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Journal Articles

Study of quasielastic barrier distributions as a step towards the synthesis of superheavy elements with hot fusion reactions

Tanaka, Taiki*; Morita, Kosuke*; Morimoto, Koji*; Kaji, Daiya*; Haba, Hiromitsu*; Boll, R. A.*; Brewer, N. T.*; Van Cleve, S.*; Dean, D. J.*; Ishizawa, Satoshi*; et al.

Physical Review Letters, 124(5), p.052502_1 - 052502_6, 2020/02

 Times Cited Count:1 Percentile:30.13(Physics, Multidisciplinary)

Journal Articles

Development of a laser chipping technique combined with water jet for retrieval of fuel debris at Fukushima Daiichi Nuclear Power Station

Yamada, Tomonori; Takebe, Toshihiko*; Ishizuka, Ippei*; Daido, Hiroyuki*; Hanari, Toshihide; Shibata, Takuya; Omori, Shinya*; Kurosawa, Koichi*; Sasaki, Go*; Nakada, Masahiro*; et al.

Journal of Nuclear Science and Technology, 56(12), p.1171 - 1179, 2019/12

 Times Cited Count:0 Percentile:100(Nuclear Science & Technology)

We describe a new chipping technique combined with a water-jet technique as one of the candidate techniques for the retrieval of fuel debris and support structures as part of the decommissioning of the Fukushima Daiichi Nuclear Power Station. We performed proof-of-principle experiments to demonstrate the removal capability of metal parts, where we focused on the observation of removal processes from a metallic sample using a 5.5-kW continuous wave fiber laser combined with continuous and pulsed water jets.

Journal Articles

Nanoscale ice-type structural fluctuation in spinel titanates

Torigoe, Shuhei*; Hattori, Takayuki*; Kodama, Katsuaki; Honda, Takashi*; Sagayama, Hajime*; Ikeda, Kazutaka*; Otomo, Toshiya*; Nitani, Hiroaki*; Abe, Hitoshi*; Murakawa, Hiroshi*; et al.

Physical Review B, 98(13), p.134443_1 - 134443_7, 2018/10

Journal Articles

Demonstration of laser processing technique combined with water jet technique for retrieval of fuel debris at Fukushima Daiichi Nuclear Power Station

Hanari, Toshihide; Takebe, Toshihiko*; Yamada, Tomonori; Daido, Hiroyuki; Ishizuka, Ippei*; Omori, Shinya*; Kurosawa, Koichi*; Sasaki, Go*; Nakada, Masahiro*; Sakai, Hideaki*

Proceedings of 2017 International Congress on Advances in Nuclear Power Plants (ICAPP 2017) (CD-ROM), 3 Pages, 2017/04

In decommissioning of Fukushima Daiichi Nuclear Power Station, a retrieval process of fuel debris in the Primary Containment Vessel by a remote operation is one of the key issues. In this process, prevention of spreading radioactive materials is one of the important considerations. Furthermore, an applicable technique to the process requires keeping of reasonable processing-efficiency. We propose to use the combined technique including a laser light and a water jet as a retrieval technique of the fuel debris. The laser processing technique combined with a repetitive pulsed water jet could perform an efficient retrieval processing. Our experimental result encourages us to promote further development of the technique towards a real application at Fukushima Daiichi Nuclear Power Station.

Journal Articles

Soft phonon mode coupled with antiferromagnetic order in incipient-ferroelectric Mott insulators Sr$$_{1-x}$$Ba$$_x$$MnO$$_3$$

Sakai, Hideaki*; Fujioka, Jun*; Fukuda, Tatsuo; Bahramy, M. S.*; Okuyama, Daisuke*; Arita, Ryotaro*; Arima, Takahisa*; Baron, A. Q. R.*; Taguchi, Yasujiro*; Tokura, Yoshinori*

Physical Review B, 86(10), p.104407_1 - 104407_11, 2012/09

 Times Cited Count:23 Percentile:26.22(Materials Science, Multidisciplinary)

Journal Articles

Emergent phenomena in perovskite-type manganites

Taguchi, Yasujiro*; Sakai, Hideaki*; Okuyama, Daisuke*; Ishiwata, Shintaro*; Fujioka, Jun*; Fukuda, Tatsuo; Hashizume, Daisuke*; Kagawa, Fumitaka*; Takahashi, Yoichiro*; Shimano, Ryo*; et al.

Physica B; Condensed Matter, 407(11), p.1685 - 1688, 2012/06

 Times Cited Count:3 Percentile:82.41(Physics, Condensed Matter)

Journal Articles

Neutron scattering studies of the spin-5/2 antiferromagnetic linear trimer substance SrMn$$_3$$P$$_4$$O$$_{14}$$

Hase, Masashi*; D$"o$nni, A.*; Ozawa, Kiyoshi*; Kitazawa, Hideaki*; Sakai, Osamu*; Pomjakushin, V. Y.*; Keller, L.*; Kaneko, Koji; Metoki, Naoto; Kakurai, Kazuhisa; et al.

Journal of Physics; Conference Series, 340, p.012066_1 - 012066_7, 2012/00

 Times Cited Count:1 Percentile:51.96

We determined the magnetic structure below $$T_{rm N1}=2.2(1)$$ K of the spin-5/2 antiferromagnetic (AF) trimer substance SrMn$$_3$$P$$_4$$O$$_{14}$$ using neutron powder diffraction experiments. The incommensurate propagation vector is expressed as [0, $$k_y$$, 0], due to competition between the nearest-neighbor and next-nearest-neighbor interactions in trimerized chains. The value of $$k_y$$ is 0.316 to 0.331, changing rapidly at $$T_{rm N2}= 1.75(5)$$ K. We confirmed that the intra-trimer $$J_1$$ interaction is AF. The magnetic excitation peaks were obsereved at 0.46, 0.68, and 1.02 meV. The weak Q dependence indicates the discrete energy levels, which do not contradict the AF trimer model with the intra-trimer interaction value of 0.29 meV (3.4 K).

Journal Articles

Improvement of gas entrainment prediction method; Introduction of surface tension effect

Ito, Kei; Sakai, Takaaki; Eguchi, Yuzuru*; Monji, Hideaki*; Ohshima, Hiroyuki; Uchibori, Akihiro; Xu, Y.*

Journal of Nuclear Science and Technology, 47(9), p.771 - 778, 2010/09

 Times Cited Count:11 Percentile:33.72(Nuclear Science & Technology)

A gas entrainment (GE) prediction method has been developed to establish design criteria for the large-scale sodium-cooled fast reactor (JSFR) systems. In this paper, the evaluation accuracy of gas core lengths is improved by introducing the surface tension effects into the prototype GE prediction method. For the improvement, the mechanical balance between gravitational, centrifugal, and surface tension forces is considered. The improved GE prediction method is validated by analyzing the gas core lengths observed in simple experiments. Results show that the analytical gas core lengths calculated by the improved GE prediction method become shorter in comparison to the prototype GE prediction method, and are in good agreement with the experimental data. In addition, the experimental data under different temperature and surfactant concentration conditions are reproduced by the improved GE prediction method.

Journal Articles

Field-induced incommensurate-to-commensurate transition in the triangular lattice antiferromagnet GdPd$$_2$$Al$$_3$$

Inami, Toshiya; Terada, Noriki*; Kitazawa, Hideaki*; Sakai, Osamu*

Journal of Physics; Conference Series, 200, p.032022_1 - 032022_4, 2010/02

 Times Cited Count:0 Percentile:100

Journal Articles

Effect of experimental conditions on gas core length and downward velocity of free surface vortex in cylindrical vessel

Monji, Hideaki*; Shinozaki, Tatsuya*; Kamide, Hideki; Sakai, Takaaki

Journal of Engineering for Gas Turbines and Power, 132(1), p.012901_1 - 012901_8, 2010/01

 Times Cited Count:12 Percentile:41.25(Engineering, Mechanical)

This paper deals with characteristics of surface vortex in a cylindrical vessel. One of the characteristics is a gas core length which is important to estimate the onset condition of the gas entrainment but influenced easily by the experimental condition. In the experiment using water, the effects of the water temperature, water level and the surface tension on the gas core length were investigated. The onset condition of the gas entrainment is sometimes estimated by using the Burgers vortex model but the real flow in the vessel is different from the model. The velocity fields were measured by PIV and the velocity gradient of the downward flow was discussed. The proper flow conditions for the Burgers vortex model are a high water level and a high flow rate.

Journal Articles

Resonant magnetic X-ray diffraction study on the triangular lattice antiferromagnet GdPd$$_2$$Al$$_3$$

Inami, Toshiya; Terada, Noriki*; Kitazawa, Hideaki*; Sakai, Osamu*

Journal of the Physical Society of Japan, 78(8), p.084713_1 - 084713_5, 2009/08

 Times Cited Count:10 Percentile:42.05(Physics, Multidisciplinary)

Journal Articles

Proposal of design criteria for gas entrainment from vortex dimples based on a computational fluid dynamics method

Sakai, Takaaki; Eguchi, Yuzuru*; Monji, Hideaki*; Ito, Kei; Ohshima, Hiroyuki

Heat Transfer Engineering, 29(8), p.731 - 739, 2008/08

 Times Cited Count:28 Percentile:22.1(Thermodynamics)

Design criteria for gas entrainments (GE) from the liquid surface in a fast breeder reactor system were proposed in this paper for the two types of GE phenomena from a vortex dimple based on a computational fluid dynamics (CFD) method. The first gas entrainment phenomenon is a gas core extension directly to the outlet piping level, which induces large amount of GE to the flow system. The second is continuous bubble detachments from the tip of the vortex dimple. Based on CFD calculations for elemental experiments of the surface vortex, local CFD non-dimensional numbers were defined as the design criteria to prevent GE. In conclusion, it was found that the CFD non-dimensional numbers are useful for the design parameters of GE prevention.

JAEA Reports

Description of "Design guideline for gas entrainment prevention using CFD method" (Cooperative research)

Ohshima, Hiroyuki; Sakai, Takaaki; Kamide, Hideki; Kimura, Nobuyuki; Ezure, Toshiki; Uchibori, Akihiro; Ito, Kei; Kunugi, Tomoaki*; Okamoto, Koji*; Tanaka, Nobuatsu*; et al.

JAEA-Research 2008-049, 44 Pages, 2008/06

JAEA-Research-2008-049.pdf:42.3MB

Japan Atomic Energy Agency has conducted a conceptional design study of a sodium-cooled fast reactor in a frame work of the FBR feasibility study. The plant system concept for a commercial step is intended to minimize a vessel diameter to achieve an economical competitiveness. Therefore, the coolant in the vessel has relatively higher velocity and gas entrainment (GE) prevention from a liquid surface in the reactor vessel becomes one of important issues for the thermal-hydraulic design. In order to establish a design criteria for the GE prevention, the GE from vortex dimples at the liquid surface was investigated by a working group. The 1st proposal of "Design Guideline for Gas Entrainment Prevention Using CFD Method" was established based on the knowledge gained from the working group activities. This report introduces each study in the working group to clarify the basis of the design guideline.

Journal Articles

Effect of experimental conditions on gas core length and downward velocity of free surface vortex in cylindrical vessel

Monji, Hideaki*; Shinozaki, Tatsuya*; Kamide, Hideki; Sakai, Takaaki

Proceedings of 16th International Conference on Nuclear Engineering (ICONE-16) (CD-ROM), 9 Pages, 2008/05

This paper deals with characteristics of surface vortex in a cylindrical vessel. One of the characteristics is a gas core length which is important to estimate the onset condition of the gas entrainment but influenced easily by the experimental condition. In the experiment using water, the effects of the water temperature, water level and the surface tension on the gas core length were investigated. The onset condition of the gas entrainment is sometimes estimated by using the Burgers vortex model but the real flow in the vessel is different from the model. The velocity fields were measured by PIV and the velocity gradient of the downward flow was discussed. The proper flow conditions for the Burgers vortex model are a high water level and a high flow rate.

Journal Articles

The H-Invitational Database (H-InvDB); A Comprehensive annotation resource for human genes and transcripts

Yamasaki, Chisato*; Murakami, Katsuhiko*; Fujii, Yasuyuki*; Sato, Yoshiharu*; Harada, Erimi*; Takeda, Junichi*; Taniya, Takayuki*; Sakate, Ryuichi*; Kikugawa, Shingo*; Shimada, Makoto*; et al.

Nucleic Acids Research, 36(Database), p.D793 - D799, 2008/01

 Times Cited Count:50 Percentile:24.32(Biochemistry & Molecular Biology)

Here we report the new features and improvements in our latest release of the H-Invitational Database, a comprehensive annotation resource for human genes and transcripts. H-InvDB, originally developed as an integrated database of the human transcriptome based on extensive annotation of large sets of fulllength cDNA (FLcDNA) clones, now provides annotation for 120 558 human mRNAs extracted from the International Nucleotide Sequence Databases (INSD), in addition to 54 978 human FLcDNAs, in the latest release H-InvDB. We mapped those human transcripts onto the human genome sequences (NCBI build 36.1) and determined 34 699 human gene clusters, which could define 34 057 protein-coding and 642 non-protein-coding loci; 858 transcribed loci overlapped with predicted pseudogenes.

Journal Articles

Proposal of design criteria for gas entrainment from vortex dimples based on a computational fluid dynamics method

Sakai, Takaaki; Eguchi, Yuzuru*; Monji, Hideaki*; Iwasaki, Takashi*; Ito, Kei; Ohshima, Hiroyuki

Proceedings of 5th Korea-Japan Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-5), p.406 - 413, 2006/11

Design criteria for gas entrainments (GE) from the liquid surface in a fast breeder reactor system were proposed in this paper for the two types of GE phenomena from a vortex dimple based on a computational fluid dynamics (CFD) method. The first gas entrainment phenomenon is a gas core extension directly to the outlet piping level, which induces large amount of GE to the flow system. The second is continuous bubble detachments from the tip of the vortex dimple. Based on CFD calculations for elemental experiments of the surface vortex, local CFD non-dimensional numbers were defined as the design criteria to prevent GE. In conclusion, it was found that the CFD non-dimensional numbers are useful for the design parameters of GE prevention.

Journal Articles

Study on the gas entrainment design method by CFD data on steady cylindrical systems for a sodium-cooled reactor

Sakai, Takaaki; Monji, Hideaki*; Eguchi, Yuzuru*; Iwasaki, Takashi*; Ohshima, Hiroyuki

Proceedings of 2006 International Congress on Advances in Nuclear Power Plants (ICAPP '06) (CD-ROM), 7 Pages, 2006/06

Design method for gas entrainment (GE) from liquid surfaces in a sodium-cooled fast breeder reactor (FBR) was studied. As one of trials to develop the design method by a computation fluid dynamics (CFD) technique, prediction of the GE condition from a surface vortex dimple in a cylindrical tank was performed by using a conventional CFD method. The CFD results showed reasonable agreements with the measured velocity profiles in experiments. Non-dimensional numbers by using the CFD results were proposed for the criteria of GE prevention. The GE design map was drawn by the CFD non-dimensional numbers for the existing CFD database. It was prospective that the gas entrainment can be evaluated by using the map of CFD non-dimensional numbers.

Journal Articles

Present design and calculation for the injection-dump line of the RCS at J-PARC

Saha, P. K.; Noda, Fumiaki*; Irie, Yoshiro; Hocchi, Hideaki; Takayanagi, Tomohiro; Hayashi, Naoki; Machida, Shinji*; Sakai, Izumi*

Proceedings of 2005 Particle Accelerator Conference (PAC '05) (CD-ROM), p.3739 - 3741, 2005/00

The RCS(rapid cycling synchrotron) of J-PARC(Japan proton accelerator research complex) acts as an injector to the main ring as well as a high-power beam for the spallation neutron source at a repetition rate of 25 Hz, where at present the injection and the extraction beam energy are chosen to be 0.181 GeV and 3.0 GeV, respectively. The present work concerns on the present design and calculations for the injection-dump line of the RCS, which includes, (1) an accurate aperture list of all elements taking into account a wide range of the betatron tune, effect of changing injection modes, multiple trajectories of different particles after the charge-exchange foil(like H0 from the H- and H- beam itself)and (2) an accurate estimation of the uncontrolled beam losses especially from the H0-excited states, multiple coulomb scattering at the charge-exchange foil and also the lorentz stripping loss at the septum magnets so as to optimize them concerning mainly the radiation issues as well as for the hands-on maintenance.

JAEA Reports

Stress, Hydraulic and Coupled Stress-Hydraulic Analysis at Experimental Region in the Tunnel Sealing Experiment

Sugita, Yutaka; Suzuki, Hideaki*; Ito, Akira; Sakai, Yuichi*; Kawakami, Susumu

JNC-TN8400 2003-045, 61 Pages, 2004/02

JNC-TN8400-2003-045.pdf:3.28MB

Japan Nuclear Cycle Development Institute has joined the international project, the Tunnel Sealing Experiment, to demonstrate the sealing performance of the full scale plugs in-situ, and to develop analytical method of the sealing performance of the plugs at the Underground Research Laboratory of Atomic Energy of Canada Limited in Canada. We performed the analysis of the sealing performance of the full scale plugs considering the monitored data on sealing performance of the plugs. In these analyses, stress analysis, hydraulic analysis and coupled stress-hydraulic analysis were performed to explain distribution of the pore pressure in host rock and seepage through plugs.Stress analysis showed the stress condition in host around the test tunnel. Hydraulic and coupled stress-hydraulic analyses showed the change with time of pore pressure and seepages considering schedules of opening of the test tunnel, installation of the plugs and pressurizing of the chamber. Since opening the test tunnel caused changes of the pore pressure in host rock around the test tunnel, the coupled stress-hydraulic analysis explained distribution of the pore pressure in the host rock around the test tunnel and seepage through plugs.

Journal Articles

Deterministic approach towards establishing of clearance levels in Japan

Okoshi, Minoru; Sakai, Akihiro; Yoshimori, Michiro; Yamamoto, Hideaki; Takahashi, Tomoyuki; Kimura, Hideo

Proc. of 7th Int. Conf. on Radioactive Waste Management and Environmental Remediation (ICEM'99)(CD-ROM), 8 Pages, 1999/09

no abstracts in English

29 (Records 1-20 displayed on this page)