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Journal Articles

Properties of minor actinide compounds relevant to nuclear fuel technology

Minato, Kazuo; Takano, Masahide; Nishi, Tsuyoshi; Ito, Akinori; Akabori, Mitsuo

Recent Advances in Actinide Science, p.317 - 322, 2006/06

To reduce the radiotoxicity of the high-level waste and to use the repository efficiently, recycling of minor actinides (MA: Np, Am, Cm) as well as plutonium is an option for the future nuclear fuel cycle. For MA-bearing fuel development, new facilities with inert atmosphere were installed and the thermal properties of minor actinide compounds, especially nitrides and oxides, were measured. Minor actinide nitrides were prepared by carbothermic reduction of the oxides. Lattice parameter and its thermal expansion were measured by high-temperature X-ray diffraction, and thermal diffusivity by laser flash method.

Journal Articles

Effect of implanted helium on thermal diffusivities of SiC/SiC composites

Taguchi, Tomitsugu; Igawa, Naoki; Jitsukawa, Shiro; Shimura, Kenichiro

Nuclear Instruments and Methods in Physics Research B, 242(1-2), p.469 - 472, 2006/01

 Times Cited Count:2 Percentile:77.71(Instruments & Instrumentation)

SiC/SiC composites are one of the candidate materials for first wall in a fusion reactor because of their high strength at high temperature and low residual radioactivity after irradiation. In the fusion reactor, these materials are required to have high thermal diffusivity for heat exchange and reducing the thermal shock. Under fusion conditions, helium (He) and hydrogen (H) are produced in SiC. In this study, the effect of He ions implantation on the thermal diffusivities of SiC and SiC/SiC composite were investigated. In the results, the thermal diffusivities of SiC and SiC/SiC composites decreased after He ions implantation. However, the thermal diffusivities of SiC and SiC/SiC composites hardly reduced in the operation temperature of fusion reactor. The thermal diffusivities of He implanted specimens were partly recovered by annealing. The defect concentration induced by He implantation, X$$_{irradiation}$$, in SiC/SiC composites was estimated. The X$$_{irradiation}$$ rapidly decreased around 500 $$^{circ}$$C. The reason is that the He release from SiC starts at 500 $$^{circ}$$C.

JAEA Reports

Development and installation of thermal diffusivity measurement apparatus for minor actinide compounds (Contract research)

Nishi, Tsuyoshi; Takano, Masahide; Ito, Akinori; Akabori, Mitsuo; Minato, Kazuo; Kizaki, Minoru

JAERI-Tech 2005-051, 13 Pages, 2005/09

JAERI-Tech-2005-051.pdf:1.38MB

An apparatus has been developed to measure the thermal diffusivities of minor actinide (MA) compounds. By installing the laser flash apparatus in a glove box with highly purified inert gas atmosphere, the thermal diffusivities measurement of MA compounds of $$alpha$$-decay nuclides was enabled. A new sample holder has been also developed to measure the thermal diffusivities of very small samples. The performance of this new apparatus was confirmed by measuring the thermal diffusivities of small samples of tantalum, nickel and cerium oxides. The thermal diffusivity values obtained in this work agreed well with the literature values and the values measured by a conventional thermal diffusivities measurement apparatus. Accordingly, this apparatus was found to be useful for thermal diffusivities measurement of MA compounds.

Journal Articles

Thermal diffusivity/conductivity of Tyranno SA fiber- and Hi-Nicalon type S fiber-reinforced 3-D SiC/SiC composites

Yamada, Reiji; Igawa, Naoki; Taguchi, Tomitsugu

Journal of Nuclear Materials, 329-333(Part1), p.497 - 501, 2004/08

 Times Cited Count:22 Percentile:18.46(Materials Science, Multidisciplinary)

SiC fiber reinforced SiC composites (SiC/SiC) have a potential for a structural material for a blanket wall of advanced fusion reactors. To reduce thermal stresses in the wall under heavy thermal loads SiC/SiC composites are expected to have high thermal conductivity as possible. Advanced SiC fibers recently developed, such as Tyranno SA and Hi-Nicalon Type S have been employed for weaving 3D textures as well as those 2D unwoven fabrics. The CVI and PIP/CVI fabrication methods were used. The thermal conductivity at RT was 40-50 W/mK and 35-40 W/mK for Tyranno CVI and PIP/CVI composites, respectively, whereas about 25 and about 17 W/mK at 1000 $$^{circ}$$C. 2D unwoven CVI composites had less than 12 W/mK for RT-1000 $$^{circ}$$C. For Hi-Nicalon Type S, 3D CVI composites had about 35 and about 20 for RT and 1000 $$^{circ}$$C, respectively. The reason of these high thermal conductivities was ascribed to higher density as well as better SiC crystallinity. The fiber configuration effects on the thermal conductivity of SiC/SiC composites were dominant in the low temperature region.

Journal Articles

Effect of air-oxidation on the thermal diffusivity of the nuclear grade 2-dimensional carbon fiber reinforced carbon/carbon composite

Sogabe, Toshiaki; Ishihara, Masahiro; Baba, Shinichi; Tachibana, Yukio; Yamaji, Masatoshi*; Iyoku, Tatsuo; Hoshiya, Taiji*

Materials Science Research International, 9(3), p.235 - 241, 2003/09

2D-C/C composite is one of the promising materials as a next-generation core material in gas-cooled reactors. Effect of air-oxidation on the thermal diffusivity up to 1673K of the 2D-C/C composite was investigated. The C/C composite specimens for measurement of thermal diffusivity were oxidized from 1 to 11 percent weight loss in air at 823K. Thermal diffusivity at room temperature declined 10$$sim$$20 percent for parallel to lamina direction and 5$$sim$$9 percent for that of perpendicular within 11 percent weight loss by oxidation. Thermal diffusivity tended to decrease gradually as the increase of oxidation loss in parallel to lamina, however, it decreased in the beginning of oxidation pretty much and not so changed by further oxidation loss in perpendicular to lamina. Change in thermal conductivity under oxidation condition was also estimated.

Journal Articles

Effect of superplastic deformation on thermal diffusivity of 3Y-TZP

Wan, C.*; Motohashi, Yoshinobu*; Shibata, Taiju; Baba, Shinichi; Ishihara, Masahiro; Hoshiya, Taiji

Journal of Iron and Steel Research, International, Special Issue IFAMST, p.85 - 89, 2002/06

no abstracts in English

Journal Articles

Thermal conductivities of irradiated UO$$_{2}$$ and (U,Gd)O$$_{2}$$

Minato, Kazuo; Shiratori, Tetsuo; Serizawa, Hiroyuki; Hayashi, Kimio; Une, Katsumi*; Nogita, Kazuhiro*; Hirai, Mutsumi*; Amaya, M.*

Journal of Nuclear Materials, 288(1), p.57 - 65, 2001/01

 Times Cited Count:19 Percentile:20.1(Materials Science, Multidisciplinary)

no abstracts in English

JAEA Reports

Comparison of heat capacity and thermal time constant between BWR fuel and simulated heater rod

Iguchi, Tadashi

JAERI-Research 2000-050, 107 Pages, 2000/09

JAERI-Research-2000-050.pdf:4.29MB

no abstracts in English

Journal Articles

JAERI's recent activities on SiC/SiC composites for fusion

Yamada, Reiji; Taguchi, Tomitsugu; Igawa, Naoki; Jitsukawa, Shiro

Proceedings of 4th International Energy Agency Workshop on SiCf/SiC Ceramic Composites for Fusion Structural Application, p.33 - 41, 2000/00

no abstracts in English

Journal Articles

Characterization of technetium-ruthenium alloys for transmutation of technetium metal

Shirasu, Yoshiro; Minato, Kazuo

Proc. of the Int. Conf. on Future Nuclear Systems (GLOBAL'99)(CD-ROM), 7 Pages, 1999/00

no abstracts in English

Journal Articles

Properties of technetium and technetium-ruthenium alloys for transmutation of technetium

Minato, Kazuo; Shirasu, Yoshiro

Proceedings of 2nd Japanese-Russian Seminar on Technetium, p.77 - 78, 1999/00

no abstracts in English

Journal Articles

Thermal expansion and thermal conductivity of cesium uranates

Takano, Masahide; Minato, Kazuo; Fukuda, Kosaku; Sato, Seichi*; Ohashi, Hiroshi*

Journal of Nuclear Science and Technology, 35(7), p.485 - 493, 1998/07

 Times Cited Count:4 Percentile:59.98(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Thermal conductivity of technetium

Minato, Kazuo; Serizawa, Hiroyuki; Fukuda, Kosaku

Journal of Alloys and Compounds, 267, p.274 - 278, 1998/00

 Times Cited Count:6 Percentile:52.09

no abstracts in English

Journal Articles

Study of internal transport barriers by comparison of reversed shear and high-$$beta$$$$_{p}$$ discharges in JT-60U

Koide, Yoshihiko; Mori, Masahiro; Fujita, Takaaki; Shirai, Hiroshi; Hatae, Takaki; Takizuka, Tomonori; Kimura, Haruyuki; Oikawa, Toshihiro; Isei, Nobuaki; Isayama, Akihiko; et al.

Plasma Physics and Controlled Fusion, 40(5), p.641 - 645, 1998/00

 Times Cited Count:25 Percentile:36.28(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Preparation and characterisation of technetium metal and technetium-ruthenium alloys

Minato, Kazuo; Shirasu, Yoshiro

Proc. of 5th Int. Information Exchange Meeting on Actinide and Fission Product Partitioning, p.223 - 230, 1998/00

no abstracts in English

JAEA Reports

Sample preparation and characterization of technetium metal

Minato, Kazuo; Serizawa, Hiroyuki; Fukuda, Kosaku; Ito, Mitsuo

JAERI-Research 97-077, 17 Pages, 1997/10

JAERI-Research-97-077.pdf:1.09MB

no abstracts in English

Journal Articles

Thermal expansion and thermal conductivity of cesium molybdate

Minato, Kazuo; Takano, Masahide; Fukuda, Kosaku; Sato, Seichi*; Ohashi, Hiroshi*

Journal of Alloys and Compounds, 255, p.18 - 23, 1997/00

 Times Cited Count:12 Percentile:35.2(Chemistry, Physical)

no abstracts in English

Journal Articles

Thermal properties of cesium molybdate

Minato, Kazuo; Takano, Masahide*; Sato, Seichi*; Ohashi, Hiroshi*; Fukuda, Kosaku

Transactions of the American Nuclear Society, 74, p.95 - 96, 1996/00

no abstracts in English

Journal Articles

Post-irradiation examination of high burnup HBWR fuel rods at JAERI

Nakamura, Jinichi; Uetsuka, Hiroshi; Kono, Nobuaki; ; ; Furuta, Teruo

HPR-345 (Vol. II), 0, 13 Pages, 1995/00

no abstracts in English

Journal Articles

Companion sample examination and related study at JAERI

Uetsuka, Hiroshi; Nagase, Fumihisa

Proceedings of Three Mile Island Reactor Pressure Vessel Investigation Project Open Forum, p.269 - 280, 1994/00

no abstracts in English

39 (Records 1-20 displayed on this page)