Refine your search:     
Report No.
 - 
Search Results: Records 1-20 displayed on this page of 77

Presentation/Publication Type

Initialising ...

Refine

Journal/Book Title

Initialising ...

Meeting title

Initialising ...

First Author

Initialising ...

Keyword

Initialising ...

Language

Initialising ...

Publication Year

Initialising ...

Held year of conference

Initialising ...

Save select records

Journal Articles

Thermophysical properties of dense molten Al$$_{2}$$O$$_{3}$$ determined by aerodynamic levitation

Sun, Y.*; Takatani, Tomoya*; Muta, Hiroaki*; Fujieda, Shun*; Kondo, Toshiki; Kikuchi, Shin; Kargl, F.*; Oishi, Yuji*

International Journal of Thermophysics, 45(1), p.11_1 - 11_19, 2024/01

no abstracts in English

Journal Articles

Thermophysical properties of molten (Fe$$_{2}$$O$$_{3}$$)$$_{0.95}$$-(SiO$$_{2}$$)$$_{0.05}$$ measured by aerodynamic levitation

Kondo, Toshiki; Toda, Taro*; Takeuchi, Junichi*; Kikuchi, Shin; Kargl, F.*; Muta, Hiroaki*; Oishi, Yuji*

High Temperatures-High Pressures, 52(3-4), p.307 - 321, 2023/06

 Times Cited Count:0 Percentile:0.02(Thermodynamics)

In order to establish an evaluation method/numerical simulation for nuclear reactor safety under severe accidental conditions, it is necessary to obtain the physical properties, especially fluidity of the relevant molten materials at very high temperatures. In this study, thermophysical properties such as density and viscosity were obtained for (Fe$$_{2}$$O$$_{3}$$)$$_{0.95}$$-(SiO$$_{2}$$)$$_{0.05}$$, which is a representative composition in the early stage of severe accident. (Fe$$_{2}$$O$$_{3}$$)$$_{0.95}$$-(SiO$$_{2}$$)$$_{0.05}$$ is produced by the contact between the molten oxide of steel, which is the main component of the reactor, and SiO$$_{2}$$, which is the main component of concrete. As a result, the physical properties of the (Fe$$_{2}$$O$$_{3}$$)$$_{0.95}$$-(SiO$$_{2}$$)$$_{0.05}$$ mixture were almost the same as those of Fe$$_{2}$$O$$_{3}$$ obtained in previous studies, and it could be concluded that a small amount of SiO$$_{2}$$ (about 5 mol.%) did not significantly affect the fluidity of Fe$$_{2}$$O$$_{3}$$.

Journal Articles

Thermophysical properties of molten FeO$$_{1.5}$$, (FeO$$_{1.5}$$)$$_{0.86}$$-(ZrO$$_{2}$$)$$_{0.14}$$ and (FeO$$_{1.5}$$)$$_{0.86}$$-(UO$$_{2}$$)$$_{0.14}$$

Kondo, Toshiki; Toda, Taro*; Takeuchi, Junichi*; Kargl, F.*; Kikuchi, Shin; Muta, Hiroaki*; Oishi, Yuji*

Journal of Nuclear Science and Technology, 59(9), p.1139 - 1148, 2022/09

 Times Cited Count:1 Percentile:33.72(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Visualization of the boron distribution in core material melting and relocation specimen by neutron energy resolving method

Abe, Yuta; Tsuchikawa, Yusuke; Kai, Tetsuya; Matsumoto, Yoshihiro*; Parker, J. D.*; Shinohara, Takenao; Oishi, Yuji*; Kamiyama, Takashi*; Nagae, Yuji; Sato, Ikken

JPS Conference Proceedings (Internet), 33, p.011075_1 - 011075_6, 2021/03

Journal Articles

Feasibility study of PGAA for boride identification in simulated melted core materials

Tsuchikawa, Yusuke; Abe, Yuta; Oishi, Yuji*; Kai, Tetsuya; Toh, Yosuke; Segawa, Mariko; Maeda, Makoto; Kimura, Atsushi; Nakamura, Shoji; Harada, Masahide; et al.

JPS Conference Proceedings (Internet), 33, p.011074_1 - 011074_6, 2021/03

In the decommissioning of the Fukushima-Daiichi (1F) Nuclear Power Plant, it is essential to understand characteristics of the melted core materials. The estimation of boride in the real debris is of great importance to develop safe debris removal plans. Hence, it is required to investigate the amount of boron in the melted core materials with nondestructive methods. Prompt gamma-ray activation analysis (PGAA) is one of the useful techniques to determine the amount of borides by means of the 478 keV prompt gamma-ray from neutron absorption reaction of boron. Moreover, it is well known that the width of the 478 keV gamma-ray peak is typically broadened due to the Doppler effect. The degree of the broadening is affected by coexisting materials, and can be recognized by the width of the prompt gamma-ray peak. As a feasibility study, the prompt gamma-ray from boride samples were measured using the ANNRI, NOBORU, and RADEN beamlines at the Materials and Life Science Experimental Facility (MLF) of Japan Proton Accelerator Complex (J-PARC).

Journal Articles

Measurement of Doppler broadening of prompt gamma-rays from various zirconium- and ferro-borons

Tsuchikawa, Yusuke; Kai, Tetsuya; Abe, Yuta; Oishi, Yuji*; Sun, Y.*; Oikawa, Kenichi; Nakatani, Takeshi; Sato, Ikken

Nuclear Instruments and Methods in Physics Research A, 991, p.164964_1 - 164964_5, 2021/03

 Times Cited Count:0 Percentile:19.67(Instruments & Instrumentation)

Peak shape analysis was performed for the energy spectra of Doppler-broadened prompt $$gamma$$-rays generated by neutron capture reactions with various boride or boron samples. Significant differences were observed between nonmetallic and metallic borides. Minor differences between the peak shapes of prompt $$gamma$$-rays from zirconium- and ferro-borons were evaluated by a peak fitting method. The identification of zirconium- and ferro-borons and other types of borides was estimated.

Journal Articles

Mechanical and thermal properties of Zr-B and Fe-B alloys

Sun, Y.*; Abe, Yuta; Muta, Hiroaki*; Oishi, Yuji*

Journal of Nuclear Science and Technology, 57(8), p.917 - 925, 2020/08

 Times Cited Count:4 Percentile:54.54(Nuclear Science & Technology)

Journal Articles

Development of three-dimensional distribution visualization technology for boron using energy resolved neutron-imaging system (RADEN)

Abe, Yuta; Tsuchikawa, Yusuke; Kai, Tetsuya; Matsumoto, Yoshihiro*; Parker, J. D.*; Shinohara, Takenao; Oishi, Yuji*; Kamiyama, Takashi*; Nagae, Yuji; Sato, Ikken

Proceedings of 2020 International Conference on Nuclear Engineering (ICONE 2020) (Internet), 6 Pages, 2020/08

Journal Articles

Low temperature heat capacity of Cs$$_{2}$$Si$$_{4}$$O$$_{9}$$

Suzuki, Eriko; Nakajima, Kunihisa; Osaka, Masahiko; Oishi, Yuji*; Muta, Hiroaki*; Kurosaki, Ken*

Journal of Nuclear Science and Technology, 57(7), p.852 - 857, 2020/07

 Times Cited Count:3 Percentile:46.37(Nuclear Science & Technology)

The low temperature heat capacity of Cs$$_{2}$$Si$$_{4}$$O$$_{9}$$, which is one of the cesium chemisorbed compounds onto stainless steel during severe accident of the light water nuclear reactor, was experimentally determined for the first time in the temperature range of 1.9 - 302 K. The experimentally determined heat capacity, $$C_{p}$$$$^{o}$$ (298.15K), and the standard entropy, $$S^{o}$$ (298.15K), were 249.4 $$pm$$ 1.1 J K$$^{-1}$$ mol$$^{-1}$$ and 322.1 $$pm$$ 1.3 J K$$^{-1}$$ mol$$^{-1}$$, respectively. The standard Gibbs energy of formation of Cs$$_{2}$$Si$$_{4}$$O$$_{9}$$ at high temperatures, $$Delta$$$$_{f}$$$$G^{o}$$($$T$$), were reevaluated by using the presently obtained $$S^{o}$$ (298.15K) and the previously reported experimental results of the standard enthalpy of formation, $$Delta$$$$_{f}$$$$H^{o}$$ (298.15K), and the standard enthalpy increments at high temperatures, $$H^{o}$$($$T$$)-$$H^{o}$$ (298.15K).

Journal Articles

Chemical trapping of Sr vapor species by Zircaloy cladding under a specific chemical condition

Mohamad, A.*; Nakajima, Kunihisa; Suzuki, Eriko; Miwa, Shuhei; Osaka, Masahiko; Oishi, Yuji*; Muta, Hiroaki*; Kurosaki, Ken*

Proceedings of International Topical Workshop on Fukushima Decommissioning Research (FDR 2019) (Internet), 4 Pages, 2019/05

In the accident of Fukushima Daiichi Nuclear Power Station, formation of a volatile SrCl$$_{2}$$ could have occurred by the sea-water injection into the core. This can cause the release of non-volatile group Sr from the fuel to induce chemical reactions with reactor structural materials, such as stainless steel and Zircaloy (Zry) cladding. Such reactions could cause the changes in distribution of Sr in the reactor. Chemical reactions between Sr species and Zry were therefore investigated experimentally. As the result, it can be said that Sr vapor species were chemically trapped right after the release from fuel. This trapping effect of Sr by Zry-cladding implies a possibility of preferable Sr retention in the oxide phase of debris.

Journal Articles

Synthesis and characterization of CeO$$_{2}$$-based simulated fuel containing CsI

Takamatsu, Yuki*; Ishii, Hiroto*; Oishi, Yuji*; Muta, Hiroaki*; Yamanaka, Shinsuke*; Suzuki, Eriko; Nakajima, Kunihisa; Miwa, Shuhei; Osaka, Masahiko; Kurosaki, Ken*

Nihon Genshiryoku Gakkai Wabun Rombunshi, 17(3/4), p.106 - 110, 2018/12

In order to establish the synthesis method of simulated fuel contacting Cesium (Cs) which is required for the evaluation of physical/chemical characteristics in fuel and release behavior of Cs, sintering tests of the cerium dioxide (CeO$$_{2}$$) based simulated fuels containing Cesium iodide (CsI) are performed by using spark plasma sintering (SPS) method. The sintered CeO$$_{2}$$ pellets with homogeneous distribution of several micro meter of CsI spherical precipitates were successfully obtained by optimizing SPS conditions.

Journal Articles

Effect of hydrogenation conditions on the microstructure and mechanical properties of zirconium hydride

Muta, Hiroaki*; Nishikane, Ryoji*; Ando, Yusuke*; Matsunaga, Junji*; Sakamoto, Kan*; Harjo, S.; Kawasaki, Takuro; Oishi, Yuji*; Kurosaki, Ken*; Yamanaka, Shinsuke*

Journal of Nuclear Materials, 500, p.145 - 152, 2018/03

 Times Cited Count:11 Percentile:77.59(Materials Science, Multidisciplinary)

Journal Articles

Formation and morphology of UO$$_{2}$$ image crystal

Serizawa, Hiroyuki; Oishi, Yuji*; Kaji, Yoshiyuki; Yamanaka, Shinsuke*

New Research Trends of Fluorite-Based Oxide Materials, p.243 - 262, 2015/01

The image crystal is a shape controllable negative crystal which is sometimes reported by mineralogist. The negative crystals formed in a large single-crystal mass have attracted interest as expensive jewelry because of their mysterious appearance and rarity. Nonetheless, for many scientist, the cavity has been nothing else than a volume defect which occurs in a single crystal by chance. However, the authors found unexpectedly that the image crystal is formed in UO$$_{2}$$ when helium is enclosed in the gas bubble. They also found that the shape of the image crystal changes dramatically with the conditions of helium precipitation, which implies that the shape of the cavity should change depending on the inner pressure. A truncated octahedron-type, an octa-triacontahedron-type and a pentacontahedron-type negative crystal were observed. Recent study clarified that the growth process of the image crystal can be explained by a step free energy model rather than an attachment energy.

Journal Articles

Thermophysical properties of BaUO$$_{4}$$

Tanaka, Kosuke; Tokushima, Kazuyuki*; Kurosaki, Ken*; Oishi, Yuji*; Muta, Hiroaki*; Yamanaka, Shinsuke*

Journal of Nuclear Materials, 443(1-3), p.218 - 221, 2013/11

 Times Cited Count:0 Percentile:0.01(Materials Science, Multidisciplinary)

Polycrystalline specimens of barium uranate, BaUO$$_{4}$$, were prepared and several properties such as the thermal expansion coefficient, elastic moduli, thermal conductivity, and Debye temperature were evaluated.

Journal Articles

Formation and growth of image crystals by helium precipitation

Serizawa, Hiroyuki; Matsunaga, Junji*; Haga, Yoshinori; Nakajima, Kunihisa; Akabori, Mitsuo; Tsuru, Tomohito; Kaji, Yoshiyuki; Kashibe, Shinji*; Oishi, Yuji*; Yamanaka, Shinsuke*

Crystal Growth & Design, 13(7), p.2815 - 2823, 2013/07

 Times Cited Count:5 Percentile:42.85(Chemistry, Multidisciplinary)

Since the shape of the negative crystal closely relates to the morphology of the crystal habits, the formation and the growth mechanism is important subject in a field of the physical science. Whereas, the negative crystal formed in a large single crystal mass has been arousing interest as an expensive jewelry because of its mysterious appearance and rarity. However, it is difficult to control the shape of this polyhedral cavity embedded in a solid medium arbitrary. Here we report the recent discovery on the growth process of the negative crystal. We found that precipitated helium forms the negative crystal in UO$$_{2}$$; the shape changes drastically with the condition of the helium precipitation. The transformation mechanism was discussed in this article. Our investigation implies that the shape of the negative crystal can be arbitrary controlled by controlling the precipitation condition.

Journal Articles

Actinide-handling experience for training and education of future expert under J-ACTINET

Osaka, Masahiko; Konashi, Kenji*; Hayashi, Hirokazu; Li, D.*; Homma, Yoshiya*; Yamamura, Tomoo*; Sato, Isamu; Miwa, Shuhei; Sekimoto, Shun*; Kubota, Takumi*; et al.

Proceedings of International Conference on Toward and Over the Fukushima Daiichi Accident (GLOBAL 2011) (CD-ROM), 5 Pages, 2011/12

Summer schools for future experts have successfully been completed under Japan Actinide Network (J-ACTINET) for the purpose of development of human resources who are expected to be engaged in every areas of actinide-research/engineering. The first summer school was held in Ibaraki-area in August 2009, followed by the second one in Kansai-area in August 2010. Two summer schools have focused on actual experiences of actinides in actinide-research fields for university students and young researchers/engineers as an introductory course of actinide-researches. Several quasi actinide-handling experiences at the actinide-research fields have attracted attentions of participants at the first school in Ibaraki-area. The actual experiments using actinides-containing solutions have been carried out at the second school in Kansai-area. Future summer schools will be held every year for the sustainable human resource development in various actinide-research fields.

Journal Articles

Chemical states of fission products and actinides in irradiated oxide fuels analyzed by thermodynamic calculation and post-irradiation examination

Kurosaki, Ken*; Tanaka, Kosuke; Osaka, Masahiko; Oishi, Yuji*; Muta, Hiroaki*; Uno, Masayoshi*; Yamanaka, Shinsuke*

Proceedings of Joint International Conference of 7th Supercomputing in Nuclear Application and 3rd Monte Carlo (SNA + MC 2010) (USB Flash Drive), 4 Pages, 2010/10

It is important to understand the behavior of fission products and actinides under irradiation. In the present study, the chemical states of fission products and actinides in irradiated oxide fuels were evaluated by both thermodynamic equilibrium calculation and post-irradiation examination.

Oral presentation

Development of high-level liquid waste conditioning technology for advanced nuclear fuel cycle, 5; Characterization of Mo-Ru-Rh-Pd alloys

Kurosaki, Ken*; Oishi, Yuji*; Muta, Hiroaki*; Yamanaka, Shinsuke*; Morita, Yasuji

no journal, , 

Characterization and calcination behavior of Mo-Ru-Rh-Pd alloys was studied for the purpose of the development of solidification method for dissolution residue which appears in the dissolution of spent fuel.

Oral presentation

Thermophysical properties of complex uranium or plutonium oxides with alkaline-earth metals

Tanaka, Kosuke; Sato, Isamu; Hirosawa, Takashi; Seki, Takayuki*; Kashimura, Naoki*; Kurosaki, Ken*; Tokushima, Kazuyuki*; Muta, Hiroaki*; Oishi, Yuji*; Yamanaka, Shinsuke*

no journal, , 

Complex uranium or plutonium oxides with alkaline-earth metals were prepared by using conventional powder metallurgy and its thermophysical properties were evaluated.

Oral presentation

Development of high-level liquid waste conditioning technology for advanced nuclear fuel cycle, 8; Preparation of the composite materials of Mo-Ru-Rh-Pd alloys and oxide ceramics and characterization of their microstructure and phase state

Kurosaki, Ken*; Sugawara, Toru*; Yusuf, A.*; Oishi, Yuji*; Muta, Hiroaki*; Yamanaka, Shinsuke*; Morita, Yasuji

no journal, , 

As solidification method for insoluble residue appeared in spent nuclear fuel dissolution, the composite materials of Mo-Ru-Rh-Pd alloys and oxide ceramics were prepared by spark plasma sintering method and the characterization of the solidified materials was performed by examining their microstructure and phase state. Aluminum oxide, $$alpha$$-Al$$_{2}$$O$$_{3}$$, was used as oxide ceramics. Mixed phases of $$alpha$$-Al$$_{2}$$O$$_{3}$$ and Mo-Ru-Rh-Pd alloys were observed in the solidified materials.

77 (Records 1-20 displayed on this page)