthesized: Pr 5 Ni 19 and Nd 5 Ni 19 . The crystallographic structures as well as the thermodynamic properties of the hydrogen absorbing compounds Pr 5 Ni 19 and Nd 5 Ni 19 have been determined. Both compounds exist under two polymorphic types that can be described as the stacking along the c axis of two different subunits [(Pr,Nd) 2 Ni 4 ] and [(Pr,Nd)Ni 5 ]: the hexagonal (2H) Pr 5 Co 19 -type structure (space group P6 3 /mmc) and the rhombohedral (3R) Ce 5 Co 19 -type structure (space group R-3m). The two compounds are able to form hydrides at room temperature, in the pressure range of 0-10 MPa. They show desorption pressure plateaux around 0.8 MPa for Pr 5 Ni 19 and 1 MPa for Nd 5 Ni 19 and exhibit capacities under 10 MPa of 1.33 wt% for Pr 5 Ni 19 and 1.17 wt% for Nd 5 Ni 19 at the first cycle.

  12. Elaboration and characterization of unreported (Pr,Nd){sub 5}Ni{sub 19} hydrides

    Energy Technology Data Exchange (ETDEWEB)

    Lemort, Lucille [ICMPE CMTR CNRS UMR 7182, 2-8 rue Henri Dunant, 94320 Thiais Cedex (France); Latroche, Michel, E-mail: michel.latroche@icmpe.cnrs.fr [ICMPE CMTR CNRS UMR 7182, 2-8 rue Henri Dunant, 94320 Thiais Cedex (France); Knosp, Bernard; Bernard, Patrick [SAFT, Direction de la Recherche, 111-113 Boulevard Alfred Daney, 33074 Bordeaux (France)

    2011-09-15

    Research highlights: > Two new compounds Pr{sub 5}Ni{sub 19} and Nd{sub 5}Ni{sub 19} have been synthesized and their crystallographic structures have been determined. > Two polymorphic types are reported to coexist for the same composition, one rhombohedral and one hexagonal. > The hydrogen sorption properties of these two novel compounds have been measured and they exhibit capacities of 1.33%(wt) for Pr{sub 5}Ni{sub 19} and 1.17%(wt) for Nd{sub 5}Ni{sub 19} under 10 MPa. - Abstract: In this study two new compounds have been synthesized: Pr{sub 5}Ni{sub 19} and Nd{sub 5}Ni{sub 19}. The crystallographic structures as well as the thermodynamic properties of the hydrogen absorbing compounds Pr{sub 5}Ni{sub 19} and Nd{sub 5}Ni{sub 19} have been determined. Both compounds exist under two polymorphic types that can be described as the stacking along the c axis of two different subunits [(Pr,Nd){sub 2}Ni{sub 4}] and [(Pr,Nd)Ni{sub 5}]: the hexagonal (2H) Pr{sub 5}Co{sub 19}-type structure (space group P6{sub 3}/mmc) and the rhombohedral (3R) Ce{sub 5}Co{sub 19}-type structure (space group R-3m). The two compounds are able to form hydrides at room temperature, in the pressure range of 0-10 MPa. They show desorption pressure plateaux around 0.8 MPa for Pr{sub 5}Ni{sub 19} and 1 MPa for Nd{sub 5}Ni{sub 19} and exhibit capacities under 10 MPa of 1.33 wt% for Pr{sub 5}Ni{sub 19} and 1.17 wt% for Nd{sub 5}Ni{sub 19} at the first cycle.

  13. Mathematical model of the sorption phenomenon of methanol in activated coal

    Energy Technology Data Exchange (ETDEWEB)

    Cortes, Farid B.; Chejne, Farid; Mejia, Juan M.; Londono, Carlos A. [Grupo de Termodinamica Aplicada y Energias Alternativas - Instituto de Energia, Facultad de Minas, Universidad Nacional de Colombia, sede Medellin (Colombia)

    2009-05-15

    A transient model of a sorption refrigerator using activated carbon/methanol pair is presented. It is a non-uniform pressure model conformed by the mass, energy and momentum balance equations in cylindrical coordinates, for the activated coal bed contained in the adsorber. The results obtained from the simulation were suitably validated by the experimental information obtained from field test data and from data reported in the literature, presenting errors below 1.6% for each cycle step. The model allows to get data of temperature, pressure, density and gas velocity profiles in radial direction, as well as the solid temperature and the quantity of adsorbed methanol in the activated carbon bed in adsorption/evaporation and desorption/condensation steps. (author)

  14. Mathematical model of the sorption phenomenon of methanol in activated coal

    International Nuclear Information System (INIS)

    Cortes, Farid B.; Chejne, Farid; Mejia, Juan M.; Londono, Carlos A.

    2009-01-01

    A transient model of a sorption refrigerator using activated carbon/methanol pair is presented. It is a non-uniform pressure model conformed by the mass, energy and momentum balance equations in cylindrical coordinates, for the activated coal bed contained in the adsorber. The results obtained from the simulation were suitably validated by the experimental information obtained from field test data and from data reported in the literature, presenting errors below 1.6% for each cycle step. The model allows to get data of temperature, pressure, density and gas velocity profiles in radial direction, as well as the solid temperature and the quantity of adsorbed methanol in the activated carbon bed in adsorption/evaporation and desorption/condensation steps.

  15. Bed Bugs FAQs

    Science.gov (United States)

    ... Europe. Bed bugs have been found in five-star hotels and resorts and their presence is not ... Health – Division of Parasitic Diseases Email Recommend Tweet YouTube Instagram Listen Watch RSS ABOUT About CDC Jobs ...

  16. Bed Bug Information Clearinghouse

    Science.gov (United States)

    Its purpose is to help states, communities, and consumers in efforts to prevent and control bed bug infestations. Currently includes only reviewed material from federal/state/local government agencies, extension services, and universities.

  17. Particle fuel bed tests

    International Nuclear Information System (INIS)

    Horn, F.L.; Powell, J.R.; Savino, J.M.

    1985-01-01

    Gas-cooled reactors, using packed beds of small diameter coated fuel particles have been proposed for compact, high-power systems. The particulate fuel used in the tests was 800 microns in diameter, consisting of a thoria kernel coated with 200 microns of pyrocarbon. Typically, the bed of fuel particles was contained in a ceramic cylinder with porous metallic frits at each end. A dc voltage was applied to the metallic frits and the resulting electric current heated the bed. Heat was removed by passing coolant (helium or hydrogen) through the bed. Candidate frit materials, rhenium, nickel, zirconium carbide, and zirconium oxide were unaffected, while tungsten and tungsten-rhenium lost weight and strength. Zirconium-carbide particles were tested at 2000 K in H 2 for 12 hours with no visible reaction or weight loss

  18. The effect of compositional changes on the structural and hydrogen storage properties of (La–Ce)Ni5 type intermetallics towards compounds suitable for metal hydride hydrogen compression

    International Nuclear Information System (INIS)

    Odysseos, M.; De Rango, P.; Christodoulou, C.N.; Hlil, E.K.; Steriotis, T.; Karagiorgis, G.; Charalambopoulou, G.; Papapanagiotou, T.; Ampoumogli, A.; Psycharis, V.; Koultoukis, E.; Fruchart, D.; Stubos, A.

    2013-01-01

    Graphical abstract: The effect of the partial substitution of La with Ce on the crystal structure and the final hydrogen storage properties of the alloys. Highlights: ► Absorption-based systems exploit the properties of reversible metal hydrides. ► AB5 intermetallics are mostly popular for thermal desorption compressors. ► Investigation of H2 absorption/desorption properties of LaNi5 and its derivatives. ► LaNi5 thermodynamic properties adjustment by partially replacing La with rare earths. -- Abstract: The present work has been aiming at the synthesis and study of a series of La 1−x Ce x Ni 5 (x = 0, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8) alloys in an attempt to investigate possible alterations of the hydrogen absorption/desorption properties The alloys were prepared by induction melting of the constituent elements. The systematic characterization of all new compounds by means of XRD and hydrogen sorption measurements revealed the effect of the partial substitution of La with Ce on the crystal structure and the final hydrogen storage properties of the alloys. Extensive absorption/desorption experiments (Van’t Hoff diagrams) have shown that such alloys can be used to build a metal hydride compressor (MHC), compressing H 2 gas from 0.2 MPa to 4.2 MPa using cold (20 °C) and hot (80 °C) water

  19. Effects of natural organic matter on PCB-activated carbon sorption kinetics: implications for sediment capping applications.

    Science.gov (United States)

    Fairey, Julian L; Wahman, David G; Lowry, Gregory V

    2010-01-01

    In situ capping of polychlorinated biphenyl (PCB)-contaminated sediments with a layer of activated carbon has been proposed, but several questions remain regarding the long-term effectiveness of this remediation strategy. Here, we assess the degree to which kinetic limitations, size exclusion effects, and electrostatic repulsions impaired PCB sorption to activated carbon. Sorption of 11 PCB congeners with activated carbon was studied in fixed bed reactors with organic-free water (OFW) and Suwannee River natural organic matter (SR-NOM), made by reconstituting freeze-dried SR-NOM at a concentration of 10 mg L(-1) as carbon. In the OFW test, no PCBs were detected in the column effluent over the 390-d study, indicating that PCB-activated carbon equilibrium sorption capacities may be achieved before breakthrough even at the relatively high hydraulic loading rate (HLR) of 3.1 m h(-1). However, in the SR-NOM fixed-bed test, partial PCB breakthrough occurred over the entire 320-d test (HLRs of 3.1-, 1.5-, and 0.8 m h(-1)). Simulations from a modified pore and surface diffusion model indicated that external (film diffusion) mass transfer was the dominant rate-limiting step but that internal (pore diffusion) mass transfer limitations were also present. The external mass transfer limitation was likely caused by formation of PCB-NOM complexes that reduced PCB sorption through a combination of (i) increased film diffusion resistance; (ii) size exclusion effects; and (iii) electrostatic repulsive forces between the PCBs and the NOM-coated activated carbon. However, the seepage velocities in the SR-NOM fixed bed test were about 1000 times higher than would be expected in a sediment cap. Therefore, additional studies are needed to assess whether the mass transfer limitations described here would be likely to manifest themselves at the lower seepage velocities observed in practice.

  20. Shielding requirements for particle bed propulsion systems

    Science.gov (United States)

    Gruneisen, S. J.

    1991-06-01

    Nuclear Thermal Propulsion systems present unique challenges in reliability and safety. Due to the radiation incident upon all components of the propulsion system, shielding must be used to keep nuclear heating in the materials within limits; in addition, electronic control systems must be protected. This report analyzes the nuclear heating due to the radiation and the shielding required to meet the established criteria while also minimizing the shield mass. Heating rates were determined in a 2000 MWt Particle Bed Reactor (PBR) system for all materials in the interstage region, between the reactor vessel and the propellant tank, with special emphasis on meeting the silicon dose criteria. Using a Lithium Hydride/Tungsten shield, the optimum shield design was found to be: 50 cm LiH/2 cm W on the axial reflector in the reactor vessel and 50 cm LiH/2 cm W in a collar extension of the inside shield outside of the pressure vessel. Within these parameters, the radiation doses in all of the components in the interstage and lower tank regions would be within acceptable limits for mission requirements.

  1. Hydration and sorption characteristics of a polyfunctional weak-base anion exchanger after the sorption of vanillin and ethylvanillin

    Science.gov (United States)

    Rodionova, D. O.; Voronyuk, I. V.; Eliseeva, T. V.

    2016-07-01

    Features of the sorption of substituted aromatic aldehydes by a weak-base anion exchanger under equilibrium conditions are investigated using vanillin and ethylvanillin as examples. Analysis of the sorption isotherms of carbonyl compounds at different temperatures allows us to calculate the equilibrium characteristics of their sorption and assess the entropy and enthalpy contributions to the energy of the process. Hydration characteristics of the macroporous weak-base anion exchanger before and after the sorption of aromatic aldehydes are compared.

  2. Sorption Modeling and Verification for Off-Gas Treatment

    Energy Technology Data Exchange (ETDEWEB)

    Tavlarides, Lawrence [Syracuse Univ., NY (United States); Yiacoumi, Sotira [Georgia Inst. of Technology, Atlanta, GA (United States); Tsouris, Costas [Georgia Inst. of Technology, Atlanta, GA (United States); Gabitto, Jorge [Prairie View Texas A& M; DePaoli, David [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-12-20

    processes. These models were built on a numerical framework for solving conservation law problems in one-dimensional geometries such as spheres, cylinders, and lines. Coupled with the framework are specific models for adsorption in commercial adsorbents, such as zeolites and mordenites. Utilizing this modeling approach, the authors were able to accurately describe and predict adsorption kinetic data obtained from experiments at a variety of different temperatures and gas phase concentrations. A demonstration of how these models, and framework, can be used to simulate adsorption in fixed- bed columns is provided. The CO2 absorption work involved modeling with supportive experimental information. A dynamic model was developed to simulate CO2 absorption using high alkaline content water solutions. The model is based upon transient mass and energy balances for chemical species commonly present in CO2 absorption. A computer code was developed to implement CO2 absorption with a chemical reaction model. Experiments were conducted in a laboratory scale column to determine the model parameters. The influence of geometric parameters and operating variables on CO2 absorption was studied over a wide range of conditions. Continuing work could employ the model to control column operation and predict the absorption behavior under various input conditions and other prescribed experimental perturbations. The value of the validated models and numerical frameworks developed in this project is that they can be used to predict the sorption behavior of off-gas evolved during the reprocessing of nuclear waste and thus reduce the cost of the experiments. They can also be used to design sorption processes based on concentration limits and flow-rates determined at the plant level.

  3. Sorption ability of the soil and its impact on environmental contamination

    Science.gov (United States)

    Gargošová, Helena Zlámalová; Vávrová, Milada

    2014-01-01

    From the physical point of view, soil is a heterogenic polydisperse system. It often becomes a place of a secondary contamination during extinguishing uncontrolled areal fires in nature. Foam extinguishing agents (FEAs), used at these events, basically contain surface active substances and perfluorinated compounds. These tend to be captured in the soil matrix due to their specific properties. Contaminants could be partly flushed out with rainwater, which causes several times dilution of contamination and lower ecotoxic activity. However in the dry season, foam solution infiltrates into the bed soil without any dilution. This study deals with the direct influence of soil the sorption complex on ecotoxicity of five selected FEAs, i.e. Expyrol F 15, Finiflam F 15, Moussol APS F 15, Pyrocool B and Sthamex F 15. The substances tested were prepared in concentration of work solution and then applied on standard soil matrix LUFA 2.3. For experimental purposes, a column infiltration apparatus was designed and compiled. Filtrates were collected and then tested using the plant organisms Sinapis alba and Allium cepa L. The study compared ecotoxicologic effects of filtrates with an original work solution. Moussol APS F 15 seems to be the least ecotoxic of the FEAs tested. A direct influence of soil sorption complex onto ecotoxicity reduction was also established. This finding demonstrates the sorption ability of soil particles and ion exchange activity of the soil matrix. It is a positive finding for biota of aquatic environment, yet at the expense of those in soil. PMID:26109897

  4. A suggested approach toward measuring sorption and applying sorption data to repository performance assessment

    International Nuclear Information System (INIS)

    Rundberg, R.S.

    1991-01-01

    The sorption of radioisotopes in relation to geologic disposal of radioactive wastes is discussed. Properties of the radioactive materials, rocks, and minerals, and the chemistry involved are described. 51 refs., 12 figs. CBS

  5. Simulation of a high efficiency multi-bed adsorption heat pump

    International Nuclear Information System (INIS)

    TeGrotenhuis, W.E.; Humble, P.H.; Sweeney, J.B.

    2012-01-01

    Attaining high energy efficiency with adsorption heat pumps is challenging due to thermodynamic losses that occur when the sorbent beds are thermally cycled without effective heat recuperation. The multi-bed concept described here enables high efficiency by effectively transferring heat from beds being cooled to beds being heated. A simplified lumped-parameter model and detailed finite element analysis are used to simulate a sorption compressor, which is used to project the overall heat pump coefficient of performance. Results are presented for ammonia refrigerant and a nano-structured monolithic carbon sorbent specifically modified for the application. The effects of bed geometry and number of beds on system performance are explored, and the majority of the performance benefit is obtained with four beds. Results indicate that a COP of 1.24 based on heat input is feasible at AHRI standard test conditions for residential HVAC equipment. When compared on a basis of primary energy input, performance equivalent to SEER 13 or 14 are theoretically attainable with this system. - Highlights: ► A multi-bed concept for adsorption heat pumps is capable of high efficiency. ► Modeling is used to simulate sorption compressor and overall heat pump performance. ► Results are presented for ammonia refrigerant and a nano-structured monolithic carbon sorbent. ► The majority of the efficiency benefit is obtained with four beds. ► Predicted COP as high as 1.24 for cooling is comparable to SEER 13 or 14 for electric heat pumps.

  6. Sorption of fission nuclides on model milk components. II. Sorption of radiostrontium on hydroxyapatite in milk and whey

    International Nuclear Information System (INIS)

    Rosskopfova, O.; Kopunec, R.; Matel, L.; Macasek, F.

    1999-01-01

    In this work the whey was chosen as a model solution of liquid phase for sorption study of strontium on hydroxyapatite. The whey was obtained using two methods - ultracentrifugation and precipitation of casein. The sorption was studied at a different pH and at a different concentration of calcium. The sorption of strontium on hydroxyapatite from milk was studied, too. (authors)

  7. Development of mechanistic sorption model and treatment of uncertainties for Ni sorption on montmorillonite/bentonite

    International Nuclear Information System (INIS)

    Ochs, Michael; Ganter, Charlotte; Tachi, Yukio; Suyama, Tadahiro; Yui, Mikazu

    2011-02-01

    Sorption and diffusion of radionuclides in buffer materials (bentonite) are the key processes in the safe geological disposal of radioactive waste, because migration of radionuclides in this barrier is expected to be diffusion-controlled and retarded by sorption processes. It is therefore necessary to understand the detailed/coupled processes of sorption and diffusion in compacted bentonite and develop mechanistic /predictive models, so that reliable parameters can be set under a variety of geochemical conditions relevant to performance assessment (PA). For this purpose, JAEA has developed the integrated sorption and diffusion (ISD) model/database in montmorillonite/bentonite systems. The main goal of the mechanistic model/database development is to provide a tool for a consistent explanation, prediction, and uncertainty assessment of K d as well as diffusion parameters needed for the quantification of radionuclide transport. The present report focuses on developing the thermodynamic sorption model (TSM) and on the quantification and handling of model uncertainties in applications, based on illustrating by example of Ni sorption on montmorillonite/bentonite. This includes 1) a summary of the present state of the art of thermodynamic sorption modeling, 2) a discussion of the selection of surface species and model design appropriate for the present purpose, 3) possible sources and representations of TSM uncertainties, and 4) details of modeling, testing and uncertainty evaluation for Ni sorption. Two fundamentally different approaches are presented and compared for representing TSM uncertainties: 1) TSM parameter uncertainties calculated by FITEQL optimization routines and some statistical procedure, 2) overall error estimated by direct comparison of modeled and experimental K d values. The overall error in K d is viewed as the best representation of model uncertainty in ISD model/database development. (author)

  8. Gas Sorption, Diffusion, and Permeation in Nafion

    KAUST Repository

    Mukaddam, Mohsin Ahmed; Litwiller, Eric; Pinnau, Ingo

    2015-01-01

    The gas permeability of dry Nafion films was determined at 2 atm and 35 °C for He, H2, N2, O2, CO2, CH4, C2H6, and C3H8. In addition, gas sorption isotherms were determined by gravimetric and barometric techniques as a function of pressure up to 20

  9. Development of a microminiature sorption cooler

    NARCIS (Netherlands)

    Burger, Johannes; Holland, Harry; ter Brake, Marcel; Rogalla, Horst; Wade, Larry

    1997-01-01

    The development of a microcooler for operations below 80 K, for low temperature electronic devices requiring small cooling powers of the order of 10 mW is described. A sorption compressor combined with Joule-Thomson (JT) expansion was selected for miniaturization. The advantage of the system is

  10. Sorption of radiocalcium on human hair

    International Nuclear Information System (INIS)

    Rakovic, M.; Pilecka, N.

    1987-01-01

    The sorption of 45 Ca on hair from a 45 CaCl 2 solution (2.5x10 -3 mol l -1 ) was studied. The calcium amounts sorbed in 1 min to 5 h range between 0.8 and 7.2% with respect to the originally present calcium in hair. (author) 3 refs

  11. Sorption of methanol in alkali exchange zeolites

    NARCIS (Netherlands)

    Rep, M.; Rep, M.; Corma, Avelino; Palomares, A.E.; Palomares gimeno, A.E.; van Ommen, J.G.; Lefferts, Leonardus; Lercher, J.A.

    2000-01-01

    Metal cation methanol sorption complexes in MFI (ZSM5), MOR and X have been studied by in situ i.r. spectroscopy in order to understand the nature of interactions of methanol in the molecular sieve pores. The results show that (a) a freely vibrating hydroxy and methyl group of methanol exist on

  12. Radionuclide sorption database for Swiss safety assessment

    International Nuclear Information System (INIS)

    McKinley, I.G.; Hadermann, J.

    1984-10-01

    Recommended sorption data for use in transport models for a Swiss High-Level Waste repository are presented. The models used in 'Project Gewaehr 1985' assume linear sorption isotherms and require elemental partition coefficient (Kd) data. On the basis of a literature search 'realistic' Kd data for 22 elements have been selected for weathered crystalline rock and sediments in contact with a reducing groundwater and also sediments with a less reducing groundwater. In an appendix sorption data for 28 elements on bentonite backfill are given. These data are supplemented with 'conservative' estimates taken to represent minimum reasonable values. Available data are discussed for each element clearly exhibiting (i) the large gaps in knowledge, (ii) their unbalanced distribution between different elements and, hence, (iii) the need for further experiments in the laboratory, the field and analogue studies. An overview of the theoretical concepts of sorption, experimental methodology and data interpretation is given in order to put the values into context. General problem areas are identified. (Auth.)

  13. Radionuclide sorption kinetics and column sorption studies with Columbia River basalts

    International Nuclear Information System (INIS)

    Barney, G.S.

    1983-09-01

    The kinetics of radionuclide sorption and desorption reactions in basalt-groundwater systems were evaluated at 60 degrees C using a batch equilibration method. It was found that many sorption reactions on surfaces of fresh (unaltered) basalt from the Umtanum and Cohassett flows are slow. Some reactions require more than 50 days to reach a steady state. Sorption of neptunium and uranium in oxidizing (air saturated) groundwater appears to be controlled by slow reduction of these elements by the basalt surfaces. The resulting lower oxidation states are more strongly sorbed. Technetium and selenium, which are anionic under oxidizing conditions, are not measurably sorbed on fresh basalt surfaces, but are slightly sorbed on the altered surfaces of flow top basalt. Under reducing conditions, where the groundwater contains dilute hydrazine, sorption is faster for neptunium, uranium, technetium, selenium, and lead. Plutonium sorption rates were not affected by the groundwater Eh. It was shown that radium was precipitated rather than sorbed under the conditions of these experiments. Umtanum flow top material sorbed radionuclides much faster than fresh basalt surfaces due to its greater surface area and cation exchange capacity. Desorption rates for plutonium, uranium, neptunium, technetium, and selenium were generally much less than sorption rates (especially for reducing conditions). These radionuclides are irreversibly sorbed on the basalts. 25 refs., 20 figs., 19 tabs

  14. Radionuclide sorption on crushed and intact granitic rock

    International Nuclear Information System (INIS)

    Eriksen, Tryggve E.; Locklund, Birgitta

    1989-05-01

    The specific surface areas and distribution ratios for sorption of 85 Sr, 137 Cs and 152 Eu were measured for crushed and intact granite rock. The experimental data can be accommodated by a sorption model encompassing sorption on outer and inner surface. It is clearly demonstrated that the time required to obtain reliable Kd-values for the sorption of strongly sorbing radionuclides like 152 Eu is very long due to solution depletion and slow diffusion into the rock. A combination of surface area measurements and batch sorption with small particles may therefore be preferable when studying strongly sorbing nuclides. (authors) (17 figs., 6 tabs.)

  15. Sorption and migration of neptunium in porous sedimentary materials

    International Nuclear Information System (INIS)

    Tanaka, Tadao; Mukai, Masayuki; Nakayama, Shinichi

    2005-01-01

    Column migration experiments of neptunium were conducted for porous sedimentary materials: coastal sand, tuffaceous sand, ando soil, reddish soil, yellowish soil and loess, and migration behavior, sorption mechanisms and chemical formation of Np were investigated. The migration behavior of Np in each material was much different each other, due to chemical formation in solution and/or sorption mechanism of Np. Mathematical models of different concepts were applied to the experimental results to interpret the sorption mechanism and the migration behavior. It can be concluded that both of instantaneous equilibrium sorption and sorption-desorption kinetics have to be considered to model the Np migration in sedimentary materials. (author)

  16. Catalytic effect of halide additives ball milled with magnesium hydride

    Energy Technology Data Exchange (ETDEWEB)

    Malka, I.E.; Bystrzycki, J. [Department of Advanced Materials and Technologies, Military University of Technology, Kaliskiego 2, 00-908 Warsaw (Poland); Czujko, T. [Department of Advanced Materials and Technologies, Military University of Technology, Kaliskiego 2, 00-908 Warsaw (Poland); CanmetENERGY, Hydrogen Fuel Cells and Transportation Energy, Natural Resources (Canada)

    2010-02-15

    The influence of various halide additives milled with magnesium hydride (MgH{sub 2}) on its decomposition temperature was studied. The optimum amount of halide additive and milling conditions were evaluated. The MgH{sub 2} decomposition temperature and energy of activation reduction were measured by temperature programmed desorption (TPD) and differential scanning calorimetry (DSC). The difference in catalytic efficiency between chlorides and fluorides of the various metals studied is presented. The effects of oxidation state, valence and position in the periodic table for selected halides on MgH{sub 2} decomposition temperature were also studied. The best catalysts, from the halides studied, for magnesium hydride decomposition were ZrF{sub 4}, TaF{sub 5}, NbF{sub 5}, VCl{sub 3} and TiCl{sub 3}. (author)

  17. Irradiation effects on thermal properties of LWR hydride fuel

    Energy Technology Data Exchange (ETDEWEB)

    Terrani, Kurt, E-mail: terrani@berkeley.edu [University of California, 4155 Etcheverry Hall, M.C. 1730, Berkeley, CA 94720-1730 (United States); Balooch, Mehdi [University of California, 4155 Etcheverry Hall, M.C. 1730, Berkeley, CA 94720-1730 (United States); Carpenter, David; Kohse, Gordon [Massachusetts Institute of Technology, 138 Albany St., Cambridge, MA 02139 (United States); Keiser, Dennis; Meyer, Mitchell [Idaho National Laboratory, Idaho Falls, ID 83415 (United States); Olander, Donald [University of California, 4155 Etcheverry Hall, M.C. 1730, Berkeley, CA 94720-1730 (United States)

    2017-04-01

    Three hydride mini-fuel rods were fabricated and irradiated at the MIT nuclear reactor with a maximum burnup of 0.31% FIMA or ∼5 MWd/kgU equivalent oxide fuel burnup. Fuel rods consisted of uranium-zirconium hydride (U (30 wt%)ZrH{sub 1.6}) pellets clad inside a LWR Zircaloy-2 tubing. The gap between the fuel and the cladding was filled with lead-bismuth eutectic alloy to eliminate the gas gap and the large temperature drop across it. Each mini-fuel rod was instrumented with two thermocouples with tips that are axially located halfway through the fuel centerline and cladding surface. In-pile temperature measurements enabled calculation of thermal conductivity in this fuel as a function of temperature and burnup. In-pile thermal conductivity at the beginning of test agreed well with out-of-pile measurements on unirradiated fuel and decreased rapidly with burnup.

  18. Positronium hydride defects in thermochemically reduced alkaline-Earth oxides

    International Nuclear Information System (INIS)

    Monge, M.A.; Pareja, R.; Gonzalez, R.; Chen, Y.

    1997-01-01

    Thermochemical reduction of both hydrogen-doped MgO and CaO single crystals results in large concentrations of hydride (H - ) ions. In MgO crystals, positron lifetime and Doppler broadening experiments show that positrons are trapped at H - centers forming positronium hydride molecules [e + - H - ]. A value of 640 ps is obtained for the lifetime of the PsH states located in an anion vacancy In MgO positrons are also trapped at H 2- sites at low temperatures. The H 2- ions were induced in the crystals by blue light illumination. The formation of PsH states in CaO could not be conclusively established. (orig.)

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

    International Nuclear Information System (INIS)

    Greenspan, Ehud; Todreas, Neil; Taiwo, Temitope

    2009-01-01

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

  20. 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

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

    Energy Technology Data Exchange (ETDEWEB)

    Greenspan, Ehud; Todreas, Neil; Taiwo, Temitope

    2009-03-10

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

  2. Sorption of niobium on boreal forest soil

    Energy Technology Data Exchange (ETDEWEB)

    Soederlund, Mervi; Hakanen, Martti; Lehto, Jukka [Helsinki Univ. (Finland). Lab. of Radiochemistry

    2015-07-01

    The sorption of niobium (Nb) was investigated on humus and mineral soil samples taken from various depths of a four-metre deep forest soil pit on Olkiluoto Island, southwestern Finland. Mass distribution coefficients, K{sub d}, were determined in batch sorption tests. The steady state of Nb sorption was observed in the mineral soil samples already after one week of equilibration, and sorption decreased with depth from a very high value of 185000 mL/g at 0.7 m to 54000 mL/g at 3.4 m. The reason behind this decrease is probably the tenfold reduction in the specific surface area of the soil at the same depth range. Distribution coefficients were clearly lower in the humus layer (1000 mL/g). The K{sub d} values determined in pure water at a pH range of 4.7-6.5 were at a high level (above 55000 mL/g), but decreased dramatically above pH 6.5, corresponding to the change in the major Nb species from the neutral Nb(OH){sub 5} to the low-sorbing anionic Nb(OH){sub 6}{sup -} and Nb(OH){sub 7}{sup 2-}. However, the K{sub d} values in the model soil solution were in the slightly alkaline range an order of magnitude higher than in pure water, which is probably caused by the formation of calcium niobate surface precipitate or electrostatic interaction between surface-sorbed calcium and solute Nb. Among nine soil constituent minerals kaolinite performed best in retaining Nb in both pure water and model soil solution at pH 8, whereas potassium feldspar showed the poorest sorption. The K{sub d} value for kaolinite was above 500000 mL/g in both solutions, while the respective potassium feldspar values were in the range of 120-220 mL/g.

  3. Sorption behaviour of perfluoroalkyl substances in soils.

    Science.gov (United States)

    Milinovic, Jelena; Lacorte, Silvia; Vidal, Miquel; Rigol, Anna

    2015-04-01

    The sorption behaviour of three perfluoroalkyl substances (PFASs), perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA) and perfluorobutane sulfonic acid (PFBS), was studied in six soils with contrasting characteristics, especially in the organic carbon content. Sorption isotherms were obtained by equilibrating the soil samples with 0.01 mol L(-1) CaCl2 solutions spiked with increasing concentrations of the target PFAS. The sorption reversibility of PFASs was also tested for some of the samples. Liquid chromatography coupled to tandem mass spectrometry was used to quantify the target PFASs in the solutions. Both the Freundlich and linear models were appropriate to describe the sorption behaviour of PFASs in soils, and enabled us to derive solid-liquid distribution coefficients (Kd) for each compound in each soil. Kd values increased from 19 to 295 mL g(-1) for PFOS, from 2.2 to 38 mL g(-1) for PFOA and from 0.4 to 6.8 mL g(-1) for PFBS, and were positively correlated with the organic carbon content of the soil. KOC values obtained from the correlations were 710, 96 and 17 mL g(-1) for PFOS, PFOA and PFBS, respectively. Whereas Kd values decreased in the sequence PFOS>PFOA>PFBS, desorption yields were lower than 13% for PFOS, from 24 to 58% for PFOA, and from 32 to 60% for PFBS. This shows that the physicochemical characteristics of PFASs, basically their hydrophobicity, controlled their sorption behaviour in soils, with PFOS being the most irreversibly sorbed PFAS. Copyright © 2014 Elsevier B.V. All rights reserved.

  4. Modeling Fission Product Sorption in Graphite Structures

    International Nuclear Information System (INIS)

    Szlufarska, Izabela; Morgan, Dane; Allen, Todd

    2013-01-01

    The goal of this project is to determine changes in adsorption and desorption of fission products to/from nuclear-grade graphite in response to a changing chemical environment. First, the project team will employ principle calculations and thermodynamic analysis to predict stability of fission products on graphite in the presence of structural defects commonly observed in very high-temperature reactor (VHTR) graphites. Desorption rates will be determined as a function of partial pressure of oxygen and iodine, relative humidity, and temperature. They will then carry out experimental characterization to determine the statistical distribution of structural features. This structural information will yield distributions of binding sites to be used as an input for a sorption model. Sorption isotherms calculated under this project will contribute to understanding of the physical bases of the source terms that are used in higher-level codes that model fission product transport and retention in graphite. The project will include the following tasks: Perform structural characterization of the VHTR graphite to determine crystallographic phases, defect structures and their distribution, volume fraction of coke, and amount of sp2 versus sp3 bonding. This information will be used as guidance for ab initio modeling and as input for sorptivity models; Perform ab initio calculations of binding energies to determine stability of fission products on the different sorption sites present in nuclear graphite microstructures. The project will use density functional theory (DFT) methods to calculate binding energies in vacuum and in oxidizing environments. The team will also calculate stability of iodine complexes with fission products on graphite sorption sites; Model graphite sorption isotherms to quantify concentration of fission products in graphite. The binding energies will be combined with a Langmuir isotherm statistical model to predict the sorbed concentration of fission products

  5. Ball-milling and AlB2 addition effects on the hydrogen sorption properties of the CaH2 + MgB2 system

    International Nuclear Information System (INIS)

    Schiavo, B.; Girella, A.; Agresti, F.; Capurso, G.; Milanese, C.

    2011-01-01

    Research highlights: → Calcium hydride + magnesium-aluminum borides as candidates for hydrogen storage. → Long time ball milling improves hydrogen sorption kinetics of the CaH 2 +MgB 2 system. → Coexistence of MgB 2 and AlB 2 does not improve hydrogen sorption performances. → Total substitution of MgB 2 with AlB 2 improves the system kinetics and reversibility. → Below 400 deg. C almost the full hydrogen capacity of the CaH 2 + AlB 2 system is reached. - Abstract: Among the borohydrides proposed for solid state hydrogen storage, Ca(BH 4 ) 2 is particularly interesting because of its favourable thermodynamics and relatively cheap price. Composite systems, where other species are present in addition to the borohydride, show some advantages in hydrogen sorption properties with respect to the borohydrides alone, despite a reduction of the theoretical storage capacity. We have investigated the milling time influence on the sorption properties of the CaH 2 + MgB 2 system from which Ca(BH 4 ) 2 and MgH 2 can be synthesized by hydrogen absorption process. Manometric and calorimetric measurements showed better kinetics for long time milled samples. We found that the total substitution of MgB 2 with AlB 2 in the starting material can improve the sorption properties significantly, while the co-existence of both magnesium and aluminum borides in the starting mixture did not cause any improvement. Rietveld refinements of the X-ray powder diffraction spectra were used to confirm the hypothesized reactions.

  6. Cesium sorption from concentrated acidic tank wastes using ammonium molybdophosphate-polyacrylonitrile composite sorbents

    International Nuclear Information System (INIS)

    Todd, T.A.; Mann, N.R.; Tranter, T.J.; Sebesta, F.; John, J.; Motl, A.

    2002-01-01

    Ammonium molybdophosphate-polyacrylonitrile (AMP-PAN) composite sorbents have been evaluated for the removal of cesium from Idaho National Engineering and Environmental Laboratory (INEEL) concentrated acidic tank waste. Batch contacts were performed to qualitatively evaluate the effects of increased nitric acid, sodium and potassium. An equilibrium isotherm was generated with simulated concentrated tank waste solutions and fit to the Langmuir equation. Additional batch contact experiments were performed to determine if mercury, plutonium and americium would sorb onto AMP-PAN. Dynamic sorption was evaluated in column tests employing 1.5 cm 3 columns operating at 5, 10 and 20 bed volumes of flow per hour. Results indicate, as expected, that dynamic cesium sorption capacity is reduced as the flowrate is increased. Calculated dynamic capacities for cesium were 22.5, 19.8 and 19.6 mg Cs/g sorbent, for 5, 10 and 20 bed volume per hour flows, respectively. The thermal stability of loaded AMP-PAN was evaluated by performing thermogravimetric analysis (TGA) on samples of AMP, PAN (polymer), and AMP-PAN. Results indicate that AMP-PAN is stable to 400 deg C, with less than a 10% loss of weight, which is at least partially due to loss of water of hydration. The evaluation of AMP-PAN indicates that it will effectively remove cesium from concentrated acidic tank waste solutions. (author)

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

    Czech Academy of Sciences Publication Activity Database

    Roubíček, Tomáš; Tomassetti, G.

    2014-01-01

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

  8. Magnetization study of UNiSi and its hydride

    Czech Academy of Sciences Publication Activity Database

    Šebek, Josef; Andreev, Alexander V.; Honda, F.; Kolomiets, A. V.; Havela, L.; Sechovský, V.

    2003-01-01

    Roč. 34, č. 2 (2003), s. 1457-1460 ISSN 0587-4254. [International Conference on Strongly Correlated Electron Systems (SCES 02). Cracow, 10.07.2002-13.07.2002] R&D Projects: GA ČR GA202/02/0739 Institutional research plan: CEZ:AV0Z1010914; CEZ:MSM 113200002 Keywords : UNiSi * magnetic measurements * hydride Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.752, year: 2003

  9. Instrinsic defect energies of lithium hydride and lithium deuteride crystals

    International Nuclear Information System (INIS)

    Pandey, R.; Stoneham, A.M.

    1985-01-01

    A theoretical study has been made of the defect structure of lithium hydride and lithium deuteride. A potential model is obtained describing the statics and dynamics of these crystals. Intrinsic defect energies are calculated using the Harwell HADES program which is based on a generalised Mott-Littleton method. The results are in good agreement with the experimental data, and suggest that the vacancy and interstitial migration mechanisms of anions and cations are all comparable in their contribution to ionic conduction. (author)

  10. Equilibrium dissociation pressures of lithium hydride and lithium deuteride

    International Nuclear Information System (INIS)

    Smith, H.M.; Webb, R.E.

    1977-12-01

    The equilibrium dissociation pressures of plateau composition lithium hydride and lithium deuteride have been measured from 450 to 750 0 C. These data were used to derive the relationship of dissociation pressure with temperature over this range and to calculate several thermodynamic properties of these materials. Thermodynamic properties determined included the enthalpy, entropy, and free energy of formation; the enthalpy and entropy of fusion; and the melting points

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

    International Nuclear Information System (INIS)

    Julin, Peng; Bursill, L.A.

    1990-01-01

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

  12. Secondary hydriding of defected zircaloy-clad fuel rods

    International Nuclear Information System (INIS)

    Olander, D.R.; Vaknin, S.

    1993-01-01

    The phenomenon of secondary hydriding in LWR fuel rods is critically reviewed. The current understanding of the process is summarized with emphasis on the sources of hydrogen in the rod provided by chemical reaction of water (steam) introduced via a primary defect in the cladding. As often noted in the literature, the role of hydrogen peroxide produced by steam radiolysis is to provide sources of hydrogen by cladding and fuel oxidation that are absent without fission-fragment irradiation of the gas. Quantitative description of the evolution of the chemical state inside the fuel rod is achieved by combining the chemical kinetics of the reactions between the gas and the fuel and cladding with the transport by diffusion of components of the gas in the gap. The chemistry-gas transport model provides the framework into which therate constants of the reactions between the gases in the gap and the fuel and cladding are incorporated. The output of the model calculation is the H 2 0/H 2 ratio in the gas and the degree of claddingand fuel oxidation as functions of distance from the primary defect. This output, when combined with a criterion for the onset of massive hydriding of the cladding, can provide a prediction of the time and location of a potential secondary hydriding failure. The chemistry-gas transport model is the starting point for mechanical and H-in-Zr migration analyses intended to determine the nature of the cladding failure caused by the development of the massive hydride on the inner wall

  13. SORPTION OF Au(III BY Saccharomyces cerevisiae BIOMASS

    Directory of Open Access Journals (Sweden)

    Amaria Amaria

    2010-07-01

    Full Text Available Au(III sorption by S. cerevisiae biomass extracted from beer waste industry was investigated. Experimentally, the sorption was conducted in batch method. This research involved five steps: 1 identification the functional groups present in the S. cerevisiae biomass by infrared spectroscopic technique, 2 determination of optimum pH, 3 determination of the sorption capacity and energy, 4 determination of the sorption type by conducting desorption of sorbed Au(III using specific eluents having different desorption capacity such as H2O (van der Waals, KNO3 (ion exchange, HNO3 (hydrogen bond, and tiourea (coordination bond, 5 determination of effective eluents in Au(III desorption by partial desorption of sorbed Au(III using thiourea, NaCN and KI. The remaining Au(III concentrations in filtrate were analyzed using Atomic Absorption Spectrophotometer. The results showed that: 1 Functional groups of S. cerevisiae biomass that involved in the sorption processes were hydroxyl (-OH, carboxylate (-COO- and amine (-NH2, 2 maximum sorption was occurred at pH 4, equal to 98.19% of total sorption, 3 The sorption capacity of biomass was 133.33 mg/g (6.7682E-04 mol/g and was involved sorption energy 23.03 kJ mol-1, 4 Sorption type was dominated by coordination bond, 5 NaCN was effective eluent to strip Au(III close to 100%.   Keywords: sorption, desorption, S. cerevisiae biomass, Au(III

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

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Kjell-Tore

    1996-08-01

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

  15. 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)

  16. 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)

  17. First principles characterisation of brittle transgranular fracture of titanium hydrides

    International Nuclear Information System (INIS)

    Olsson, Pär A.T.; Mrovec, Matous; Kroon, Martin

    2016-01-01

    In this work we have studied transgranular cleavage and the fracture toughness of titanium hydrides by means of quantum mechanical calculations based on density functional theory. The calculations show that the surface energy decreases and the unstable stacking fault energy increases with increasing hydrogen content. This is consistent with experimental findings of brittle behaviour of titanium hydrides at low temperatures. Based on Griffith-Irwin theory we estimate the fracture toughness of the hydrides to be of the order of 1 MPa⋅m"1"/"2, which concurs well with experimental data. To investigate the cleavage energetics, we analyse the decohesion at various crystallographic planes and determine the traction-separation laws based on the Rose's extended universal binding energy relation. The calculations predict that the peak stresses do not depend on the hydrogen content of the phases, but it is rather dependent on the crystallographic cleavage direction. However, it is found that the work of fracture decreases with increasing hydrogen content, which is an indication of hydrogen induced bond weakening in the material.

  18. The effect of sample preparation on uranium hydriding

    International Nuclear Information System (INIS)

    Banos, A.; Stitt, C.A.; Scott, T.B.

    2016-01-01

    Highlights: • Distinct differences in uranium hydride growth rates and characteristics between different surface preparation methods. • The primary difference between the categories of sample preparations is the level of strain present in the surface. • Greater surface-strain, leads to higher nucleation number density, implying a preferred attack of strained vs unstrained metal. • As strain is reduced, surface features such as carbides and grain boundaries become more important in controlling the UH3 location. - Abstract: The influence of sample cleaning preparation on the early stages of uranium hydriding has been examined, by using four identical samples but concurrently prepared using four different methods. The samples were reacted together in the same corrosion cell to ensure identical exposure conditions. From the analysis, it was found that the hydride nucleation rate was proportional to the level of strain exhibiting higher number density for the more strained surfaces. Additionally, microstructure of the metal plays a secondary role regarding initial hydrogen attack on the highly strained surfaces yet starts to dominate the system while moving to more pristine samples.

  19. Metal hydride-based thermal energy storage systems

    Science.gov (United States)

    Vajo, John J.; Fang, Zhigang

    2017-10-03

    The invention provides a thermal energy storage system comprising a metal-containing first material with a thermal energy storage density of about 1300 kJ/kg to about 2200 kJ/kg based on hydrogenation; a metal-containing second material with a thermal energy storage density of about 200 kJ/kg to about 1000 kJ/kg based on hydrogenation; and a hydrogen conduit for reversibly transporting hydrogen between the first material and the second material. At a temperature of 20.degree. C. and in 1 hour, at least 90% of the metal is converted to the hydride. At a temperature of 0.degree. C. and in 1 hour, at least 90% of the metal hydride is converted to the metal and hydrogen. The disclosed metal hydride materials have a combination of thermodynamic energy storage densities and kinetic power capabilities that previously have not been demonstrated. This performance enables practical use of thermal energy storage systems for electric vehicle heating and cooling.

  20. A thermal neutron scattering law for yttrium hydride

    Science.gov (United States)

    Zerkle, Michael; Holmes, Jesse

    2017-09-01

    Yttrium hydride (YH2) is of interest as a high temperature moderator material because of its superior ability to retain hydrogen at elevated temperatures. Thermal neutron scattering laws for hydrogen bound in yttrium hydride (H-YH2) and yttrium bound in yttrium hydride (Y-YH2) prepared using the ab initio approach are presented. Density functional theory, incorporating the generalized gradient approximation (GGA) for the exchange-correlation energy, is used to simulate the face-centered cubic structure of YH2 and calculate the interatomic Hellmann-Feynman forces for a 2 × 2 × 2 supercell containing 96 atoms. Lattice dynamics calculations using PHONON are then used to determine the phonon dispersion relations and density of states. The calculated phonon density of states for H and Y in YH2 are used to prepare H-YH2 and Y-YH2 thermal scattering laws using the LEAPR module of NJOY2012. Analysis of the resulting integral and differential scattering cross sections demonstrates adequate resolution of the S(α,β) function. Comparison of experimental lattice constant, heat capacity, inelastic neutron scattering spectra and total scattering cross section measurements to calculated values are used to validate the thermal scattering laws.

  1. Evaluation of Neutron shielding efficiency of Metal hydrides

    Energy Technology Data Exchange (ETDEWEB)

    Jeon, Sang Hwan; Chae, San; Kim, Yong Soo [Hanyang University, Seoul (Korea, Republic of)

    2012-05-15

    Neutron shielding is achieved of interaction with material by moderation and absorption. Material that contains large amounts hydrogen atoms which are almost same neutron atomic weight is suited for fast neutron shielding material. Therefore, polymers containing high density hydrogen atom are being used for fast neutron shielding. On the other hand, composite materials containing high thermal neutron absorption cross section atom (Li, B, etc) are being used for thermal neutron shielding. However, these materials have low fast neutron absorption cross section. Therefore, these materials are not suited for fast neutron shielding. Hydrogen which has outstanding neutron energy reduction ability has very low thermal neutron absorption cross section, almost cannot be used for thermal neutron shielding. In this case, a large atomic number material (Pb, U, etc.) has been used. Thus, metal hydrides are considered as complement to concrete shielding material. Because metal hydrides contain high hydrogen density and elements with high atomic number. In this research neutron shielding performance and characteristic of nuclear about metal hydrides ((TiH{sub 2}, ZrH{sub 2}, HfH{sub 2}) is evaluated by experiment and MCNPX using {sup 252}Cf neutron source as purpose development shielding material to developed shielding material

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

    International Nuclear Information System (INIS)

    Botzung, Maxime; Chaudourne, Serge; Perret, Christian; Latroche, Michel; Percheron-Guegan, Annick; Marty Philippe

    2006-01-01

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

  3. Oxidation kinetics of hydride-bearing uranium metal corrosion products

    Science.gov (United States)

    Totemeier, Terry C.; Pahl, Robert G.; Frank, Steven M.

    The oxidation behavior of hydride-bearing uranium metal corrosion products from Zero Power Physics Reactor (ZPPR) fuel plates was studied using thermo-gravimetric analysis (TGA) in environments of Ar-4%O 2, Ar-9%O 2, and Ar-20%O 2. Ignition of corrosion product samples from two moderately corroded plates was observed between 125°C and 150°C in all environments. The rate of oxidation above the ignition temperature was found to be dependent only on the net flow rate of oxygen in the reacting gas. Due to the higher net oxygen flow rate, burning rates increased with increasing oxygen concentration. Oxidation rates below the ignition temperature were much slower and decreased with increasing test time. The hydride contents of the TGA samples from the two moderately corroded plates, determined from the total weight gain achieved during burning, were 47-61 wt% and 29-39 wt%. Samples from a lightly corroded plate were not reactive; X-ray diffraction (XRD) confirmed that they contained little hydride.

  4. Oxidation kinetics of hydride-bearing uranium metal corrosion products

    International Nuclear Information System (INIS)

    Totemeier, T.C.; Pahl, R.G.; Frank, S.M.

    1998-01-01

    The oxidation behavior of hydride-bearing uranium metal corrosion products from zero power physics reactor (ZPPR) fuel plates was studied using thermo-gravimetric analysis (TGA) in environments of Ar-4%O 2 , Ar-9%O 2 , and Ar-20%O 2 . Ignition of corrosion product samples from two moderately corroded plates was observed between 125 C and 150 C in all environments. The rate of oxidation above the ignition temperature was found to be dependent only on the net flow rate of oxygen in the reacting gas. Due to the higher net oxygen flow rate, burning rates increased with increasing oxygen concentration. Oxidation rates below the ignition temperature were much slower and decreased with increasing test time. The hydride contents of the TGA samples from the two moderately corroded plates, determined from the total weight gain achieved during burning, were 47-61 wt% and 29-39 wt%. Samples from a lightly corroded plate were not reactive; X-ray diffraction (XRD) confirmed that they contained little hydride. (orig.)

  5. Performance study of a hydrogen powered metal hydride actuator

    International Nuclear Information System (INIS)

    Bhuiya, Md Mainul Hossain; Kim, Kwang J

    2016-01-01

    A thermally driven hydrogen powered actuator integrating metal hydride hydrogen storage reactor, which is compact, noiseless, and able to generate smooth actuation, is presented in this article. To test the plausibility of a thermally driven actuator, a conventional piston type actuator was integrated with LaNi 5 based hydrogen storage system. Copper encapsulation followed by compaction of particles into pellets, were adopted to improve overall thermal conductivity of the reactor. The operation of the actuator was thoroughly investigated for an array of operating temperature ranges. Temperature swing of the hydride reactor triggering smooth and noiseless actuation over several operating temperature ranges were monitored for quantification of actuator efficiency. Overall, the actuator generated smooth and consistent strokes during repeated cycles of operation. The efficiency of the actuator was found to be as high as 13.36% for operating a temperature range of 20 °C–50 °C. Stress–strain characteristics, actuation hysteresis etc were studied experimentally. Comparison of stress–strain characteristics of the proposed actuator with traditional actuators, artificial muscles and so on was made. The study suggests that design modification and use of high pressure hydride may enhance the performance and broaden the application horizon of the proposed actuator in future. (paper)

  6. Pebble-bed reactor

    International Nuclear Information System (INIS)

    Lohnert, G.; Mueller-Frank, U.; Heil, J.

    1976-01-01

    A pebble-bed nuclear reactor of large power rating comprises a container having a funnel-shaped bottom forming a pebble run-out having a centrally positioned outlet. A bed of downwardly-flowing substantially spherical nuclear fuel pebbles is positioned in the container and forms a reactive nuclear core maintained by feeding unused pebbles to the bed's top surface while used or burned-out pebbles run out and discharge through the outlet. A substantially conical body with its apex pointing upwardly and its periphery spaced from the periphery of the container spreads the bottom of the bed outwardly to provide an annular flow down the funnel-shaped bottom forming the runout, to the discharge outlet. This provides a largely constant downward velocity of the spheres throughout the diameter of the bed throughout a substantial portion of the down travel, so that all spheres reach about the same burned-out condition when they leave the core, after a single pass through the core area

  7. Fluidised bed heat exchangers

    International Nuclear Information System (INIS)

    Elliott, D.E.; Healey, E.M.; Roberts, A.G.

    1974-01-01

    Problems that have arisen during the initial stages of development of fluidised bed boilers in which heat transfer surfaces are immersed in fluidised solids are discussed. The very high heat transfer coefficients that are obtained under these conditions can be exploited to reduce the total heat transfer surface to a fraction of that in normal boilers. However, with the high heat flux levels involved, tube stressing becomes more important and it is advantageous to use smaller diameter tubes. One of the initial problems was that the pumping power absorbed by the fluidised bed appeared to be high. The relative influence of the fluidising velocity (and the corresponding bed area), tube diameter, tube spacing, heat transfer coefficient and bed temperature on pumping power and overall cost was determined. This showed the importance of close tube packing and research was undertaken to see if this would adversely affect the heat transfer coefficient. Pressure operation also reduces the pumping power. Fouling and corrosion tests in beds burning coal suggest that higher temperatures could be reached reliably and cost studies show that, provided the better refractory metals are used, the cost of achieving higher temperatures is not unduly high. It now remains to demonstrate at large scale that the proposed systems are viable and that the methods incorporated to overcome start up and part lead running problems are satisfactory. The promising role of these heat transfer techniques in other applications is briefly discussed

  8. Thermodynamic sorption modelling in support of radioactive waste disposal safety cases - NEA sorption project phase III

    International Nuclear Information System (INIS)

    2012-01-01

    A central safety function of radioactive waste disposal repositories is the prevention or sufficient retardation of radionuclide migration to the biosphere. Performance assessment exercises in various countries, and for a range of disposal scenarios, have demonstrated that one of the most important processes providing this safety function is the sorption of radionuclides along potential migration paths beyond the engineered barriers. Thermodynamic sorption models (TSMs) are key for improving confidence in assumptions made about such radionuclide sorption when preparing a repository's safety case. This report presents guidelines for TSM development as well as their application in repository performance assessments. They will be of particular interest to the sorption modelling community and radionuclide migration modellers in developing safety cases for radioactive waste disposal Contents: 1 - Thermodynamic sorption models and radionuclide migration: Sorption and radionuclide migration; Applications of TSMs in radioactive waste disposal studies; Requirements for a scientifically defensible, calibrated TSM applicable to radioactive waste disposal; Current status of TSMs in radioactive waste management; 2 - Theoretical basis of TSMs and options in model development: Conceptual building blocks of TSMs and integration with aqueous chemistry; The TSM representation of sorption and relationship with Kd values; Theoretical basis of TSMs; Example of TSM for uranyl sorption; Options in TSM development; Illustration of TSM development and effects of modelling choices; Summary: TSMs for constraining Kd values - impact of modelling choices; 3 - Determination of parameters for TSMs: Overview of experimental determination of TSM parameters; Theoretical estimation methods of selected model parameters; Case study: sorption modelling of trivalent lanthanides/actinides on illite; Indicative values for certain TSM parameters; Parameter uncertainty; Illustration of parameter sensitivity

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

    International Nuclear Information System (INIS)

    Ramanathan, L.V.

    1983-01-01

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

  10. Zirconium hydrides and Fe redistribution in Zr-2.5%Nb alloy under ion irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Idrees, Y.; Yao, Z. [Department of Mechanical and Materials Engineering, Queen' s University, Kingston, ON, Canada, K7L 3N6 (Canada); Cui, J.; Shek, G.K. [Kinetrics, Mississauga, ON (Canada); Daymond, M.R., E-mail: daymond@queensu.ca [Department of Mechanical and Materials Engineering, Queen' s University, Kingston, ON, Canada, K7L 3N6 (Canada)

    2016-11-15

    Zr-2.5%Nb alloy is used to fabricate the pressure tubes of the CANDU reactor. The pressure tube is the primary pressure boundary for coolant in the CANDU design and is susceptible to delayed hydride cracking, reduction in fracture toughness upon hydride precipitation and potentially hydride blister formation. The morphology and nature of hydrides in Zr-2.5%Nb with 100 wppm hydrogen has been investigated using transmission electron microscopy. The effect of hydrides on heavy ion irradiation induced decomposition of the β phase has been reported. STEM-EDX mapping was employed to investigate the distribution of alloying elements. The results show that hydrides are present in the form of stacks of different sizes, with length scales from nano- to micro-meters. Heavy ion irradiation experiments at 250 °C on as-received and hydrided Zr-2.5%Nb alloy, show interesting effects of hydrogen on the irradiation induced redistribution of Fe. It was found that Fe is widely redistributed from the β phase into the α phase in the as-received material, however, the loss of Fe from the β phase and subsequent precipitation is retarded in the hydrided material. This preliminary work will further the current understanding of microstructural evolution of Zr based alloys in the presence of hydrogen. - Graphical abstract: STEM HAADF micrographs at low magnification showing the hydride structure in Zr-2.5Nb alloy.

  11. Hydrogen storage and evolution catalysed by metal hydride complexes.

    Science.gov (United States)

    Fukuzumi, Shunichi; Suenobu, Tomoyoshi

    2013-01-07

    The storage and evolution of hydrogen are catalysed by appropriate metal hydride complexes. Hydrogenation of carbon dioxide by hydrogen is catalysed by a [C,N] cyclometalated organoiridium complex, [Ir(III)(Cp*)(4-(1H-pyrazol-1-yl-κN(2))benzoic acid-κC(3))(OH(2))](2)SO(4) [Ir-OH(2)](2)SO(4), under atmospheric pressure of H(2) and CO(2) in weakly basic water (pH 7.5) at room temperature. The reverse reaction, i.e., hydrogen evolution from formate, is also catalysed by [Ir-OH(2)](+) in acidic water (pH 2.8) at room temperature. Thus, interconversion between hydrogen and formic acid in water at ambient temperature and pressure has been achieved by using [Ir-OH(2)](+) as an efficient catalyst in both directions depending on pH. The Ir complex [Ir-OH(2)](+) also catalyses regioselective hydrogenation of the oxidised form of β-nicotinamide adenine dinucleotide (NAD(+)) to produce the 1,4-reduced form (NADH) under atmospheric pressure of H(2) at room temperature in weakly basic water. In weakly acidic water, the complex [Ir-OH(2)](+) also catalyses the reverse reaction, i.e., hydrogen evolution from NADH to produce NAD(+) at room temperature. Thus, interconversion between NADH (and H(+)) and NAD(+) (and H(2)) has also been achieved by using [Ir-OH(2)](+) as an efficient catalyst and by changing pH. The iridium hydride complex formed by the reduction of [Ir-OH(2)](+) by H(2) and NADH is responsible for the hydrogen evolution. Photoirradiation (λ > 330 nm) of an aqueous solution of the Ir-hydride complex produced by the reduction of [Ir-OH(2)](+) with alcohols resulted in the quantitative conversion to a unique [C,C] cyclometalated Ir-hydride complex, which can catalyse hydrogen evolution from alcohols in a basic aqueous solution (pH 11.9). The catalytic mechanisms of the hydrogen storage and evolution are discussed by focusing on the reactivity of Ir-hydride complexes.

  12. Reactivity patterns of transition metal hydrides and alkyls

    International Nuclear Information System (INIS)

    Jones, W.D. II.

    1979-05-01

    The complex PPN + CpV(CO) 3 H - (Cp=eta 5 -C 5 H 5 and PPN = (Ph 3 P) 2 ) was prepared in 70% yield and its physical properties and chemical reactions investigated. PPN + CpV(CO) 3 H - reacts with a wide range of organic halides. The organometallic products of these reactions are the vanadium halides PPN + [CpV(C) 3 X] - and in some cases the binuclear bridging hydride PPN + [CpV(CO) 3 ] 2 H - . The borohydride salt PPN + [CpV(CO) 3 BH 4 ] - has also been prepared. The reaction between CpV(CO) 3 H - and organic halides was investigated and compared with halide reductions carried out using tri-n-butyltin hydride. Results demonstrate that in almost all cases, the reduction reaction proceeds via free radical intermediates which are generated in a chain process, and are trapped by hydrogen transfer from CpV(CO) 3 H - . Sodium amalgam reduction of CpRh(CO) 2 or a mixture of CpRh(CO) 2 and CpCo(CO) 2 affords two new anions, PPN + [Cp 2 Rh 3 (CO) 4 ] - and PPN + [Cp 2 RhCo(CO) 2 ] - . CpMo(CO) 3 H reacts with CpMo(CO) 3 R (R=CH 3 ,C 2 H 5 , CH 2 C 6 H 5 ) at 25 to 50 0 C to produce aldehyde RCHO and the dimers [CpMo(CO) 3 ] 2 and [CpMo(CO) 2 ] 2 . In general, CpV(CO) 3 H - appears to transfer a hydrogen atom to the metal radical anion formed in an electron transfer process, whereas CpMo(CO) 3 H transfers hydride in a 2-electron process to a vacant coordination site. The chemical consequences are that CpV(CO) 3 H - generally reacts with metal alkyls to give alkanes via intermediate alkyl hydride species whereas CpMo(CO) 3 H reacts with metal alkyls to produce aldehyde, via an intermediate acyl hydride species

  13. Reactivity patterns of transition metal hydrides and alkyls

    Energy Technology Data Exchange (ETDEWEB)

    Jones, W.D. II

    1979-05-01

    The complex PPN/sup +/ CpV(CO)/sub 3/H/sup -/ (Cp=eta/sup 5/-C/sub 5/H/sub 5/ and PPN = (Ph/sub 3/P)/sub 2/) was prepared in 70% yield and its physical properties and chemical reactions investigated. PPN/sup +/ CpV(CO)/sub 3/H/sup -/ reacts with a wide range of organic halides. The organometallic products of these reactions are the vanadium halides PPN/sup +/(CpV(C)/sub 3/X)/sup -/ and in some cases the binuclear bridging hydride PPN/sup +/ (CpV(CO)/sub 3/)/sub 2/H/sup -/. The borohydride salt PPN/sup +/(CpV(CO)/sub 3/BH/sub 4/)/sup -/ has also been prepared. The reaction between CpV(CO)/sub 3/H/sup -/ and organic halides was investigated and compared with halide reductions carried out using tri-n-butyltin hydride. Results demonstrate that in almost all cases, the reduction reaction proceeds via free radical intermediates which are generated in a chain process, and are trapped by hydrogen transfer from CpV(CO)/sub 3/H/sup -/. Sodium amalgam reduction of CpRh(CO)/sub 2/ or a mixture of CpRh(CO)/sub 2/ and CpCo(CO)/sub 2/ affords two new anions, PPN/sup +/ (Cp/sub 2/Rh/sub 3/(CO)/sub 4/)/sup -/ and PPN/sup +/(Cp/sub 2/RhCo(CO)/sub 2/)/sup -/. CpMo(CO)/sub 3/H reacts with CpMo(CO)/sub 3/R (R=CH/sub 3/,C/sub 2/H/sub 5/, CH/sub 2/C/sub 6/H/sub 5/) at 25 to 50/sup 0/C to produce aldehyde RCHO and the dimers (CpMo(CO)/sub 3/)/sub 2/ and (CpMo(CO)/sub 2/)/sub 2/. In general, CpV(CO)/sub 3/H/sup -/ appears to transfer a hydrogen atom to the metal radical anion formed in an electron transfer process, whereas CpMo(CO)/sub 3/H transfers hydride in a 2-electron process to a vacant coordination site. The chemical consequences are that CpV(CO)/sub 3/H/sup -/ generally reacts with metal alkyls to give alkanes via intermediate alkyl hydride species whereas CpMo(CO)/sub 3/H reacts with metal alkyls to produce aldehyde, via an intermediate acyl hydride species.

  14. Defluoridation by Bacteriogenic Iron Oxides: Sorption Studies

    Science.gov (United States)

    Evans, K.; Ferris, F.

    2009-05-01

    At concentrations above 1 mg/L, fluoride in drinking water can lead to dental and skeletal fluorosis, a disease that causes mottling of the teeth, calcification of ligaments, crippling bone deformities and many other physiological disorders that can, ultimately, lead to death. Conservative estimates are that fluorosis afflicts tens of millions of people worldwide. As there is no treatment for fluorosis, prevention is the only means of controlling the disease. While numerous defluoridation techniques have been explored, no single method has been found to be both effective and inexpensive enough to implement widely. Our research began in India, with a large-scale geochemical study of the groundwater in a fluoride-contaminated region of Orissa. Having developed a better understanding of the geochemical relationships that exist between fluoride and other parameters present in an affected area, as well as the complex relationships that arise among those parameters that can impact the presence of fluoride, we began investigating certain remediation scenarios involving iron oxides. A common approach to remediation involves the partitioning of fluoride from groundwater by sorption onto a variety of materials, one of the most effective of which is iron oxide whose surface area acts as a scavenger for fluoride. In the presence of iron oxidizing bacteria, the oxidation rate of iron has been shown to be ˜6 times greater than in their absence; fluoride should, therefore, be removed from an aqueous environment by bacteriogenic iron oxides (BIOS) much more quickly than by abiotic iron oxides. Most recently, sorption studies have been conducted using both BIOS and synthetic hydrous ferric oxides in order to compare the behavior between biotic and abiotic sorbents. These studies have provided sorption isotherms that allow comparison of fluoride removed by sorption to BIOS versus synthetic iron oxides. Sorption affinity constants have also been determined, which allow for the

  15. The Safety of Hospital Beds

    Science.gov (United States)

    Gervais, Pierre; Pooler, Charlotte; Merryweather, Andrew; Doig, Alexa K.; Bloswick, Donald

    2015-01-01

    To explore the safety of the standard and the low hospital bed, we report on a microanalysis of 15 patients’ ability to ingress, move about the bed, and egress. The 15 participants were purposefully selected with various disabilities. Bed conditions were randomized with side rails up or down and one low bed with side rails down. We explored the patients’ use of the side rails, bed height, ability to lift their legs onto the mattress, and ability to turn, egress, and walk back to the chair. The standard bed was too high for some participants, both for ingress and egress. Side rails were used by most participants when entering, turning in bed, and exiting. We recommend that side rails be reconsidered as a means to facilitate in-bed movement, ingress, and egress. Furthermore, single deck height settings for all patients are not optimal. Low beds as a safety measure must be re-evaluated. PMID:28462302

  16. Isotherm, kinetic, and thermodynamic study of ciprofloxacin sorption on sediments.

    Science.gov (United States)

    Mutavdžić Pavlović, Dragana; Ćurković, Lidija; Grčić, Ivana; Šimić, Iva; Župan, Josip

    2017-04-01

    In this study, equilibrium isotherms, kinetics and thermodynamics of ciprofloxacin on seven sediments in a batch sorption process were examined. The effects of contact time, initial ciprofloxacin concentration, temperature and ionic strength on the sorption process were studied. The K d parameter from linear sorption model was determined by linear regression analysis, while the Freundlich and Dubinin-Radushkevich (D-R) sorption models were applied to describe the equilibrium isotherms by linear and nonlinear methods. The estimated K d values varied from 171 to 37,347 mL/g. The obtained values of E (free energy estimated from D-R isotherm model) were between 3.51 and 8.64 kJ/mol, which indicated a physical nature of ciprofloxacin sorption on studied sediments. According to obtained n values as measure of intensity of sorption estimate from Freundlich isotherm model (from 0.69 to 1.442), ciprofloxacin sorption on sediments can be categorized from poor to moderately difficult sorption characteristics. Kinetics data were best fitted by the pseudo-second-order model (R 2  > 0.999). Thermodynamic parameters including the Gibbs free energy (ΔG°), enthalpy (ΔH°) and entropy (ΔS°) were calculated to estimate the nature of ciprofloxacin sorption. Results suggested that sorption on sediments was a spontaneous exothermic process.

  17. Testosterone sorption and desorption: Effects of soil particle size

    Energy Technology Data Exchange (ETDEWEB)

    Qi, Yong, E-mail: yqi01@unomaha.edu [Civil Engineering Dept., University of Nebraska-Lincoln at Omaha Campus, Omaha, NE 68182 (United States); Zhang, Tian C. [Civil Engineering Dept., University of Nebraska-Lincoln at Omaha Campus, Omaha, NE 68182 (United States); Ren, Yongzheng [School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2014-08-30

    Graphical abstract: - Highlights: • Smaller soil particles have higher sorption and lower desorption rates. • The sorption capacity ranks as clay > silt > sand. • Small particles like clays have less potential for desorption. • Colloids (clays) have high potential to facilitate the transport of hormones in soil–water environments. - Abstract: Soils contain a wide range of particles of different diameters with different mobility during rainfall events. Effects of soil particles on sorption and desorption behaviors of steroid hormones have not been investigated. In this study, wet sieve washing and repeated sedimentation methods were used to fractionate the soils into five ranges. The sorption and desorption properties and related mechanisms of testosterone in batch reactors filled with fractionated soil particles were evaluated. Results of sorption and desorption kinetics indicate that small soil particles have higher sorption and lower desorption rates than that of big ones. Thermodynamic results show the sorption processes are spontaneous and exothermal. The sorption capacity ranks as clay > silt > sand, depending mainly on specific surface area and surface functional groups. The urea control test shows that hydrogen bonding contributes to testosterone sorption onto clay and silt but not on sand. Desorption tests indicate sorption is 36–65% irreversible from clay to sand. Clays have highest desorption hysteresis among these five soil fractions, indicating small particles like clays have less potential for desorption. The results provide indirect evidence on the colloid (clay)-facilitated transport of hormones (micro-pollutants) in soil environments.

  18. Effect of natural organic materials on cadmium and neptunium sorption

    International Nuclear Information System (INIS)

    Kung, K.S.; Triay, I.R.

    1994-01-01

    In a batch sorption study of the effect of naturally occurring organic materials on the sorption of cadmium and neptunium on oxides and tuff surfaces, the model sorbents were synthetic goethite, boehmite, amorphous silicon oxides, and a crushed tuff material from Yucca Mountain, Nevada. An amino acid, 3-(3,4-dihydroxypheny)-DL-alanine (DOPA), and an aquatic-originated fulvic material, Nordic aquatic fulvic acid (NAFA), were used as model organic chemicals. Sorption isotherm results showed that DOPA sorption followed the order aluminum oxide > iron oxide > silicon oxide and that the amount of DOAP sorption for a given sorbent increased as the solution pH was raised. The sorption of cadmium and neptunium on the iron oxide was about ten times higher than that on the aluminum oxide. The sorption of cadmium and neptunium on natural tuff material was much lower than that on aluminum and iron oxides. The sorption of cadmium on iron and aluminum oxides was found to be influenced by the presence of DOPA, and increasing the amount of DOPA coating resulted in higher cadmium sorption on aluminum oxide. However, for iron oxide, cadmium sorption decreased with increasing DOPA concentration. The presence of the model organic materials DOPA and NAFA did not affect the sorption of neptunium on tuff material or on the iron and aluminum oxides. Spectroscopic results indicate that cadmium complexes strongly with DOPA. Therefore, the effect of the organic material, DOPA, on the cadmium sorption is readily observed. However, neptunium is possibly complexed weakly with organic material. Thus, DOPA and NAFA have little effect on neptunium sorption on all sorbents selected for study

  19. Sorption of actinides in granitic rock

    International Nuclear Information System (INIS)

    Allard, B

    1982-11-01

    The sorption of americium (III), neptunium(V) and plutonium on geologic media under oxic conditions has been measured by a batch technique. The aqueous phase was a synthetic groundwater or 4M NaCl solution. The solid phase was a pure mineral, representative of igneous rocks, or granite. Altogether 40 different minerals and rocks were used. The effects of pH and the ionic strength of the aqueous phase as well as of the cation exchange capacity and the surface/mass ratio of the solid sorbent are discussed. Empirical equations giving the distribution coefficient as a function of pH in the environmental pH-range 7-9 are suggested. Some observations and conclusions concerning sorption mechanisms are given. (author)

  20. Sorption analyses in materials science: selected oxides

    International Nuclear Information System (INIS)

    Fuller, E.L. Jr.; Condon, J.B.; Eager, M.H.; Jones, L.L.

    1981-01-01

    Physical adsorption studies have been shown to be extremely valuable in studying the chemistry and structure of dispersed materials. Many processes rely on the access to the large amount of surface made available by the high degree of dispersion. Conversely, there are many applications where consolidation of the dispersed solids is required. Several systems (silica gel, alumina catalysts, mineralogic alumino-silicates, and yttrium oxide plasters) have been studied to show the type and amount of chemical and structural information that can be obtained. Some review of current theories is given and additional concepts are developed based on statistical and thermodynamic arguments. The results are applied to sorption data to show that detailed sorption analyses are extremely useful and can provide valuable information that is difficult to obtain by any other means. Considerable emphasis has been placed on data analyses and interpretation of a nonclassical nature to show the potential of such studies that is often not recognized nor utilized

  1. Sorption of zinc on human teeth

    International Nuclear Information System (INIS)

    Helal, A.; Amin, H.; Alian, G.

    1997-01-01

    Zinc containing dental amalgams are sometimes used as fillings by dentists. The freshly mixed mass of the amalgam alloy and liquid mercury packed or condensed into a prepared tooth cavity. Zinc has been included in amalgams alloys up to 2% as an aid in manufacturing by helping to produce clean sound castings of the ingots. Although such restorations have a relatively long service life, they are subject to corrosion and galvanic action, thus releasing metallic products into the oral environment. The aim of this paper is to investigate the uptake (sorption) of Zinc ionic species on human teeth using the radioactive tracer technique. For this purpose the isotope Zn-65 produced from pile-irradiation of zinc metal was used. The various liquids studied were drinking water (tap water), tea, coffee, red tea and chicken soup. Sorption was studied through immersion of a single human tooth (extracted) in each of these liquids

  2. Sorption of 60 Co on inorganic solids

    International Nuclear Information System (INIS)

    Granados C, F.; Bulbulian G, S.; Mardel V, B.

    2003-01-01

    The behavior of sorption of the 60 Co in aqueous solution under static conditions to different values of pH of the aqueous solution (1, 3, 5, 7, and 10) on MgO, MnO 2 , SnO, TiO 2 , activated carbon and calcinate hydrotalcite was investigated. It was found that the best sorbents of the 60 Co was the MnO 2 , activated carbon and TiO 2 whose sorption was incremented when increasing the pH value of the aqueous solutions, in the one case of the hydrated oxides, the 60 Co interacted with the electrically charged surface of the sorbents that depends on the pH of the solution and of the point of zero charge (zpc) of the sorbent. (Author)

  3. Noble metal extraction and sorption concentrating

    International Nuclear Information System (INIS)

    Petrukhin, O.M.; Malofeeva, G.I.

    1985-01-01

    Works performed in the USSR Academy of Sciences GEOCHI laboratory of extraction methods and devoted to selectivity problems of extraction and sorption methods of platinum metal, cadmium and indium concentrating in analytical chemistry are discussed. On choosing complexino. reagent main attention is paid to the selectivity variation based on different stability of metal complexes. Platinum metals are extracted in the form of ion associates when usinq hard, mainly oxyqen-containing, extractants. Coordination-solvated metal complexes are extracted white usinq extractants containing sulfur, trivalent phosphorus and aromatic nitroqen as donor anions. Selectivity is maximum for sulfur- and nitroren-containinq extractants and sorbents. In case of the group extraction of platinum metals sorption is preferable and in case of selective extraction of individual metals, especially, in case of need of relative concentratinq extraction is preferable

  4. Uranium sorption on tezontle volcanic rock

    International Nuclear Information System (INIS)

    Lopez M, B. E.; Duran B, J. M.; Iturbe G, J. L.; Olguin G, M. T.

    2009-01-01

    It is described a study that demonstrates that hexavalent uranium ions were sorbed by the naturally occurring mineral using a batch technique. This mineral is found in abundant quantities in Mexico. Our study focused on the separation of U Vi from synthetic aqueous systems of both H 2 O-UO 2 (NO 3 ) 2 .6H 2 O (acid) and H 2 O-Na 4 [UO 2 (CO 3 ) 3 ] (basic). The chemical speciation was performed by using high voltage electrophoresis, and the uranium content was determined by UV-Vis spectroscopy. The quantified U(Vi) sorption by tezontle from acidic and basic systems was 2.72 and 1.68 μmol/g, respectively, and the sorption behavior is discussed considering the surface charge of the tezontle at different ph values based on the point of zero charge characteristic of this material. (Author)

  5. Sorption of phenanthrene on agricultural soils

    DEFF Research Database (Denmark)

    Soares, Antonio; Møldrup, Per; Minh, Luong Nhat

    2013-01-01

    Polyaromatic hydrocarbon (PAH) sorption to soil is a key process deciding the transport and fate of PAH, and potential toxic impacts in the soil and groundwater ecosystems, for example in connection with atmospheric PAH deposition on soils. There are numerous studies on PAH sorption in relatively......, 0.25–1-m depth) by the single-point adsorption method. The organic carbon partition coefficient, KOC (liter per kilogram) for topsoils was found generally to fall between the KOC values estimated by the two most frequently used models for PAH partitioning, the Abdul et al. (Hazardous Waste...... & Hazardous Materials 4(3):211–222, 1987) model and Karickhoff et al. (Water Research 13:241–248, 1979) model. A less-recognized model by Karickhoff (Chemosphere 10:833–846, 1981), yielding a KOC of 14,918 L kg−1, closely corresponded to the average measured KOC value for the topsoils, and this model...

  6. Sorption of radionuclides on London clay

    International Nuclear Information System (INIS)

    Berry, J.A.; Bourke, P.J.; Green, A.; Littleboy, A.K.

    1989-02-01

    Techniques for studying the sorption of radionuclides on London clay have been investigated. This work involved the use of through-diffusion, in-diffusion, high-pressure convection and batch methods to study the sorption of iodide, strontium, caesium and americium. Through-diffusion and high-pressure convection methods were found to be most useful for investigating weakly and moderately sorbing nuclides and give realistic values for sorptivity. The batch technique remains the most practical method of obtaining large quantities of data within a relatively short timescale but gives very high sorptivity values. It is however very useful for intercomparisons of nuclides or geological media. The in-diffusion method requires further refinement for use with strongly sorbing nuclides. Good agreement between through-diffusion and high-pressure convection methods was obtained for the sorptivity of strontium, whilst trends observed for caesium by through-diffusion were confirmed by batch measurements. (author)

  7. Positron Spectroscopy of Nanodiamonds after Hydrogen Sorption

    Directory of Open Access Journals (Sweden)

    Lyudmila Nikitina

    2018-01-01

    Full Text Available The structure and defects of nanodiamonds influence the hydrogen sorption capacity. Positronium can be used as a sensor for detecting places with the most efficient capture of hydrogen atoms. Hydrogenation of carbon materials was performed from gas atmosphere. The concentration of hydrogen absorbed by the sample depends on the temperature and pressure. The concentration 1.2 wt % is achieved at the temperature of 243 K and the pressure of 0.6 MPa. The hydrogen saturation of nanodiamonds changes the positron lifetime. Increase of sorption cycle numbers effects the positron lifetime, as well as the parameters of the Doppler broadening of annihilation line. The electron-positron annihilation being a sensitive method, it allows detecting the electron density fluctuation of the carbon material after hydrogen saturation.

  8. Sorption studies of radioelements on geological materials

    International Nuclear Information System (INIS)

    Berry, John A.; Yui, Mikazu; Kitamura, Akira

    2007-11-01

    Batch sorption experiments have been carried out to study the sorption of uranium, technetium, curium, neptunium, actinium, protactinium, polonium, americium and plutonium onto bentonite, granodiorite and tuff. Mathematical modelling using the HARPHRQ program and the HATCHES database was carried out to predict the speciation of uranium and technetium in the equilibrated seawater, and neptunium, americium and plutonium in the rock equilibrated water. Review of the literature for thermodynamic data for curium, actinium, protactinium and polonium was carried out. Where sufficient data were available, predictions of the speciation and solubility were made. This report is a summary report of the experimental work conducted by AEA Technology during April 1991-March 1998, and the main results have been presented at Material Research Society Symposium Proceedings and published as proceedings of them. (author)

  9. Apparatus for controlling fluidized beds

    Science.gov (United States)

    Rehmat, A.G.; Patel, J.G.

    1987-05-12

    An apparatus and process are disclosed for control and maintenance of fluidized beds under non-steady state conditions. An ash removal conduit is provided for removing solid particulates from a fluidized bed separate from an ash discharge conduit in the lower portion of the grate supporting such a bed. The apparatus and process of this invention is particularly suitable for use in ash agglomerating fluidized beds and provides control of the fluidized bed before ash agglomeration is initiated and during upset conditions resulting in stable, sinter-free fluidized bed maintenance. 2 figs.

  10. Understanding hydride formation in Zr-1Nb alloy through microstructural characterization

    International Nuclear Information System (INIS)

    Neogy, S.; Srivastava, D.; Tewari, R.; Singh, R.N.; Dey, G.K.; De, P.K.; Banerjee, S.

    2003-07-01

    In this study the experimental results of hydride formation and their microstructure evolution in Zr-1Nb alloy is presented. This Zr-1Nb binary alloy and other Zr-1 Nb based ternary and quaternary alloys are being used as fuel tube materials and have the potential for meeting the requirement of high burn up fuel. Hydriding of Zr-1Nb alloy having a microstructure comprising equiaxed α grains and a uniform distribution of spherical particles of the β phase has been carried out in this study. The specimens have been hydrided by gaseous charging method to different hydrogen levels. The microstructures of hydrided samples were examined as a function of hydrogen content. The formation of δ hydride in slow cooled specimens and formation of γ hydride in rapidly cooled specimens has been studied with their morphology, habit plane and orientation relationship with the α matrix in view. The habit planes of either type of hydride phase has been determined and compared with those observed in other Zr-Nb alloys. The orientation relationship between the α matrix and the δ hydride was found to be the following: (0001) α // (111) δ and [1120] α // [110] δ . The orientation relationship between the α matrix and the γ hydride was of the following type: (0001) α // (111) γ and [1120] α // [110] γ . The internal structure of both types of hydride has been examined. The effect of the presence of the spherical β phase particles in the a matrix on the growth of the hydride plates has been investigated. (author)

  11. Sorption behaviour of herbicides in soils

    International Nuclear Information System (INIS)

    Luchini, L.C.; Wiendl, F.M.; Ruegg, E.F.; Instituto Biologico, Sao Paulo

    1988-01-01

    Environmental contamination by herbicides is related with the sorption phenomenon of these compounds in the soils. The behaviour of paraquat, 2,4-D and diuron was studied in soils with different physico-chemical properties, through the Freundlich adsorption and desorption isotherms, using 14 C-radiolabeled herbicides. Results of the range of the adsorption-desorption of each herbicide was related mainly with the chemical characteristics of these compounds. (author) [pt

  12. Phosphate sorption characteristics of European alpine soils

    Czech Academy of Sciences Publication Activity Database

    Kaňa, Jiří; Kopáček, Jiří; Camarero, L.; Garcia-Pausas, J.

    2011-01-01

    Roč. 75, č. 3 (2011), s. 862-870 ISSN 0361-5995 R&D Projects: GA ČR(CZ) GA526/09/0567; GA AV ČR(CZ) KJB600960907 Grant - others:EU EMERGE(CZ) EVK1-CT-1999-00032 Institutional research plan: CEZ:AV0Z60170517 Keywords : phosphate sorption * alpine soil s * acidification Subject RIV: DJ - Water Pollution ; Quality Impact factor: 1.979, year: 2011

  13. Moisture sorption isotherms of dehydrated whey proteins

    Directory of Open Access Journals (Sweden)

    Suzana Rimac Brnčić

    2010-03-01

    Full Text Available Moisture sorption isotherms describe the relation between the moisture content of the dry material (food and relative humidity of the surrounding environment. The data obtained are important in modelling of drying process conditions, packaging and shelf-life stability of food that will provide maximum retaining of aroma, colour and texture as well as nutritive and biological value. The objective of this research was to establish the equilibrium moisture content and water activity, as well as monolayer value of two commercial powdered whey protein isolates before and after tribomechanical micronisation and enzymatic hydrolysis, respectively. At the same time it was necessary to evaluate the best moisture sorption isotherm equation to fit the experimental data. The equilibrium moisture contents in investigated samples were determined using standard gravimetric method at 20 °C. The range of water activities was 0.11 to 0.75. The monolayer moisture content was estimated from sorption data using Brunauer-Emmett-Teller (BET and Guggenheim-Anderson-de Boer (GAB models. The results have shown that tribomechanically treated whey protein isolates as well as protein hydrolizates had lower monolayer moisture content values as well as higher corresponding water activity. Therefore, in spite of the fact that they have lower moisture content, they can be storage at higher relative humidity compared to untreated samples. BET model gave better fit to experimental sorption data for a water activity range from 0.11-0.54, while GAB model gave the closest fit for a water activity to 0.75.

  14. Moisture sorption isotherms of dehydrated whey proteins

    OpenAIRE

    Suzana Rimac Brnčić; Vesna Lelas; Zoran Herceg; Marija Badanjak

    2010-01-01

    Moisture sorption isotherms describe the relation between the moisture content of the dry material (food) and relative humidity of the surrounding environment. The data obtained are important in modelling of drying process conditions, packaging and shelf-life stability of food that will provide maximum retaining of aroma, colour and texture as well as nutritive and biological value. The objective of this research was to establish the equilibrium moisture content and water activity, as well as...

  15. Sorption studies of caesium by complex hexacyanoferrates

    International Nuclear Information System (INIS)

    Jacobi, D.

    1992-01-01

    A comprehensive literature review was carried out on the preparation of complex hexacyanoferrates in a granular form suitable for use in a packed column. The preparation of sodium nickel hexacyanoferrate using a freeze-thaw method was studied in detail and a method developed to produce a consistent and reproducible granular product. The equilibrium and sorption kinetics were studied using batch and column tests, and the process modelled to predict performance under various conditions. (author)

  16. Poisoning Experiments Aimed at Discriminating Active and Less-Active Sites of Silica-Supported Tantalum Hydride for Alkane Metathesis

    KAUST Repository

    Saggio, Guillaume; Taoufik, Mostafa; Basset, Jean-Marie; Thivolle-Cazat, Jean

    2010-01-01

    Only 50% of the silica-supported tantalum hydride sites are active in the metathesis of propane. Indeed, more than 45% of the tantalum hydride can be eliminated by a selective oxygen poisoning of inactive sites with no significant decrease

  17. Fluidized bed calciner

    International Nuclear Information System (INIS)

    Sheely, W.F.

    1986-01-01

    A unique way to convert radioactive scrap into useful nuclear fuel products was developed for the Department of Energy at Hanford. An advanced, fluidized bed calciner is used to convert metallic nitrate scrap or waste solutions into benign, solid and gaseous products. There are broad potential applications of this concept beyond those in the nuclear industry

  18. Nail Bed Injuries

    Science.gov (United States)

    ... All Topics A-Z Videos Infographics Symptom Picker Anatomy Bones Joints Muscles Nerves Vessels Tendons About Hand Surgery What is a Hand Surgeon? What is a Hand Therapist? Media Find a Hand Surgeon Home Anatomy Nail Bed Injuries Email to a friend * required ...

  19. Bed Bug Myths

    Science.gov (United States)

    Learn the truth about bed bugs, such as how easy they are to see with the naked eye, their preferred habitat, whether they transmit diseases, their public health effects, and whether pesticides are the best way to deal with an infestation.

  20. Assessment of Management Oxides for the Sorption of Radionuclides

    International Nuclear Information System (INIS)

    D.R. Learman; M.F. Hochella, Jr.

    2005-01-01

    Recent research has shown that certain manganese oxides have the ability to sorb aqueous metal cations much more efficiently than any of the naturally occurring iron oxides when normalized to surface area. This ability is, at least in part, related to the internal sites available in many manganese oxide structures, including those within tunnels and between sheets. Additionally, a new naturally-occurring manganese oxide structurally related to vernadite ((delta)-MnO 2 ), collected along the Clark Fork River in western Montana, USA, has shown the ability to sorb arsenate, an anionic complex. The potential for manganese oxides to sorb anions has made it an attractive material as a radionuclide ''getter''. According to the US Department of Energy's Total Systems Performance Assessment, technetium and iodine are two major anionic radionuclides contributing to the list of potential contaminants released from Yucca Mountain repository, Nevada, USA. These two radionuclides are extremely problematic because they are very mobile in the environment. This project involves running flow-through sorption experiments using rhenium (a surrogate for technetium) and stable iodine as sorbates and several synthetic manganese oxides, including birnessite, vernadite, cryptomelane, and possibly the new vernadite-like phase mentioned earlier, as sorbants. For all synthesis reactions, manganese (VII) salts are reduced to manganese (III,IV) oxides. The different oxides are produced from specific reductants and/or the addition of heat, followed by multiple washing steps. To verify that the proper phases have been synthesized, all oxides are analyzed using transmission electron microscopy (TEM) and powder X-ray diffraction (XRD). The sorption experiments will be run in flow-through reactors bearing the aqueous complex of interest, where solutions, at various temperatures, pH's, and ionic strengths, will pass through a bed of one of the manganese oxides. The effluent solution will be analyzed

  1. Sorption of antimony on human teeth

    International Nuclear Information System (INIS)

    Nofal, M.; Amin, H.; Alian, G.

    1997-01-01

    The study of the uptake of toxic elements on human teeth represents an interesting research area, as the fate of these elements when present in the human food is of health significance. Since antimony is one of the common toxic elements and since, the chemical behaviour of antimony is similar to that of arsenic, one of the most important toxic elements commonly encountered in cases of food poisoning, it has been decided to investigate its uptake on human teeth and on other restoration materials. The radioactive tracer technique was used to evaluate the concentration of antimony sorbed on teeth. This tracer was obtained by irradiation of antimony metal in the reactor, subsequent dissolution in concentrated sulphuric acid, evaporation to dryness and making the solution 6 M in Hydrochloric acid (1). Antimony prepared in this way is in the trivalent state (Sb III). Sorption was studied in water, tea, coffee, red tea and chicken soup. The highest sorption was achieved from water and chicken soup and least sorption was noticed in case of coffee. The results are presented in the form of the depletion of the radioactivity (A) of antimony with time in presence of a tooth in water and other drinks

  2. Radionuclide sorption studies on abyssal red clays

    International Nuclear Information System (INIS)

    Erickson, K.L.

    1979-01-01

    The radionuclide sorption properties of a widely distributed abyssal red clay are being experimentally investigated using batch equilibration techniques. This paper summarizes sorption equilibrium data obtained when 0.68 N NaCl solutions containing either Tc, U, Pu, Am or Cm were contacted with samples of the red clay and also summarizes some initial results from experiments designed to determine the relative selectivity of the clay for various nuclides. Under mildly oxidizing conditions, the sorption equilibrium distribution coefficients for technetium were essentially zero. At solution-phase nuclide concentrations on the order of 10 -6 M and less and at solution pH values of about 6.9, the distribution coefficients for plutonium were about 3 x 10 3 m1/gm and for uranium, americium, and curium were about 10 5 ml/gm or greater. However, at solution pH values of about 2.7, the distribution coefficients for each of the nuclides were greatly diminished. Initial experiments conducted in order to determine the relative selectivity of the clay for cesium, barium, and cerium, indicated that the silicate phases in the clay were selective for cesium over barium and cerium. These experiments also indicated that the hydrous oxide phases were selective for cerium over barium and for barium over cesium

  3. Lead sorption-desorption from organic residues.

    Science.gov (United States)

    Duarte Zaragoza, Victor M; Carrillo, Rogelio; Gutierrez Castorena, Carmen M

    2011-01-01

    Sorption and desorption are mechanisms involved in the reduction of metal mobility and bioavailability in organic materials. Metal release from substrates is controlled by desorption. The capacity of coffee husk and pulp residues, vermicompost and cow manure to adsorb Pb2+ was evaluated. The mechanisms involved in the sorption process were also studied. Organic materials retained high concentrations of lead (up to 36,000 mg L(-1)); however, the mechanisms of sorption varied according to the characteristics of each material: degree of decomposition, pH, cation exchange capacity and percentage of organic matter. Vermicompost and manure removed 98% of the Pb from solution. Lead precipitated in manure and vermicompost, forming lead oxide (PbO) and lead ferrite (PbFe4O7). Adsorption isotherms did not fit to the typical Freundlich and Langmuir equations. Not only specific and non-specific adsorption was observed, but also precipitation and coprecipitation. Lead desorption from vermicompost and cow manure was less than 2%. For remediation of Pb-polluted sites, the application of vermicompost and manure is recommended in places with alkaline soils because Pb precipitation can be induced, whereas coffee pulp residue is recommended for acidic soils where Pb is adsorbed.

  4. Bio sorption of uranium with Sargassum filipendula: use in treatment of effluents of laboratories

    International Nuclear Information System (INIS)

    Rodrigues Silva, J.I.; Melo Ferreira, A.C.; Costa, A.C.A. da

    2008-01-01

    International and National Standards establish methodologies for the management of radioactive waste in order to comply with radiological protection principles. Thus, it is necessary to find alternatives with both low cost and effective results. This work studied the use of brown algae Sargassum filipendula in its ability to remove uranium in waste generated in the environmental analysis laboratories of the Institute of Radiation Protection and Dosimetry. At first, the kinetics of bio sorption was studied. This experiment was conducted on a batch at concentrations of 1 mg/L and 100 mg/L. Mathematical models of the first and second order were used to fit the experimental results. In evaluating the maximum removal capacity by marine biomass on a batch, different uranium concentrations were analyzed, and iso terms of bio sorption were plotted. The experimental results have been adjusted by Langmuir and Freundlich models. The Freundlich model presented the best correlation coefficients (0.99 and 0.94) for studies with an hour and three hours of contact, respectively. In order to determine the best conditions for removal of uranium using the Sargassum filipendula, it was necessary to hold experiments in a continuous flow. A study on the critical height of bed depth was carried out by filling a column with different masses of seaweed. It was obtained a lower outlet concentration o f uranium (0.07 mg/L) in 40 cm bed depth. This best height of bed was applied to the waste treatment of SEANA laboratories. It was monitored the increase of retention in biomass for a known quantity of uranium. The results showed an excellent uptake of uranium (1.25 mg U/g of biomass) even in the presence of other metals and reagents. Decontamination of the effluent for uranium reached values below those set by CONAMA for water classes I and II, making it possible to reuse the water. (author)

  5. 7 CFR 2902.15 - Bedding, bed linens, and towels.

    Science.gov (United States)

    2010-01-01

    ... PROCUREMENT Designated Items § 2902.15 Bedding, bed linens, and towels. (a) Definition. (1) Bedding is that... minimum biobased content is 12 percent and shall be based on the amount of qualifying biobased carbon in..., and silk are not qualifying biobased feedstocks for the purpose of determining the biobased content of...

  6. Combined on-board hydride slurry storage and reactor system and process for hydrogen-powered vehicles and devices

    Science.gov (United States)

    Brooks, Kriston P; Holladay, Jamelyn D; Simmons, Kevin L; Herling, Darrell R

    2014-11-18

    An on-board hydride storage system and process are described. The system includes a slurry storage system that includes a slurry reactor and a variable concentration slurry. In one preferred configuration, the storage system stores a slurry containing a hydride storage material in a carrier fluid at a first concentration of hydride solids. The slurry reactor receives the slurry containing a second concentration of the hydride storage material and releases hydrogen as a fuel to hydrogen-power devices and vehicles.

  7. Mathematical Modeling of Moisture Sorption Isotherms and Determination of Isosteric Heats of Sorption of Ziziphus Leaves

    Directory of Open Access Journals (Sweden)

    Amel Saad

    2014-01-01

    Full Text Available Desorption and adsorption equilibrium moisture isotherms of Ziziphus spina-christi leaves were determined using the gravimetric-static method at 30, 40, and 50°C for water activity (aw ranging from 0.057 to 0.898. At a given aw, the results show that the moisture content decreases with increasing temperature. A hysteresis effect was observed. The experimental data of sorption were fitted by eight models (GAB, BET, Henderson-Thompson, modified-Chung Pfost, Halsey, Oswin, Peleg, and Adam and Shove. After evaluating the models according to several criteria, the Peleg and Oswin models were found to be the most suitable for describing the sorption curves. The net isosteric heats of desorption and adsorption of Ziziphus spina-christi leaves were calculated by applying the Clausius-Clapeyron equation to the sorption isotherms and an expression for predicting these thermodynamic properties was given.

  8. Geochemical modelling of the sorption of tetravalent radioelements

    International Nuclear Information System (INIS)

    Bond, K.A.; Tweed, C.J.

    1991-05-01

    The results of an experimental study of the sorption of a range of tetravalent radioelements, plutonium (IV), tin (IV), thorium(IV) and uranium(IV), onto clay at pH8 and pH11 have been successfully simulated using a triple layer sorption model. The model has been incorporated into HARPHRQ, a geochemical program based on PHREEQE. The model has been parameterised using data for sorption onto ferric oxyhydroxide and goethite. The effects of hydroxycarboxylic acids on the sorption process have also been investigated experimentally. It was generally observed that in the presence of 2x10 -3 M gluconate, sorption was reduced by up two orders of magnitude. The model has satisfactorily simulated these lower sorptivities, through assuming competing sorption and complexation reactions. This work, therefore, further confirms the need to take account of such organic materials in safety assessment modelling. (author)

  9. Investigation of metal ions sorption of brown peat moss powder

    Science.gov (United States)

    Kelus, Nadezhda; Blokhina, Elena; Novikov, Dmitry; Novikova, Yaroslavna; Chuchalin, Vladimir

    2017-11-01

    For regularities research of sorptive extraction of heavy metal ions by cellulose and its derivates from aquatic solution of electrolytes it is necessary to find possible mechanism of sorption process and to choice a model describing this process. The present article investigates the regularities of aliovalent metals sorption on brown peat moss powder. The results show that sorption isotherm of Al3+ ions is described by Freundlich isotherm and sorption isotherms of Na+ i Ni2+ are described by Langmuir isotherm. To identify the mechanisms of brown peat moss powder sorption the IR-spectra of the initial brown peat moss powder samples and brown peat moss powder samples after Ni (II) sorption were studied. Metal ion binding mechanisms by brown peat moss powder points to ion exchange, physical adsorption, and complex formation with hydroxyl and carboxyl groups.

  10. VA National Bed Control System

    Data.gov (United States)

    Department of Veterans Affairs — The VA National Bed Control System records the levels of operating, unavailable and authorized beds at each VAMC, and it tracks requests for changes in these levels....

  11. Getting Rid of Bed Bugs

    Science.gov (United States)

    ... Directory Planning, Budget and Results Jobs and Internships Headquarters Offices Regional Offices Labs and Research Centers Bed ... to be careful in how you select a company. Related Information Collaborative Strategy on Bed Bugs - highlights ...

  12. Hydrogen desorption kinetics from zirconium hydride and zirconium metal in vacuum

    International Nuclear Information System (INIS)

    Hu, Xunxiang; Terrani, Kurt A.; Wirth, Brian D.

    2014-01-01

    The kinetics of hydrogen desorption from zirconium hydride is important in many nuclear design and safety applications. In this paper, a coordinated experimental and modeling study has been used to explicitly demonstrate the applicability of existing kinetic theories for hydrogen desorption from zirconium hydride and α-zirconium. A static synthesis method was used to produce δ-zirconium hydride, and the crystallographic phases of the zirconium hydride were confirmed by X-ray diffraction (XRD). Three obvious stages, involving δ-zirconium hydride, a two-phase region, and α-zirconium, were observed in the hydrogen desorption spectra of two zirconium hydride specimens with H/Zr ratios of 1.62 and 1.64, respectively, which were obtained using thermal desorption spectroscopy (TDS). A continuous, one-dimensional, two-phase moving boundary model, coupled with the zero- and second-order kinetics of hydrogen desorption from δ-zirconium hydride and α-zirconium, respectively, has been developed to reproduce the TDS experimental results. A comparison of the modeling predictions with the experimental results indicates that a zero-order kinetic model is valid for description of hydrogen flux away from the δ-hydride phase, and that a second-order kinetic model works well for hydrogen desorption from α-Zr if the activation energy of desorption is optimized to be 70% of the value reported in the literature

  13. Pore-Confined Light Metal Hydrides for Energy Storage and Catalysis

    NARCIS (Netherlands)

    Bramwell, P.L.|info:eu-repo/dai/nl/371685117

    2017-01-01

    Light metal hydrides have enjoyed several decades of attention in the field of hydrogen storage, but their applications have recently begun to diversify more and more into the broader field of energy storage. For example, light metal hydrides have shown great promise as battery materials, in sensors

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

    International Nuclear Information System (INIS)

    Stout, R.B.

    2001-01-01

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

  15. Speculations on the existence of hydride ions in proton conducting oxides

    DEFF Research Database (Denmark)

    Poulsen, F.W.

    2001-01-01

    The chemical and physical nature of the hydride ion is briefly treated. Several reactions of the hydride ion in oxides or oxygen atmosphere are given, A number of perovskites and inverse perovskites are listed. which contain the H- ion on the oxygen or B-anion sites in the archetype ABO(3) System...

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

    Energy Technology Data Exchange (ETDEWEB)

    Stout, R.B. [California Univ., Livermore, CA (United States). Lawrence Livermore National Lab

    2001-07-01

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

  17. 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

  18. Hydrogen storage material and process using graphite additive with metal-doped complex hydrides

    Science.gov (United States)

    Zidan, Ragaiy [Aiken, SC; Ritter, James A [Lexington, SC; Ebner, Armin D [Lexington, SC; Wang, Jun [Columbia, SC; Holland, Charles E [Cayce, SC

    2008-06-10

    A hydrogen storage material having improved hydrogen absorbtion and desorption kinetics is provided by adding graphite to a complex hydride such as a metal-doped alanate, i.e., NaAlH.sub.4. The incorporation of graphite into the complex hydride significantly enhances the rate of hydrogen absorbtion and desorption and lowers the desorption temperature needed to release stored hydrogen.

  19. Hydride-induced degradation of hoop ductility in textured zirconium-alloy tubes: A theoretical analysis

    International Nuclear Information System (INIS)

    Qin, W.; Szpunar, J.A.; Kozinski, J.

    2012-01-01

    Hydride-induced degradation of hoop ductility in Zr-alloy tubular components has been studied for many years because of its importance in the nuclear industry. In this paper the role of intergranular and intragranular δ-hydrides in the degradation of ductility of the textured Zr-alloy tubes is investigated. The correlation among hydride distribution, orientation and morphology in the tubes is formulated based on thermodynamic modeling, and then analyzed. The results show that the applied stress, the crystallographic texture of α-Zr matrix, the grain-boundary structure, and the morphology and size of Zr grains simultaneously govern the site preference and the orientation of hydrides. A criterion is proposed to determine the threshold stress of hydride reorientation. The hoop ductility of the hydrided Zr tubes is discussed using the concept of macroscopic fracture strain. It is shown that the intergranular hydrides may be more deleterious to ductility than the intragranular ones. This work defines a general framework for understanding the relation of the microstructure of hydride-forming materials to embrittlement.

  20. Mechanisms of chemical generation of volatile hydrides for trace element determination (IUPAC Technical Report)

    Czech Academy of Sciences Publication Activity Database

    D'Ulivo, A.; Dědina, Jiří; Mester, Z.; Sturgeon, R. E.; Wang, Q.; Welz, B.

    2011-01-01

    Roč. 83, č. 6 (2011), s. 1283-1340 ISSN 0033-4545 Institutional research plan: CEZ:AV0Z40310501 Keywords : borane complexes * chemical generation of volatile hydrides (CHG) * volatile hydrides Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 2.789, year: 2011

  1. Sorption of citalopram, irbesartan and fexofenadine in soils: Estimation of sorption coefficients from soil properties.

    Science.gov (United States)

    Klement, Aleš; Kodešová, Radka; Bauerová, Martina; Golovko, Oksana; Kočárek, Martin; Fér, Miroslav; Koba, Olga; Nikodem, Antonín; Grabic, Roman

    2018-03-01

    The sorption of 3 pharmaceuticals, which may exist in 4 different forms depending on the solution pH (irbesartan in cationic, neutral and anionic, fexofenadine in cationic, zwitter-ionic and anionic, and citalopram cationic and neutral), in seven different soils was studied. The measured sorption isotherms were described by Freundlich equations, and the sorption coefficients, K F (for the fixed n exponent for each compound), were related to the soil properties to derive relationships for estimating the sorption coefficients from the soil properties (i.e., pedotransfer rules). The largest sorption was obtained for citalopram (average K F value for n = 1 was 1838 cm 3  g -1 ) followed by fexofenadine (K F  = 35.1 cm 3/n μg 1-1/n g -1 , n = 1.19) and irbesartan (K F  = 3.96 cm 3/n μg 1-1/n g -1 , n = 1.10). The behavior of citalopram (CIT) in soils was different than the behaviors of irbesartan (IRB) and fexofenadine (FEX). Different trends were documented according to the correlation coefficients between the K F values for different compounds (R IRB,FEX  = 0.895, p-valuesoil properties in the pedotransfer functions. While the K F value for citalopram was positively related to base cation saturation (BCS) or sorption complex saturation (SCS) and negatively correlated to the organic carbon content (Cox), the K F values of irbesartan and fexofenadine were negatively related to BCS, SCS or the clay content and positively related to Cox. The best estimates were obtained by combining BCS and Cox for citalopram (R 2  = 93.4), SCS and Cox for irbesartan (R 2  = 96.3), and clay content and Cox for fexofenadine (R 2  = 82.9). Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Deep Bed Iodine Sorbent Testing FY 2011 Report

    International Nuclear Information System (INIS)

    Soelberg, Nick; Watson, Tony

    2011-01-01

    Nuclear fission results in the production of fission products (FPs) and activation products that increasingly interfere with the fission process as their concentrations increase. Some of these fission and activation products tend to evolve in gaseous species during used nuclear fuel reprocessing. Analyses have shown that I129, due to its radioactivity, high potential mobility in the environment, and high longevity (half life of 15.7 million years), can require control efficiencies of up to 1,000x or higher to meet regulatory emission limits. Deep-bed iodine sorption testing has been done to evaluate the performance of solid sorbents for capturing iodine in off-gas streams from nuclear fuel reprocessing plants. The objectives of the FY 2011 deep bed iodine sorbent testing are: (1) Evaluate sorbents for iodine capture under various conditions of gas compositions and operating temperature (determine sorption efficiencies, capacities, and mass transfer zone depths); and (2) Generate data for dynamic iodine sorption modeling. Three tests performed this fiscal year on silver zeolite light phase (AgZ-LP) sorbent are reported here. Additional tests are still in progress and can be reported in a revision of this report or a future report. Testing was somewhat delayed and limited this year due to initial activities to address some questions of prior testing, and due to a period of maintenance for the on-line GC. Each test consisted of (a) flowing a synthetic blend of gases designed to be similar to an aqueous dissolver off-gas stream over the sorbent contained in three separate bed segments in series, (b) measuring each bed inlet and outlet gas concentrations of iodine and methyl iodide (the two surrogates of iodine gas species considered most representative of iodine species expected in dissolver off-gas), (c) operating for a long enough time to achieve breakthrough of the iodine species from at least one (preferably the first two) bed segments, and (d) post-test purging

  3. Trapping interference effects of arsenic, antimony and bismuth hydrides in collection of selenium hydride within iridium-modified transversally-heated graphite tube atomizer

    Energy Technology Data Exchange (ETDEWEB)

    Furdikova, Zuzana [Department of Environmental Chemistry and Technology, Faculty of Chemistry, Brno University of Technology, Purkynova 118, CZ-61200 Brno (Czech Republic); Institute of Analytical Chemistry of the Academy of Sciences of the Czech Republic v.v.i., Veveri 97, CZ-60200, Brno (Czech Republic); Docekal, Bohumil [Institute of Analytical Chemistry of the Academy of Sciences of the Czech Republic v.v.i., Veveri 97, CZ-60200, Brno (Czech Republic)], E-mail: docekal@iach.cz

    2009-04-15

    Interference effects of co-generated hydrides of arsenic, antimony and bismuth on trapping behavior of selenium hydride (analyte) within an iridium-modified, transversely heated graphite tube atomizer (THGA) were investigated. A twin-channel hydride generation system was used for independent separate generation and introduction of analyte and interferent hydrides, i.e. in a simultaneous and/or sequential analyte-interferent and interferent-analyte mode of operation. The influence of the analyte and modifier mass, interferent amount, trapping temperature and composition of the gaseous phase was studied. A simple approach for the elimination of mutual interference effects by modification of the gaseous phase with oxygen in a substoichiometric ratio to chemically generated hydrogen is proposed and the suppression of these interference effects is demonstrated. A hypothesis on the mechanism of trapping and mutual interference effects is drawn.

  4. Influence of selected factors on strontium sorption on bentonites

    International Nuclear Information System (INIS)

    Galambos, M.; Kufcakova, J.; Rajec, P.

    2007-01-01

    Sorption on bentonite will play an important role in retarding the migration of radionuclides from a waste repository. Bentonite is a natural clay and one of the most promising candidates for use as a buffer material in the geological disposal systems for high-level nuclear waste. It is intended to isolate metal canisters with highly radioactive waste products from the surrounding rocks because of its ability to retard the movement of radionuclides by sorption. Bentonite is characterized by low permeability, water swelling capability and excellent sorption potential for cationic radionuclides. To correctly assess the sorption potential of radionuclides on bentonite is essential for the development of predictive migration models. The sorption of strontium on bentonite from different Slovak deposits - Jelsovy potok, Kopernica and Lieskovec has been investigated under various experimental conditions, such as contact time, sorbate concentrations, presence of complementary cation. Sorption was studied using the batch technique. The uptake of Sr was rapid and equilibrium was reached almost instantaneously. The instantaneous uptake may be due to adsorption and/or exchange of the metal with some ions on the surface of the adsorbent. The best sorption characteristics distinguish bentonite Kopernica, sorption capacity for Sr of the fraction under 45 mm is 0,48 mmol·g -1 for Sr. The highest values of distribution coefficient were reached for the bentonite Jelsovy potok. Radiation stability has been investigated, the higher sorption parameters were observed for the irradiated bentonites, which can be explained by the increase of specific surface of the bentonite samples. The presence of complementary cations depresses the sorption of Sr on bentonite. Cations Ca 2+ exhibit higher effect on cesium sorption than the Na 2+ ions. Results indicate that the sorption of Sr 2+ on bentonite will be affected by the presence of high concentrations of various salts in the waste water

  5. suitability of murram for phosphorus sorption in constructed wetlands

    African Journals Online (AJOL)

    Mimi

    sorption isotherms, determination of Phosphorus sorption capacity of the substrates, determination of. Phosphorus sorption as the function of time and determination of effect of temperature on the ... (Na2O + K2O) % SiO2. %. P2O5. %. TiO2. %. LOI. %. 19.2. 1.3. 0.69. 5.13. 0.05. 6.7. 61.9. 0.04. 0.51. 4.4. As presented in ...

  6. Mechanism of cesium sorption on potassium titanium hexacyanoferrate

    International Nuclear Information System (INIS)

    Sun Yongxia; Xu Shiping; Song Chongli

    1998-01-01

    The mechanism of cesium sorption on potassium titanium hexacyanoferrate is described. The dependence of the sorption speed on temperature, particle granule size, and the stirring speed is studied. The results show that the sorption process is controlled by liquid film diffusion and particle diffusion. An exchange reaction occurs mainly between K + in the exchanger and Cs + in the solution, i.e. potassium titanium hexacyanoferrate, and Cs + of simulated high-level liquid waste

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1995-09-01

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

  8. Single-Site Tetracoordinated Aluminum Hydride Supported on Mesoporous Silica. From Dream to Reality!

    KAUST Repository

    Werghi, Baraa

    2016-09-26

    The reaction of mesoporous silica (SBA15) dehydroxylated at 700 °C with diisobutylaluminum hydride, i-Bu2AlH, gives after thermal treatment a single-site tetrahedral aluminum hydride with high selectivity. The starting aluminum isobutyl and the final aluminum hydride have been fully characterized by FT-IR, advanced SS NMR spectroscopy (1H, 13C, multiple quanta (MQ) 2D 1H-1H, and 27Al), and elemental analysis, while DFT calculations provide a rationalization of the occurring reactivity. Trimeric i-Bu2AlH reacts selectively with surface silanols without affecting the siloxane bridges. Its analogous hydride catalyzes ethylene polymerization. Indeed, catalytic tests show that this single aluminum hydride site is active in the production of a high-density polyethylene (HDPE). © 2016 American Chemical Society.

  9. Getting metal-hydrides to do what you want them to

    International Nuclear Information System (INIS)

    Gruen, D.M.

    1981-01-01

    With the discovery of AB 5 compounds, intermetallic hydrides with unusual properties began to be developed (H dissociation pressures of one to several atmospheres, extremely rapid and reversible adsorption/desorption very large amounts of H adsorbed). This paper reviews the factors that must be controlled in order to modify these hydrides to make them useful. The system LaNi 5 + H 2 is used as example. Use of AB 5 hydrides to construct a chemical heat pumps is discussed. Results of a systematic study substituting Al for Ni are reported; the HYCSOS pump is described briefly. Use of hydrides as hydrogen getters (substituted ZrV 2 ) is also discussed. Finally, possible developments in intermetallic hydride research in the 1980's and the hydrogen economy are discussed. 10 figures

  10. Single-Site Tetracoordinated Aluminum Hydride Supported on Mesoporous Silica. From Dream to Reality!

    KAUST Repository

    Werghi, Baraa; Bendjeriou-Sedjerari, Anissa; Jedidi, Abdesslem; Abou-Hamad, Edy; Cavallo, Luigi; Basset, Jean-Marie

    2016-01-01

    The reaction of mesoporous silica (SBA15) dehydroxylated at 700 °C with diisobutylaluminum hydride, i-Bu2AlH, gives after thermal treatment a single-site tetrahedral aluminum hydride with high selectivity. The starting aluminum isobutyl and the final aluminum hydride have been fully characterized by FT-IR, advanced SS NMR spectroscopy (1H, 13C, multiple quanta (MQ) 2D 1H-1H, and 27Al), and elemental analysis, while DFT calculations provide a rationalization of the occurring reactivity. Trimeric i-Bu2AlH reacts selectively with surface silanols without affecting the siloxane bridges. Its analogous hydride catalyzes ethylene polymerization. Indeed, catalytic tests show that this single aluminum hydride site is active in the production of a high-density polyethylene (HDPE). © 2016 American Chemical Society.

  11. The status and immediate problems of the chemistry of transition metal hydrides

    International Nuclear Information System (INIS)

    Meikheeva, V.I.

    1978-01-01

    The state of the art and perspectives of the chemistry transition metal hydrides are reviewed, the hydrides being essentially compounds with interstitial hydrogen in the crystal lattice of the metals. The possibilities of hydrogenation of transition metals are considered along with that of compounds of rare earth elements with metals of the iron family. It is shown that the products of hydrogenation of many alloys are unstable and disintegrate forming simpler hydrides. The phase diagram of La-Ni-H system resembles the isotherm of a ternary metal system with the difference that no continuous series of solid solutions is formed. Most hydrogenation products across LaHsub(2-3)-NiH are X-ray amorphous. The nature of hydrogen in hydrides is discussed along with the possibilities of synthesis of new hydrides of transition metals

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

    International Nuclear Information System (INIS)

    Cheong, Y. M.; Kim, Y. S.; Gong, U. S.; Kwon, S. C.; Kim, S. S.; Choo, K.N.

    2000-09-01

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

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

    Science.gov (United States)

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

    2015-04-02

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

  14. Roles of texture in controlling oxidation, hydrogen ingress and hydride formation in Zr alloys

    International Nuclear Information System (INIS)

    Szpunar, Jerzy A.; Qin, Wen; Li, Hualong; Kumar, Kiran

    2011-01-01

    Experimental observations shows that the oxide formed on Zr alloys are strongly textured. The texture and grain-boundary characteristics of oxide are dependent on the texture of metal substrate. Computer simulation and thermodynamic modeling clarify the effect of metal substrate on structure of oxide film, and intrinsic factors affecting the microstructure. Models of diffusion process of hydrogen atoms and oxygen diffusion through oxide are presented. Both intra-granular and inter-granular hydrides were found following (0001) α-Zr //(111) δ-ZrH1.5 relationship. The through-thickness texture inhomogeneity in cladding tubes, the effects of hoop stress on the hydride orientation and the formation of interlinked hydride structure were studied. A thermodynamic model was developed to analyze the nucleation and the stress-induced reorientation of intergranular hydrides. These works provide a framework for understanding the oxidation, the hydrogen ingress and the hydride formation in Zr alloys. (author)

  15. Analytical and numerical models of uranium ignition assisted by hydride formation

    International Nuclear Information System (INIS)

    Totemeier, T.C.; Hayes, S.L.

    1996-01-01

    Analytical and numerical models of uranium ignition assisted by the oxidation of uranium hydride are described. The models were developed to demonstrate that ignition of large uranium ingots could not occur as a result of possible hydride formation during storage. The thermodynamics-based analytical model predicted an overall 17 C temperature rise of the ingot due to hydride oxidation upon opening of the storage can in air. The numerical model predicted locally higher temperature increases at the surface; the transient temperature increase quickly dissipated. The numerical model was further used to determine conditions for which hydride oxidation does lead to ignition of uranium metal. Room temperature ignition only occurs for high hydride fractions in the nominally oxide reaction product and high specific surface areas of the uranium metal

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

    Energy Technology Data Exchange (ETDEWEB)

    Cheong, Y M; Kim, Y S; Gong, U S; Kwon, S C; Kim, S S; Choo, K N

    2000-09-01

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

  17. Prevention of delayed hydride cracking in zirconium alloys

    International Nuclear Information System (INIS)

    Cheadle, B.A.; Coleman, C.E.; Ambler, J.F.R.

    1987-01-01

    Zirconium alloys are susceptible to a mechanism for crack initiation and propagation called delayed hydride cracking. From a review of component failures and experimental results, we have developed the requirements for preventing this cracking. The important parameters for cracking are hydrogen concentration, flaws, and stress; each should be minimized. At the design and construction stages hydrogen pickup has to be controlled, quality assurance needs to be at a high enough level to ensure the absence of flaws, and residual stresses must be eliminated by careful fabrication and heat treatment

  18. Hydrogen isotope exchange in a metal hydride tube

    Energy Technology Data Exchange (ETDEWEB)

    Robinson, David B. [Sandia National Lab. (SNL-CA), Livermore, CA (United States)

    2014-09-01

    This report describes a model of the displacement of one hydrogen isotope within a metal hydride tube by a different isotope in the gas phase that is blown through the tube. The model incorporates only the most basic parameters to make a clear connection to the theory of open-tube gas chromatography, and to provide a simple description of how the behavior of the system scales with controllable parameters such as gas velocity and tube radius. A single tube can be seen as a building block for more complex architectures that provide higher molar flow rates or other advanced design goals.

  19. Modification of the hydriding of uranium using ion implantation

    International Nuclear Information System (INIS)

    Musket, R.G.; Robinson-Weis, G.; Patterson, R.G.

    1983-01-01

    The hydriding of depleted uranium at 76 Torr hydrogen and 130 0 C has been significantly reduced by implantation of oxygen ions. The high-dose implanted specimens had incubation times for the initiation of the reaction after exposure to hydrogen that exceeded those of the nonimplanted specimens by more than a factor of eight. Furthermore, the nonimplanted specimens consumed enough hydrogen to cause macroscopic flaking of essentially the entire surface in times much less than the incubation time for the high-dose implanted specimens. In contrast, the ion-implanted specimens reacted only at isolated spots with the major fraction of the surface area unaffected by the hydrogen exposure

  20. Research in Nickel/Metal Hydride Batteries 2016

    Directory of Open Access Journals (Sweden)

    Kwo-Hsiung Young

    2016-10-01

    Full Text Available Nineteen papers focusing on recent research investigations in the field of nickel/metal hydride (Ni/MH batteries have been selected for this Special Issue of Batteries. These papers summarize the joint efforts in Ni/MH battery research from BASF, Wayne State University, the National Institute of Standards and Technology, Michigan State University, and FDK during 2015–2016 through reviews of basic operational concepts, previous academic publications, issued US Patent and filed Japan Patent Applications, descriptions of current research results in advanced components and cell constructions, and projections of future works.

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

    International Nuclear Information System (INIS)

    Zou Lexi; Sun Ying; Xue Weidong; Zhu Zhenghe; Wang Rong; Luo Deli

    2002-01-01

    There are six independent constituents with 4 chemical elements, i.e. PuH 2.7 (s), PuN(s), Pu 2 O 3 (s), N 2 , O 2 and H 2 , therefore, the system described involves of 2 independent reactions, both ΔG 0 <<0. The calculated equilibrium compositions are in agreement with those of the experimental, which indicates that the chemical equilibrium is nearly completely approached. Therefore, it is believed that the reaction rate of plutonium hydride with air is extremely rapid. The author has briefly discussed the simultaneous reactions and its thermodynamic coupling effect

  2. Sorption of curium by silica colloids: Effect of humic acid

    International Nuclear Information System (INIS)

    Kar, Aishwarya Soumitra; Kumar, Sumit; Tomar, B.S.; Manchanda, V.K.

    2011-01-01

    Sorption of curium by silica colloids has been studied as a function of pH and ionic strength using 244 Cm as a tracer. The sorption was found to increase with increasing pH and reach a saturation value of ∼95% at pH beyond 5.3. The effect of humic acid on the sorption of 244 Cm onto silica was studied by changing the order of addition of the metal ion and humic acid. In general, in the presence of humic acid (2 mg/L), the sorption increased at lower pH (<5) while it decreased in the pH range 6.5-8 and above pH 8, the sorption was found to increase again. As curium forms strong complex with humic acid, its presence results in the enhancement of curium sorption at lower pH. At higher pH the humic acid present in the solution competes with the surface sites for curium thus decreasing the sorption. The decrease in the Cm sorption in presence of humic acid was found to be less when humic acid was added after the addition of curium. Linear additive model qualitatively reproduced the profile of the Cm(III) sorption by silica in presence of humic acid at least in the lower pH region, however it failed to yield quantitative agreement with the experimental results. The results of the present study evidenced the incorporation of Cm into the silica matrix.

  3. Development of Web-based Software for Sorption Database

    International Nuclear Information System (INIS)

    Han, Byoung Sub; Lee, Jae Min; Seo, Min Seok; Kim, Dong Keon

    2009-08-01

    Sorption studies of radionuclides are important parts of research on radioactive waste disposal which is commonly faced in most countries where nuclear programs (power production, a variety of peaceful applications, and research) are implemented. The Sorption Database (DB) plays a very important role in the safety assessment of the radioactive waste disposal. The Sorption DB which is opened externally can be used as reference material of establishing a national policy by improving and changing the pre-developed Sorption program to be web-based. From the industrial point of view, if the Sorption DB is opened to the outside, the safety-related confidence can be achieved for nuclear industry. As the information of Sorption DB is opened, not only credibility can be provided to the administration, local governments and nearby residents, but also input of the collected information can be achieved by online. In addition, the reference material and external awareness/reliability about the domestic level of the Sorption DB management system and the current state can be achieved internationally. In order to provide the information of Sorption DB to users in more efficient way, the analysis and complement of management and search capability for the existing Sorption DB program have been performed and web-based management system has been built to provide services to users. In addition, by applying statistical techniques, it has been designed and implemented to display the accuracy and error of the information

  4. Determining Sorption Rate by a Continuous Gravimetric Method

    National Research Council Canada - National Science Library

    Hall, Monicia R; Procell, Lawrence R; Bartram, Philip W; Shuely, Wendel J

    2003-01-01

    ... were automatically recorded in an Excel file while CARC coupons were submerged in solvent. Initial sorption rates were determined for butyl acetate, butyl ether, cyclohexane and propylene carbonate...

  5. The sorption of polonium, actinium and protactinium onto geological materials

    International Nuclear Information System (INIS)

    Baston, G.M.N.; Berry, J.A.; Brownsword, M.; Heath, T.G.; Ilett, D.J.; McCrohon, R.; Tweed, C.J.; Yui, M.

    1999-01-01

    This paper describes a combined experimental and modeling program of generic sorption studies to increase confidence in the performance assessment for a potential high-level radioactive waste repository in Japan. The sorption of polonium, actinium and protactinium onto geological materials has been investigated. Sorption of these radioelements onto bentonite, tuff and granodiorite from equilibrated de-ionized water was studied under reducing conditions at room temperature. In addition, the sorption of actinium and protactinium was investigated at 60 C. Thermodynamic chemical modeling was carried out to aid interpretation of the results

  6. The sorption of polonium, actinium and protactinium onto geological materials

    Energy Technology Data Exchange (ETDEWEB)

    Baston, G.M.N.; Berry, J.A.; Brownsword, M.; Heath, T.G.; Ilett, D.J.; McCrohon, R.; Tweed, C.J.; Yui, M.

    1999-07-01

    This paper describes a combined experimental and modeling program of generic sorption studies to increase confidence in the performance assessment for a potential high-level radioactive waste repository in Japan. The sorption of polonium, actinium and protactinium onto geological materials has been investigated. Sorption of these radioelements onto bentonite, tuff and granodiorite from equilibrated de-ionized water was studied under reducing conditions at room temperature. In addition, the sorption of actinium and protactinium was investigated at 60 C. Thermodynamic chemical modeling was carried out to aid interpretation of the results.

  7. Comparison of neptunium sorption results using batch and column techniques

    International Nuclear Information System (INIS)

    Triay, I.R.; Furlano, A.C.; Weaver, S.C.; Chipera, S.J.; Bish, D.L.

    1996-08-01

    We used crushed-rock columns to study the sorption retardation of neptunium by zeolitic, devitrified, and vitric tuffs typical of those at the site of the potential high-level nuclear waste repository at Yucca Mountain, Nevada. We used two sodium bicarbonate waters (groundwater from Well J-13 at the site and water prepared to simulate groundwater from Well UE-25p No. 1) under oxidizing conditions. It was found that values of the sorption distribution coefficient, Kd, obtained from these column experiments under flowing conditions, regardless of the water or the water velocity used, agreed well with those obtained earlier from batch sorption experiments under static conditions. The batch sorption distribution coefficient can be used to predict the arrival time for neptunium eluted through the columns. On the other hand, the elution curves showed dispersivity, which implies that neptunium sorption in these tuffs may be nonlinear, irreversible, or noninstantaneous. As a result, use of a batch sorption distribution coefficient to calculate neptunium transport through Yucca Mountain tuffs would yield conservative values for neptunium release from the site. We also noted that neptunium (present as the anionic neptunyl carbonate complex) never eluted prior to tritiated water, which implies that charge exclusion does not appear to exclude neptunium from the tuff pores. The column experiments corroborated the trends observed in batch sorption experiments: neptunium sorption onto devitrified and vitric tuffs is minimal and sorption onto zeolitic tuffs decreases as the amount of sodium and bicarbonate/carbonate in the water increases

  8. Experimental study of strontium sorption on fissure filling material

    Energy Technology Data Exchange (ETDEWEB)

    Eriksen, T E; Cui, Daqing [Royal Institute of Technology, Stockholm (Sweden). Dept. of Chemistry

    1994-12-01

    We have carried out a comparative study of sorption and desorption of strontium in groundwater on separated magnetic and size fractions of fissure filling material taken from natural fissures in granitic rock. Complete reversibility of the sorption process was demonstrated by identical Freundlich isotherms, isotopic exchangeability and pH dependence of the distribution coefficients Rd. The sorption was found to be strongly pH dependent in the range 3-11. The pH effect can be accommodated in the sorption model by considering the surface areas and surface charges of the minerals in the fissure filling material. 20 refs, 9 figs, 3 tabs.

  9. Experimental study of strontium sorption on fissure filling material

    International Nuclear Information System (INIS)

    Eriksen, T.E.; Cui, Daqing

    1994-12-01

    We have carried out a comparative study of sorption and desorption of strontium in groundwater on separated magnetic and size fractions of fissure filling material taken from natural fissures in granitic rock. Complete reversibility of the sorption process was demonstrated by identical Freundlich isotherms, isotopic exchangeability and pH dependence of the distribution coefficients Rd. The sorption was found to be strongly pH dependent in the range 3-11. The pH effect can be accommodated in the sorption model by considering the surface areas and surface charges of the minerals in the fissure filling material. 20 refs, 9 figs, 3 tabs

  10. Acquisition of sorption isotherms for modified woods by the use of dynamic vapour sorption instrumentation. Principles and Practice

    DEFF Research Database (Denmark)

    Engelund, Emil Tang; Klamer, Morten; Venås, Thomas Mark

    2010-01-01

    The complex wood-water relationship has been the topic of numerous studies. Sorption isotherms – in particular – have been derived for hundreds of wood species, their sap- and heartwood sections as well as for decayed, engineered and modified wood materials. However, the traditional methods...... for obtaining sorption isotherms are very time consuming. With new dynamic vapour sorption (DVS) instrumentation, the acquisition of data for constructing sorption isotherms is suddenly dramatically lowered. Where the traditional methods often required months, data can now be obtained in a matter of days...... depending on the number of data points required. The fast data acquisition makes DVS a useful tool in studying the sorption properties of wood, and especially in studying the effect of different modification treatments on these properties. This study includes an investigation of the sorption properties...

  11. Geomechanics of bedded salt

    International Nuclear Information System (INIS)

    Serata, S.; Milnor, S.W.

    1979-01-01

    Creep data from the literature search is reinterpreted by SGI, resulting in a better understanding of the temperature and stress state dependence of the octahedral creep rate and the octahedral shear strength. The concept of a transition strength between the elastic and the plastic states is in agreement with the data. The elastic and rheological properties of salt are described, and a set of constitutive equations is presented. The dependence of material properties on parameters such as temperature is considered. Findings on the permeability of salt are summarized, and the in-situ behavior of openings in bedded salt is described based on extensive engineering experience. A stress measuring system utilizing a finite element computer code is discussed. Geological factors affecting the stability of salt openings are considered, and the Stress Control Technique for designing stable openings in bedded salt formations is explained

  12. Lignite air-steam gasification in the fluidized bed of iron-containing slag catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Kuznetsov, B.N.; Shchipko, M.L.; Golovin, Yu. [Inst. of Chemistry of Natural Organic Materials, Academgorodok, Krasnoyarsk (Russian Federation)

    1995-12-01

    The influence of fluidized bed of iron-containing slag particles on air-steam gasification of powdered Kansk-Achinsk lignite in entrained flow was studied in pilot installation with productivity about 60 kg per hour. Slag of Martin process and boiler slag were used as catalytic active materials until their complete mechanical attrition. Two following methods of catalytic gasification of lignite were compared: the partial gasification in stationary fluidized bed of slag particles with degree of fuel conversion 40-70% and complete gasification in circulating bed of slag particles. In the first case only the most reactive part of fuel is gasified with the simultaneously formation of porous carbon residue with good sorption ability. It was found the catalytic fluidized bed improves heat transfer from combustion to reduction zone of gas-generator and increases the rate of fuel conversion at the temperature range 900-1000{degrees}C. At these temperatures the degree of conversion is depended considerably on the duration time of fuel particles in the catalytic fluidized bed. The influence of catalytic fluidized bed height and velocity of reaction mixture on the temperature profiles in the gas-generator was studied. The optimal relationship was found between the fluidized bed height and velocity of flow which makes possible to produce the gas with higher calorific value at maximum degree of fuel conversion.

  13. 3.3. Sorption activity of cross-linked polymers of ethynyl-piperidol

    International Nuclear Information System (INIS)

    Khalikov, D.Kh.

    2012-01-01

    The sorption activity of cross-linked polymers of ethynyl-piperidol was studied. The bilirubin sorption was studied as well. The kinetic of bilirubin sorption and human serum albumin at their joint presence in hydrogel solutions was defined. Bilirubin sorption and change of albumin composition was considered. The sorption of middle molecular peptides was considered as well. The sorption of endogenous toxin by means of ethynyl-piperidol polymers was done.

  14. Sorption Modeling and Verification for Off-Gas Treatment

    Energy Technology Data Exchange (ETDEWEB)

    Tavlarides, Lawrence L. [Syracuse Univ., NY (United States); Lin, Ronghong [Syracuse Univ., NY (United States); Nan, Yue [Syracuse Univ., NY (United States); Yiacoumi, Sotira [Georgia Inst. of Technology, Atlanta, GA (United States); Tsouris, Costas [Georgia Inst. of Technology, Atlanta, GA (United States); Ladshaw, Austin [Georgia Inst. of Technology, Atlanta, GA (United States); Sharma, Ketki [Georgia Inst. of Technology, Atlanta, GA (United States); Gabitto, Jorge [Prairie View A & M Univ., Prairie View, TX (United States); DePaoli, David [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-04-29

    The project has made progress toward developing a comprehensive modeling capability for the capture of target species in off gas evolved during the reprocessing of nuclear fuel. The effort has integrated experimentation, model development, and computer code development for adsorption and absorption processes. For adsorption, a modeling library has been initiated to include (a) equilibrium models for uptake of off-gas components by adsorbents, (b) mass transfer models to describe mass transfer to a particle, diffusion through the pores of the particle and adsorption on the active sites of the particle, and (c) interconnection of these models to fixed bed adsorption modeling which includes advection through the bed. For single-component equilibria, a Generalized Statistical Thermodynamic Adsorption (GSTA) code was developed to represent experimental data from a broad range of isotherm types; this is equivalent to a Langmuir isotherm in the two-parameter case, and was demonstrated for Kr on INL-engineered sorbent HZ PAN, water sorption on molecular sieve A sorbent material (MS3A), and Kr and Xe capture on metal-organic framework (MOF) materials. The GSTA isotherm was extended to multicomponent systems through application of a modified spreading pressure surface activity model and generalized predictive adsorbed solution theory; the result is the capability to estimate multicomponent adsorption equilibria from single-component isotherms. This advance, which enhances the capability to simulate systems related to off-gas treatment, has been demonstrated for a range of real-gas systems in the literature and is ready for testing with data currently being collected for multicomponent systems of interest, including iodine and water on MS3A. A diffusion kinetic model for sorbent pellets involving pore and surface diffusion as well as external mass transfer has been established, and a methodology was developed for determining unknown diffusivity parameters from transient

  15. Sorption Modeling and Verification for Off-Gas Treatment

    International Nuclear Information System (INIS)

    Tavlarides, Lawrence L.; Lin, Ronghong; Nan, Yue; Yiacoumi, Sotira; Tsouris, Costas; Ladshaw, Austin; Sharma, Ketki; Gabitto, Jorge; DePaoli, David

    2015-01-01

    The project has made progress toward developing a comprehensive modeling capability for the capture of target species in off gas evolved during the reprocessing of nuclear fuel. The effort has integrated experimentation, model development, and computer code development for adsorption and absorption processes. For adsorption, a modeling library has been initiated to include (a) equilibrium models for uptake of off-gas components by adsorbents, (b) mass transfer models to describe mass transfer to a particle, diffusion through the pores of the particle and adsorption on the active sites of the particle, and (c) interconnection of these models to fixed bed adsorption modeling which includes advection through the bed. For single-component equilibria, a Generalized Statistical Thermodynamic Adsorption (GSTA) code was developed to represent experimental data from a broad range of isotherm types; this is equivalent to a Langmuir isotherm in the two-parameter case, and was demonstrated for Kr on INL-engineered sorbent HZ PAN, water sorption on molecular sieve A sorbent material (MS3A), and Kr and Xe capture on metal-organic framework (MOF) materials. The GSTA isotherm was extended to multicomponent systems through application of a modified spreading pressure surface activity model and generalized predictive adsorbed solution theory; the result is the capability to estimate multicomponent adsorption equilibria from single-component isotherms. This advance, which enhances the capability to simulate systems related to off-gas treatment, has been demonstrated for a range of real-gas systems in the literature and is ready for testing with data currently being collected for multicomponent systems of interest, including iodine and water on MS3A. A diffusion kinetic model for sorbent pellets involving pore and surface diffusion as well as external mass transfer has been established, and a methodology was developed for determining unknown diffusivity parameters from transient

  16. Delayed hydride cracking behavior for zircaloy-2 plate

    International Nuclear Information System (INIS)

    Mills, J.W.; Huang, F.H.

    1991-01-01

    The delayed hydride cracking (DHC) behaviour for Zircaloy-2 plate was characterized at temperatures ranging from 300 to 550 o F. Specimens with a longitudinal (T-L) orientation exhibited a classic two-stage DHC response. At K values slightly above the threshold level (K th ), crack-growth rates increased dramatically with increasing K values (stage I). The K th value was found to be 11 and 14 ksi√ in at 400 and 500 o F. At high K values (stage II), cracking rates were relatively insensitive to applied K levels. Stage II crack growth was a thermally activated process described by an Arrhenius-type relationship with an activation energy of 65 kJ/mol. This energy level agreed with the theoretical activation energy for hydrogen diffusion into the triaxial stress field ahead of a crack. Above a critical temperature (300 o F), an overtemperature cycle was required to initiate DHC. The magnitude of the thermal excursion required to initiate cracking was found to increase at higher test temperatures. Specimens with a transverse(L-T) orientation showed a very low sensitivity to DHC because of an unfavorable crystallographic orientation for hydride reorientation. Metallographic and fractographic examinations were performed to understand the DHC mechanism. (author)

  17. Production of hydrogen gas from novel chemical hydrides

    Energy Technology Data Exchange (ETDEWEB)

    Aiello, R.; Matthews, M.A. [South Carolina Univ., Chemical Engineering Dept., Columbia, SC (United States); Reger, D.L.; Collins, J.E. [South Carolina Univ., Chemistry and Biochemistry Dept., Columbia, SC (United States)

    1998-12-01

    Six ligand-stabilized complexes have been synthesized and tested for use as hydrogen storage media for portable fuel cell applications. The new hydrides are: [HC(3,5-Me{sub 2}pz){sub 3}]LiBH{sub 4} (1), [[H{sub 2}C(3,5-Me{sub 2}pz){sub 2}]LiBH{sub 4})]{sub 2} (2) (pz = pyrazolyl), [(TMEDA)Li(BH{sub 4})]{sub 2} (3) (TMEDA (CH{sub 3}){sub 2}NCH{sub 2}CH{sub 2}N(CH{sub 3}){sub 2}), [HC(pz){sub 3}]LiBH{sub 4} (4), [[H{sub 2}C(pz){sub 2}]Li(BH{sub 4})]{sub 2} (5) and Mg(BH{sub 4}){sub 2}3THF (6) (THF = tetrahydrofuran). Hydrolysis reactions of the compounds liberate hydrogen in quantities which range from 56 to 104 ({+-}5%) of the theoretical yield. Gas chromatographic analysis of the product gases from these reactions indicate that hydrogen is the only gas produced. Thermally initiated reactions of the novel compounds with NH{sub 4}Cl were unsuccessful. Although the amount of hydrogen energy which can be theoretically obtained per unit weight is lower than that of the classical hydrides such as LiBH{sub 4} and NaBH{sub 4}, the reactions are less violent and hydrolysis of compounds 1, 2, 4, 5 and 6 releases less heat per mole of hydrogen generated. (Author)

  18. Electron and nuclear magnetic resonances in compounds and metallic hydrides

    International Nuclear Information System (INIS)

    Brasil Filho, N.

    1985-11-01

    Proton pulsed Nuclear Magnetic Resonance measurements were performed on the metallic hydrides ZrCr 2 H x (x = 2, 3, 4) and ZrV 2 H y (y = 2, 3, 4, 5) as a function of temperature between 180 and 400K. The ultimate aim was the investigation of the relaxation mechanisms in these systems by means of the measurement of both the proton ( 1 H) spin-lattice (T 1 ) and spin-spin (T 2 ) relaxation times and to use these data to obtain information about the diffusive motion of the hydrogen atoms. The diffusional activation energies, the jump frequencies and the Korringa constant, C k , related with the conduction electron contribution to the 1 H relaxation were determined for the above hydrides as a function of hydrogen concentration. Our results were analysed in terms of the relaxation models described by Bloembergen, Purcell and Pound (BPP model) and by Torrey. The Korringa type relaxation due to the conduction electrons in metallic systems was also used to interpret the experimental results. We also present the Electron Paramagnetic Ressonance (EPR) study of Gd 3+ , Nd 3+ and Er 3+ ions as impurities in several AB 3 intermetallic compounds where A = LA, Ce, Y, Sc, Th, Zr and B = Rh, Ir, Pt. The results were analysed in terms of the multiband model previously suggested to explain the behaviour of the resonance parameter in AB 2 Laves Phase compounds. (author) [pt

  19. Theoretical study of hydrogen storage in metal hydrides.

    Science.gov (United States)

    Oliveira, Alyson C M; Pavão, A C

    2018-05-04

    Adsorption, absorption and desorption energies and other properties of hydrogen storage in palladium and in the metal hydrides AlH 3 , MgH 2 , Mg(BH 4 ) 2 , Mg(BH 4 )(NH 2 ) and LiNH 2 were analyzed. The DFT calculations on cluster models show that, at a low concentration, the hydrogen atom remains adsorbed in a stable state near the palladium surface. By increasing the hydrogen concentration, the tetrahedral and the octahedral sites are sequentially occupied. In the α phase the tetrahedral site releases hydrogen more easily than at the octahedral sites, but the opposite occurs in the β phase. Among the hydrides, Mg(BH 4 ) 2 shows the highest values for both absorption and desorption energies. The absorption energy of LiNH 2 is higher than that of the palladium, but its desorption energy is too high, a recurrent problem of the materials that have been considered for hydrogen storage. The release of hydrogen, however, can be favored by using transition metals in the material structure, as demonstrated here by doping MgH 2 with 3d and 4d-transition metals to reduce the hydrogen atomic charge and the desorption energy.

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

    International Nuclear Information System (INIS)

    Matin, M.R.

    2009-01-01

    'Full text': Ammonia borane (NH 3 BH 3 ) has been of great interest owing to its ideal combination of low molecular weight and high H 2 storage capacity of 19.6 mass %, which exceeds the current capacity of gasoline. DOE's year 2015 targets involve gravimetric as well as volumetric energy densities. In this work, we have investigated thermal decomposition of ammonia borane and calcium hydride composites at different molar ratio. The samples were prepared by planetary ball milling under hydrogen gas atmosphere pressure of 1Mpa at room temperature for 2, and 10 hours. The gas desorption properties were examined by thermal desorption mass spectroscopy (TDMS). The identification of phases was carried out by X-ray diffraction. The results obtain were shown in fig (a),(b),and (c). Hydrogen desorption properties were observed at all molar ratios, but the desorption temperature is significantly lower at around 70 o C at molar ratio 1:1 as shown in fig (c), and unwanted gas (ammonia) emissions were remarkably suppressed by mixing with the calcium hydride. (author)