Masanori HARA, Masao MATSUYAMA, Kan ASHIDA, Yuji HATANO, Munekazu KAGO,Kuniaki WATANABE
Hydrogen Isotope Research Center, Toyama University, Gofuku 3190, Toyama 930-8555, Japan

Abstract
　A tritium experimental system for 100 Ci/run was established at the Hydrogen Isotope Research Center, Toyama University. The system has two distinct experimental chambers: a tritium circulation system and an exhaust-gas detritiation device. The former consists of tritium storage, purification and gas chromatographic hydrogen isotope separation units. The performance of the isotope separation unit was examined for 20 Pa⋅l, a sample gas mixture containing protium, deuterium and tritium under the conditions of operation temperature at 77 K and carrier-gas (Ne) flow of 50 cc/min. Six isotope compounds of hydrogen were reproducibly separated within an adequate period of time (within 5000 seconds). In addition, the relative sensitivities of the thermal conductivity detector could be determined in-situ with the aid of an ionization chamber for detecting tritiated hydrogen isotope molecules.

J. L. Wan, M. Hara, Y. Jin and K. Watanabe
Hydrogen Isotope Res. Centr., Toyama Univ., Gofuku 3190, Toyama 930-8555, Japan

Abstract
　The kinetics of hydrogen absorption by a Pd-4 at%Pt alloy was studied in the temperature range of 0 to 80 C and pressure from 0.1 to 10 Torr by using a vacuum microbalance. The absorption kinetics extending over the entire absorption curve be analyzed by a diffusion model assuming notable contributions from dissociative adsorption of hydrogen molecules and associative desorption of adsorbed hydrogen atoms on the surface. The activation energies for absorption and desorption were determined to be 4.6 and 9.0 kcal/mol (H₂), respectively. Based on these values, the heat of the hydrogen solution was evaluated to be -4.6 kcal/mol (H₂), which is in good agreement with the value obtained by thermodynamic study. In addition, the activation energy for diffusion was determined to be 7.1 kcal/mol (H), causing slower hydrogen diffusion in the alloy than Pd.

Yuji Hatano, Tomoyuki Tachikawa, Daobin Mu, Takayuki Abe, Kuniaki Watanabe and Shotaro Morozumi
Hydrogen Isotope Research Center, Toyama University, Toyama 930-8555, JAPAN

Abstract
　An amorphous MgNi alloy was prepared by mechanical alloying, and its charge/discharge characteristics were examined in a 6 M KOH solution at room temperature. The discharge capacity of the alloy was large than that of conventional AB₅ alloys in the initial stage of charge/discharge cycles, but it decreased promptly with an increase in cycle number. The cell voltage in the charge process increased with the cycles. Degradation in the discharge capacity also occurred owing to immersion in the KOH solution under an open circuit potential. Since the formation of a Mg(OH)₂ layer was observed by X-ray diffraction analysis, the degradation of the electrode was ascribed to the increase in overvoltage in the charge process by the Mg(OH)₂ layer formed on the alloy surface through the chemical reaction between the alloy and the KOH solution. The effect of heat treatment on the charge/discharge characteristics was also examined. The discharge capacity of amorphous MgNi and MgNi_0.6Co_0.4 alloys decreased in the initial stage of the cycle test by heating in argon owing to recrystallization. The degradation rates of these alloys, however, were also reduced by heating at 300℃, and the heated alloys showed large discharge capacity compared with unheated ones after 10 cycles. These results were attributed to the increase in surface area of the alloys brought about by selective evaporation of magnesium.

Masao MATSUYAMA, Satoshi UEDA and Kuniaki WATANABE
Hydrogen Isotope Research Center, Toyama University, Gofuku 3190, Toyama 930-8555, Japan

Abstract
　The usefulness of the recently developed β-ray-induced x-ray spectrometry (BIXS) for nondestructive measurements of tritium captured in matrix was investigated using zirconium as a model sample. Two distinct spectra from characteristic and bremsstrahlung x-rays were clearly observed for the Zr sample exposed to tritium gas at room temperature. The former x-rays showed a sharp intense peak, while the latter x-rays formed a broad continuous spectrum. The intensity of both peaks decreased sharply with vacuum heating. At the same time, the top of the bremsstrahlung x-ray peak shifted to the higher energy side. These results indicate that the absorbed tritium diffused into the bulk by heating in vacuo. The changes were analyzed by computer simulation. The computer simulation could reproduce the observed spectra quite well. BIXS is therefore thought to be a highly promising technique for nondestructive determination of tritium inventories and depth profiles in materials.

K. Fujino^*, K. Ashida, K. Watanabe, T. Okabe^*
Hydrogen Isotope Res. Centr.,
*Faculty of Science, Toyama Univ., Gofuku 3190, Toyama 930-8555, Japan

Abstract
　Interest has recently been shown in amorphous carbon films from the viewpoint of fuel recycling and inventory in magnetically confined fusion devices. In this study, amorphous carbon films were prepared on silicon substrates by RF discharge of methane and ethylene, and they were characterized by gas analysis and FR-IR and Raman spectroscopies. The results of gas analysis showed that the carbon film prepared by methane (a-C/CH₄₎ contained a larger amount of hydrogen than that by ethylene (a-C/C₂H₄) ; the hydrogen-to-carbon rations in the films, [H]/[C], were evaluated to be 1.84 and 1.40 for a-C/CH₄ and a-C/C₂H₄, respectively. The FT-IR and Raman spectroscopies showed that the films consisted of a carbon framework comprised of C-C and C=C bonds, but the fraction of C=C contained in the a-C/CH₄ film was smaller than that in the a-C/C₂H₄ film. It was concluded that the difference in the hydrogen contents was mainly due to the difference in the relative contents of these bonds in the films.

Ryo HAYAKAWA, Yuji HATANO and Kuniaki WATANABE
Hydrogen Isotope Research Center, Toyama University, Gofuku 3190, Toyama 930-8555, Japan

Abstract
　Temperature dependence of hydrogen permeation rate was examined for a vanadium membrane oxidized at room temperature by exposure to air. Pressure dependence of the permeation rate was also examined to determine the rate-controlling process of the permeation. The change in the chemical state of surface oxide by heating in vacuum was analyzed by X-ray photoelectron spectroscopy (XPS). The permeation rate was small below 300℃ and significantly increased in the temperature range from 300 to 400℃. The rate-controlling process of the permeation was determined as surface reaction because the permeation rate increased in proportion to the upstream pressure. A surface oxide film consisting of V₂O₃ and VO was formed on the vanadium surface. At almost the same temperature at which the permeation rate increased, V₂O₃ and VO were reduced to metal. Hence, the increase in permeation rate at a temperature above 300℃ was ascribed to the reduction of V₂O₃ and VO to metal. The reduction of V₂O₃ to metal took place via VO.

Yoshiaki FUTAMURA
Hydrogen Isotope Research Center, Toyama University, Gofuku 3190, Toyama 930-8555, JAPAN
Hiroshi KAWAMURA^* and Kunihiko TSUCHIYA^*
*Japan Atomic Energy Research Institute, Shinbori 3607, Narita-cho,Oarai-machi, Higashi-Ibaragi
Gun, Ibaragi 311-1394, JAPAN

Abstract
　This up-to-date compilation of data for ceramic breeding materials (Li₂O, Li₂TiO₃, Li₂ZrO₃, and Li₄SiO₄) is part of a study to construct a database for tritium breeding materials of fusion reactor blankets in which existing data for breeding materials and neutron multipliers have been collected from as many sources possible.
 The data compiled include data on physical and thermal properties, mechanical properties, chemical stability and compatibility, tritium solubility and transport, irradiation effects, afterheat characteristics, thermal cycling effects, waste disposal, and other miscellaneous properties of ceramic breeding materials, such as Li₂O, Li₂TiO₃, Li₂ZrO₃, and Li₄SiO₄. As a result of this compilation, the status of existing data can be recognized.