Kazuo Furukawa
Japan Atomic Energy Research Institute
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Featured researches published by Kazuo Furukawa.
Journal of Physics and Chemistry of Solids | 1982
Hiroji Katsuta; Rex B. McLellan; Kazuo Furukawa
Abstract The permeability and diffusivity of hydrogen in molybdenum was measured by the time-lag method using molybdenum membranes prepared by electron beam melting and cleaned by argon ion etching. Measurements were also made on membranes prepared in this manner and subsequently coated with palladium. The inconsistencies in the previous data, a consequence of surface effects, have been clarified. The activation energy for H-diffusion in Mo is 10.6 KJ/mol.
Journal of Nuclear Science and Technology | 1981
Hiroji Katsuta; Kazuo Furukawa
The permeation time-lag method have been used to determine the permeabilities, diffusion coefficients and solubilities of hydrogen and deuterium in type 304 stainless steel of three kinds of surface treated specimens; with oxide film, reduced by H2 gas and Pd coated. For the specimen with a thin oxide film the permeability increased abruptly at the temperature higher than 1,050 K owing to reduction of the oxide film by H2 gas introduced. The permeability and diffusion coefficient for hydrogen-reduced specimens agreed with those for Pd-coated specimens showing the data of bulk diffusion limited. The isotope effects for permeability ΦH/ΦD, diffusion coefficient D H/D D and solubility were about 1.4, 1.2 and 1.1, respectively. From these values θ(=hν/k)=1,530±50K and θ′(=hν/k)=2,740±20K were obtained by the quantum effect of a harmonic approximation.
Journal of Nuclear Materials | 1981
Satoru Tanaka; Hiroji Katsuta; Kazuo Furukawa; Ryohei Kiyose
Abstract Hydrogen permeation through niobium membrane contacting with liquid lithium was experimented using natural convection type loop containing about one kilogram of lithium. Disk type niobium membrane (0.02 cm thick and 5.8 cm 2 in area) which was welded to a tube was inserted into liquid lithium and permeation constant was obtained from the hydrogen pressure change in the tube after it was disconnected from a vacuum line. Hydrogen permeation constant was smaller by about two orders of magnitude than in the ideal case when diffusion in metal is rate-determining. This is considered to be caused by the layer of niobium nitride (Nb 2 N) which formed on the lithium side surface of the niobium membrane. Changes of hydrogen permeation constants with hydrogen concentration in lithium were studied and hydrogen permeation rate was considered to have a linear relationship with hydrogen pressure. In the next step of our experiments, nitrogen in lithium was gettered by titanium in which case the hydrogen permeation constant became several times larger than in not gettered lithium. Nitrogen transport from niobium surface was however a slow reaction and there would be a limitation of the reaction as well as permeation resistance of oxide film at the gas side.
Journal of the Chemical Society, Faraday Transactions | 1981
Hideo Ohno; Kazuo Furukawa
The first peak position in the radial distribution curve g(r) of molten NaCl was obtained as 2.73 A by an X-ray diffraction analysis, which was consistent with that of Zarzycki. Therefore, the first peak position in g(r), 2.6 A, obtained by neutron diffraction has too low a value and cannot be used as evidence of coincidence with the computer-simulation calculations.
Journal of the Chemical Society, Faraday Transactions | 1981
Hideki Morikawa; Michihiro Miyake; Shin-ichi Iwai; Kazuo Furukawa; A. Revcolevschi
The structure of molten V2O5 has been investigated using a radial distribution function based on X-ray scattered intensity data collected at 750 °C; analysis was by the correlation method. The average V—O distance of 1.75 A in the melt is shorter than that of 1.82 A in the crystal and the coordination number of 3.9 in the melt is smaller than that of 5.0 in the crystal. The most probable model for molten V2O5 is similar to the crystal structure of P2O5 or SiO2. Each VO4 tetrahedron is surrounded by three VO4 tetrahedra and the V—V distance of 3.44 A is almost equal to twice the V—O distance. The estimated density of the model assuming the cristoballite-like structure is 2.4 g cm–3, while the measured density is 2.15 g cm–3.
Journal of the Chemical Society, Faraday Transactions | 1978
Hideo Ohno; Kazuo Furukawa
The structures of molten LiNO3, NaNO3, KNO3, RbNO3, CsNO3 and AgNO3 have been investigated by deriving the radial distribution function from X-ray diffraction data. The existence of NO–3 ions in these molten salts was confirmed by analysis of the first peaks of the radial distribution functions. Nitrate ions and cations could have a diamond (or zinc blende)-like arrangement with 25 % random vacancies in molten NaNO3, KNO3, RbNO3 and CsNO3. On the other hand, nitrate ions and cations could have a simple cubic (or NaCl)-like arrangement in molten AgNO3 and LiNO3.
Journal of Nuclear Materials | 1971
Hitoshi Watanabe; T. Kurasawa; Takeo Kikuchi; Kazuo Furukawa; I. Nihei
A reaction on the surface of hyperstoichiometric UC exposed to purified sodium (estimated < 1 ppm O) for 500 to 2000 h at the temperature of 700 °C has been metallographically studied using the apparatus designed for studying compatibility. The rate of decarburization was 2 × 10−4mm/h for arc cast carbides and 1 × 10−4mm/h for sintered carbides. It becomes evident that the decarburization in the hyperstoichiometric UC is controlled by dissolution of carbon in the UC2 phase which comes in contact with sodium penetrating through the crevices produced during the depletion of the UC2 phase. In contrast to the arc cast carbide which was decarburized 410 μm in thickness after the exposure time of 2000 h, the carbide of the identical carbon content which mainly consisted of the U2C3 phase transformed by heat treatment was decarburized only 3 μm in thickness under the same exposure condition.
Journal of the Chemical Society, Faraday Transactions | 1978
Hideo Ohno; Mitsugu Yoroki; Kazuo Furukawa; Yoshiki Takagi; Tetsuro Nakamura
The molten structure of PbCl2, LiCl and their mixtures were examined by X-ray diffraction analysis. In molten Pbcl2, each Pb atom is surrounded by about eight Cl atoms at a distance of 2.92 A, which is near to the sum of the ionic radii of Pb2+ and Cl–. It is expected that only very few rigid complex anions will be present in molten PbCl2. The results of X-ray diffraction analysis in molten PbCl2 are consistent with those of Raman spectroscopy. The average Pb–Pb interaction in the molten state should be intermediate between a b.c.c. and an s.c. arrangement and the s.c. arrangement takes precedence with increasing LiCl concentration.
Journal of Nuclear Materials | 1977
Hiroji Katsuta; Kazuo Furukawa
Abstract The effects of nonmetallic impurities on the compatibility of liquid lithium with molybdenum, TZM, niobium, type 304 and type 316 stainless steels, nickel and Hastelloy N were investigated. Three compatibility tests (test I, test II and test III), classified by the grade of air contamination of the lithium, were conducted at 600°C for about 1000 h in stainless-steel vessels. In each test the above-mentioned specimens were immersed together in the lithium. In test I weight gain was observed for all the specimens except nickel and Hastelloy N. However, in test II and test III, weight loss was observed for all the specimens. MoNi 3 was produced on the surface of the molybdenum and TZM specimens as a result of the reaction between molybdenum and nickel dissolved in the liquid lithium. NbN 0.9 O 0.1 was observed on the surface of niobium specimens in test I and test II, and Nb 2 N in test II and test III. The surface of the stainless-steel specimens in test II and test III was depleted with nickel and chromium elements, and deteriorated. The corrosion rates of the test specimens in test III were about 2, 5, 26 and 22 μm/yr for molybdenum or TZM, niobium, type 304 stainless steel and type 316, respectively. Nickel and Hastelloy N were severely attacked by liquid lithium at 600°C. These results were obtained for liquid lithium with a high nickel concentration.
Archive | 2011
Kazuo Furukawa; Eduardo D. Greaves; L. Berrin Erbay; Miloslav Hron; Yoshio Kato
1.1 The energy problem In the 21st century the stress due to environmental issues like the greenhouse effect, pollution, desertification, and local climate abnormality, as well as social issues like population explosion (100 M per year), poverty and starvation, may become intolerable, leading to large-scale disorder. However, it seems that there isn’t a more effective measure for averting such disorder and solving human poverty as ensuring an adequate supply of clean and cheap energy. In principle, it is impossible to predict the future. Nevertheless, a hypothetical prediction based on reliable principles, can be quite useful. A future energy scenario based on the initial work of Marchetti [Marchetti 1985, 1987, 1988, 1992], and later modified by the members of the Thorium Molten-Salt Forum [Furukawa, 2006; Furukawa, et al. 2008] is shown in Figures 1-4. The growth rate of primary energy in the world is estimated at 2.3% yearly (see Figure 1). In Figure 2 the historical/predicted fractional contribution F from prominent sources is shown as a function of time. In the figure the ‘‘logistic function” logarithm of F/(1 F) is plotted against the calendar year. The main sources of energy shown are wood in the past, coal, oil and natural gas at present and nuclear and solar for the future. For the solar energy two graphs are shown in view of the uncertainty in the introduction of this source for largescale deployment. For nuclear energy two scenarios are shown, one with a total nuclear energy production measured in power times years of 900 TWe year and the other with 2000 TWe year (see Figure 3). In the past 30 years the market share of usages of all main sources of energy (coal, oil, natural gas and fission) has been surprisingly constant as can be seen from Figure 2. This
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National Institute of Advanced Industrial Science and Technology
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