Behavior Of Hydrogen Isotopes Research Articles

Breakthrough Curve Analysis of Pressure Swing Adsorption for Hydrogen Isotope Separation

For the purpose of developing an effective system for hydrogen isotope separation, we have been studying the adsorption-desorption dynamic behavior of hydrogen and deuterium in a packed-bed column with synthetic zeolites, aimed at applying the pressure swing adsorption process. The adsorption behavior of molecules in the packed-bed is reflected in the breakthrough curves. To understand the characteristic behaviors of hydrogen isotopes in the packed-bed, we carried out breakthrough experiments in a conventional adsorption process and in a practical process following sequential processes alternating between adsorption and desorption. From the former experiments, the results were obtained that the overall mass transfer was influenced by longitudinal dispersion relating to the superficial velocity and that the process governing the mass transfer within adsorbents was diffusion in the macro-pores of pellets. In the latter experiments, unique profile breakthrough curves were observed. These curves can be described with the numerical simulation assuming the initial distributions in a packed-bed.

Helium Implantation Effects on Retention Behavior of Hydrogen Isotopes in Oxygen-Contained Boron Films

He+ implantation effects on the Retention behavior of hydrogen isotopes implanted into 35% oxygen-contained boron film was studied by means of SEM, AFM, XPS and TDS. It was found that the D retention for only D2+ implanted film was the highest and it decreased for pre-He+ implanted film and post-He+ implanted film. From the SEM and AFM images, the surface morphology of the oxygen-contained boron film was partly cracked, indicating that B2O3 was formed in the film. From the TDS and XPS results, the defective structure and the formation of B-D-B bond, B-D bond and B-O-D bond were observed by He+ and D2+ implantation, respectively. It was suggested that oxygen was trapped as B-O bond. The reaction with implanted D2+ was preceded in different mechanism.

Hydrogen isotope behavior and its interaction with post irradiated energetic helium in SiC

The D2 + was irradiated into SiC up to the saturation and thereafter He+ irradiation was performed to elucidate interaction mechanism between hydrogen isotope retained in SiC and irradiated energetic He+ by means of X-ray photoelectron spectroscopy (XPS) and thermal desorption spectroscopy (TDS). It was found that D was trapped by both of Si and C by D2 + irradiation and only D bound to Si interacted with irradiated He+ in the initial He+ irradiation stage. Some damaged structures were introduced into SiC by both of D2 + and He+ irradiation. By heating after the irradiation experiments, most of SiC structure was recovered at the temperature above 1000 K. However, some free C was migrated toward the surface and aggregated on the surface of SiC. This fact indicates that the C impurity would contaminate the plasma and/or the tritium breeding materials, which is thought to be contacted with the SiC inserts.

Hydrogen isotope behavior in the first wall of JT-60U after deuterium plasma operation

Retention of hydrogen isotopes in the carbon (isotropic graphite) first wall tiles of JT-60U was studied by secondary ion mass spectrometry and thermal desorption spectroscopy. The surface morphology and erosion/deposition profiles of the tiles were characterized using scanning electron microscope and X-ray photoelectron spectroscopy. The upper area is mainly eroded, while the bottom area of the inboard wall is dominated by deposition. In contrast to the divertor area, hydrogen isotope retention in the eroded wall area was generally larger than that in the deposition dominated area. Measured near surface concentrations of hydrogen isotopes in the wall tiles, as well as the D/H ratios, were a little higher than those in the divertor area. This indicates direct implantation of high-energy D from NBI into the first wall. The lower temperature of the first wall relative to the divertor tiles would reduce desorption and/or replacement of implanted D by subsequent D or H impingement.

Review of advances in development of vanadium alloys and MHD insulator coatings

Recent progress in the development of low activation vanadium alloys and MHD insulator coatings for a Li-self cooled blanket is reviewed. Research progress in vanadium alloys is highlighted by technology for fabricating creep tubes, comparison of thermal creep in vacuum and Li, understanding impurity transfer between vanadium alloys and Li and its impact on mechanical properties, behavior of hydrogen and hydrogen isotopes, low dose irradiation effects on weld joints, and exploration for advanced vanadium alloys. Major remaining issues for vanadium alloys are thermal and irradiation creep, helium effects on high-temperature mechanical properties and radiation effects on low-temperature fracture properties. Er 2O 3 showed good compatibility with Li, and is promising as a MHD insulator coating on vanadium alloys. Significant progress in coating technology for this material has been made. Recent efforts are focused on multi-layer and in-situ coatings. Tests under flowing lithium conditions with a temperature gradient are necessary for quantitative examination of coating performance.

Selective release of D and 13C from insoluble organic matter of the Murchison meteorite by impact shock

Abstract— We performed shock‐recovery experiments on insoluble organic matter (IOM) purified from the Murchison meteorite, and determined the abundances and isotope ratios of hydrogen and carbon in the shocked IOM sample. We also performed shock experiments on type III kerogen and compared the results of these experiments with the experimental results regarding IOM.The shock selectively released D and 13C from the IOM, while it preferably released H and 12C from the kerogen. The release of these elements from IOM cannot be explained in terms of the isotope effect, whereas their release from kerogen can be explained by this effect. The selective release of heavier isotopes from IOM would be due to its structure, in which D and 13C‐enriched parts are present as an inhomogeneity and are weakly attached to the main network. Shock gave rise to a high release of D even at a lower degree of dehydrogenation compared with the stepwise heating of IOM. This effective release of D is probably an inherent result of shock, in which a dynamic high‐pressure and high‐temperature condition prevails. Thus, shock would effectively control the hydrogen isotope behavior of extraterrestrial organic matter during the evolution of the solar nebula.

Measurement of the transport of hydrogen isotopes near the surface of metal-hydride and deuteride using elastic recoil detection technique

The thermal behavior of hydrogen isotopes near the surface of δ-phase titanium hydride and deuteride covered with an oxide layer has been investigated using the elastic recoil detection (ERD) technique. The hydrogen isotopes concentrations near to the surface of the hydride and deuteride decreased exponentially as a function of annealing time in the temperature range of 423–488K. Also a hydrogen concentration gradient is formed at the surface. The change of the hydrogen distribution with annealing time at several temperatures was analyzed using mass balance equations in which elementary processes such as diffusion, trapping and detrapping at vacant trap sites are taken into account. The effective diffusion rates of hydrogen isotopes to the topmost oxide layer and thermal detrapping rates of hydrogen isotopes at the hydride–oxide interface were estimated. Moreover, the activation energies for the effective diffusion rate and the thermal detrapping rate were determined to be 0.54±0.10 and 1.20±0.02eV, respectively.

Dynamic observation of the behavior of 3 keV [formula omitted] irradiated into Li 2O using IR absorption spectroscopy

In order to understand the influence of radiation defects on hydrogen isotope behavior in Li 2O, an in situ IR absorption analysis was carried out during 3 keV D 2 + irradiation. Three IR absorption peaks were obtained from the stretching vibrations of O–Ds in different existence states: an O–D existing as a LiOD phase at 2710 cm −1, a surface O–D with several adjacent O–Ds at 2660 cm −1, and an O–D affected by a defect in the bulk at 2605 cm −1. At the outset of the irradiation, only the surface O–D appeared. As the ion fluence increased, the O–D affected by a defect started to form in the bulk, and the LiOD phase followed it. The defect related with the O–D at 2605 cm −1 was regarded as a Li vacancy. It was indicated that the hydrogen isotopes were stabilized in Li 2O through an interaction with the Li vacancy (LiO −–D +: 2605 cm −1) or mutual aggregation (LiOD phase: 2710 cm −1).

Thermal desorption behavior of hydrogen isotopes interacting with radiation defects in Li 2O

In order to understand the influence of radiation defects on hydrogen isotope behavior in Li 2O, thermal desorption spectroscopy (TDS) was applied to single-crystal samples into which deuterium had been introduced by two different methods: deuterium ion irradiation or deuterium thermal absorption. In both cases, a sharp peak of water species was observed at 680 K due to the decomposition of the LiOD phase. Additionally, two desorption peaks, one corresponding to HDO at 870 K and the other to HD/D 2 at 900 K, were found for the irradiated sample. A comparison with the literature regarding these two desorption peaks at this stage suggested that the former desorption was due to D + diffusing in the bulk, while the latter was due to D − trapped by the F 0 centers or the deuterium bubbles.

Hydrogen Isotope Behavior in Type 316 Stainless Steel Sorbed by Various Methods

Typical materials for components, type 316 stainless steel (316-SS), were chosen as a sample and hydrogen isotope was charged by various methods, water adsorption, electrolysis and ion irradiation to elucidate hydrogen isotope behavior on/in SS. The chemical states of SS surface were studied by XPS and the hydrogen isotope retention and its desorption behavior were analyzed by TDS. Two types of surface finish, namely non-pretreated sample and pretreated sample by polish and annealing were prepared. It was found that the oxy-hydroxide and hydroxide were formed on the surface layer. The hydrogen isotope desorption stages consisted of three stages, namely the desorption stages from oxy-hydroxide, hydroxide and bulk hydrogen. A large amount of deuterium was trapped by the oxy-hydroxide layer for the non-pretreated sample with electrolysis. The hydrogen isotope trapping by this layer would have a large influence on the hydrogen isotope retention. The surface finish would be one of the effective improvement for decreasing its retention on SS.

Release Behavior of Hydrogen Isotopes from JT-60U Graphite Tiles

Release behavior of hydrogen isotopes from the graphite tiles used in JT-60U was observed using the thermal desorption method where temperature was stepwise elevated to 300, 600 and 1000 °C. When first wall tile was left under helium atmosphere at 600 °C for 8 hours, about 40 % of total amount of hydrogen and deuterium retained in the tile was released, although only a small amount of hydrogen isotopes was released at 300 °C, which is the base temperature of inner wall of JT-60U. This indicates that a higher temperature of inner wall causes hydrogen retention to reduce considerably. When the graphite tiles were exposed to hydrogen at 1000 °C, the release of deuterium and tritium was enhanced. It is considered that the deuterium and tritium left in the graphite tile was released by the isotope exchange reaction. In order to remove almost all deuterium or tritium from the graphite tile without combustion of graphite, isotope exchange method at high temperature is effective. It was found that the amount of hydrogen retained in the graphite tile was much larger than that of deuterium. This indicates that a large amount of deuterium trapped in the tiles during deuterium discharge experiments was replaced with hydrogen during hydrogen discharge experiments. Additionally, depth profiles of hydrogen isotope are discussed from the obtained release curves.

Multi-Component Adsorption Behavior of Hydrogen Isotopes on Zeolite 5A and 13X at 77.4 K

Equilibrium isotherms for the adsorption of H2, HD, HT, D2, DT and T2 on synthetic zeolite type 5A or 13X at 77.4 K are estimated by using a theoretical formula, where the isotopic difference in adsorption depends on the zero-point energy difference between hydrogen isotopes. The formula agrees with the experimental isotherms for H2 and D2 on the zeolites. Adsorption of H2-D2 and H2-HD-D2 mixtures on the same adsorbents is experimentally examined. The experiments are performed using a volumetric apparatus and a quadra-pole-type mass spectrograph. The experimental adsorption behavior of H2, D2 and HD shows agreement of separation factors with results calculated according to the ideal adsorbed solution theory describing multi-component behavior, where the equilibrium isotherms estimated for H2, HD and D2 are used. Based on the theoretical adsorption model, the multi-component behavior of HT, DT and T2 is predicted here.

ステンレス(SS-316)材料表面における水素同位体挙動の解明

ステンレス(SS-316)材料表面における水素同位体挙動の解明

Hydrogen and Oxygen Isotope Constraints on Hydrothermal Alteration of the Trinity Peridotite, Klamath Mountains, California

The Trinity peridotite represents a rare opportunity to examine a relatively fertile plagioclase peridotite that was exhumed and later subjected to intrusive events in a seafloor environment, followed by its emplacement and incorporation into a continent. Over 250 stable isotopic determinations on whole rocks and minerals elucidate the hydrothermal evolution of the Trinity complex. All three serpentine polymorphs are present in the Trinity peridotite; these separate on the basis of their δD values: antigorite, -46 < δD < -82‰ and lizardite and chrysotile, -90 < δD < -106 and -110 < δD < -136‰, respectively. Antigorite coexists with chlorite, talc, and tremolite in contact aureole assemblages associated with Silurian/Devonian gabbroic plutons. Lizardite and chrysotile alteration carries a meteoric signature, which suggests association with post-emplacement serpentinization, or overprinting of earlier low-temperature seafloor serpentinization. Regionally, contours of δD values exhibit bull's-eye patterns associated with the gabbroic plutons, with δD maxima coinciding with the blackwall alteration at the margins on the plutons. In contrast to the hydrogen isotope behavior, oxygen isotope values of the three polymorphs are indistinguishable, spanning the range 5.3 < δ18O< 7.5, and suggesting low integrated fluid fluxes and strongly 18O-shifted fluids. Inferred primary δ18O values for peridotite, gabbro, and late Mesozoic granodiorite indicate a progressive 18O enrichment with time for the source regions of the rocks. These isotopic signatures are consistent with the geology, petrochemistry, and geochronology of the Trinity massif, which indicate the following history: (1) lithospheric emplacement and cooling of the peridotite in an oceanic environment ~472 Ma; (2) intrusion of gabbroic plutons into cold peridotite in an arc environment between 435 and 404 Ma; and finally (3) intrusion of felsic plutons between 171 and 127 Ma, long after the peridotite was incorporated into the continental crust.

Hydrogen Isotope Behavior in Type 316 Stainless Steel Sorbed by Various Methods

Hydrogen Isotope Behavior in Type 316 Stainless Steel Sorbed by Various Methods

Multi-Component Adsorption Behavior of Hydrogen Isotopes on Zeolite 5A and 13X at 77.4 K

Multi-Component Adsorption Behavior of Hydrogen Isotopes on Zeolite 5A and 13X at 77.4 K

Depth Profile Measurements of Hydrogen Isotopes near the Surface of the TFTR Plasma Facing Component using Nuclear Reaction Analysis

Tritium and deuterium depth profiles of the TFTR tile exposed to deuterium-tritium plasmas have been measured to reveal the hydrogen isotope behavior at the surface region by means of deuteron induced nuclear reaction analysis. The analyzed sample was a part of a tile made of a four-dimensional carbon fiber composite, which was placed at K bay, column C, row 16 of the TFTR vacuum vessel. Four kinds of elements, deuterium, tritium, lithium -6 and lithium -7, were identified. The tritium concentration had a peak at 0.5 μm with an atomic density of 7.4×1025 T/m3 in depth profile, whereas the deuterium showed a broad distribution up to the depth of 1.5 μm with atomic densities of 3.4×1027 D/m3. It is found that a fraction of the retained tritium from the surface to 1.5 μm, 8.1×1019 T/m2, corresponded to 2% of that from the surface to 1 mm, 1.0×1021 T/m2, which was measured for the KC-18 tile using the combustion method.

Retention characteristics of hydrogen isotopes in JT-60U

Erosion/deposition distribution and hydrogen isotope behavior in the JT-60U plasma-facing wall were investigated. Distribution of the tritium, which was produced by D–D nuclear reaction, was not correlated with erosion/deposition distribution. The tritium distribution can be explained by the distribution of high-energy tritium ion-implantation due to ripple loss. Deuterium distribution in the divertor region was different from the tritium distribution and not well correlated with the deposition. The highest D/C was ∼0.05 at the bottom of the outer dome wing, which is much less than that observed in other tokamaks. For the deuterium retention, at least two retention processes (ion-implantation and co-deposition) were found on the dome region. The systematic dust collection gave the small amount of dust (∼7g: 0.2mg/s production) in the whole vessel of JT-60U. Deposition was observed at the remote area of the outer divertor region.

Dynamic hydrogen isotope behavior and its chemical states in SiC by XPS and TDS technique

Deuterium ions were implanted into SiC to elucidate the interaction mechanism between deuterium and SiC. The chemical states of Si and C were studied by X-ray photoelectron spectroscopy (XPS) and thermal desorption behavior of deuterium was analyzed by thermal desorption spectroscopy (TDS). It was found that the peak energies of C1s and Si2p by XPS were, respectively, shifted to higher and lower binding energy side by the deuterium ion irradiation. These results indicate that the deuterium was trapped by Si and C. In the TDS analysis, two desorption peaks were observed at around 800K and 1000K, respectively. These results show that the low temperature stage was induced by the deuterium bound to C and the high temperature stage corresponded to the desorption of deuterium bound to Si, respectively. The hydrogen isotope trapping mechanism was discussed by taking account of the reported quantum chemical analyses.

Implanted hydrogen isotope retention and chemical behavior in boron thin films for wall conditioning

The behavior of hydrogen isotopes in boron was studied by XPS and TDS. The samples used were boron polycrystals and boron thin films produced by plasma CVD using decaborane (B 10H 14) diluted by He gas. The 1.0 keV deuterium ions were implanted into the samples up to fluence of 5.4 × 10 21 D m −2 at various temperatures. It was found that deuterium retention at 573 K was decreased less than 35% compared to that at room temperature. The activation energies for B–D–B and B–D bonds were estimated to be 1.11 ± 0.21 and 2.17 ± 0.36 eV for the boron thin film, and 1.36 ± 0.20 and 2.27 ± 0.45 eV for the boron polycrystal, respectively. The B–H distance and the activation energy for the B–H bond were also calculated by the Gaussian 03 code and these were consistent with the experimental values.