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Kubo, Kotaro; Tanaka, Yoichi*; Ishikawa, Jun
Proceedings of the Institution of Mechanical Engineers, Part O; Journal of Risk and Reliability, 11 Pages, 2023/00
Times Cited Count：1 Percentile：0.01(Engineering, Multidisciplinary)Nanjo, Kotaro; Ishikawa, Jun; Sugiyama, Tomoyuki; Pellegrini, M.*; Okamoto, Koji*
Journal of Nuclear Science and Technology, 59(11), p.1407 - 1416, 2022/11
Times Cited Count：7 Percentile：90.45(Nuclear Science & Technology)Ohshima, Hiroyuki; Morishita, Masaki*; Aizawa, Kosuke; Ando, Masanori; Ashida, Takashi; Chikazawa, Yoshitaka; Doda, Norihiro; Enuma, Yasuhiro; Ezure, Toshiki; Fukano, Yoshitaka; et al.
Sodium-cooled Fast Reactors; JSME Series in Thermal and Nuclear Power Generation, Vol.3, 631 Pages, 2022/07
This book is a collection of the past experience of design, construction, and operation of two reactors, the latest knowledge and technology for SFR designs, and the future prospects of SFR development in Japan. It is intended to provide the perspective and the relevant knowledge to enable readers to become more familiar with SFR technology.
Kubo, Kotaro; Zheng, X.; Ishikawa, Jun; Sugiyama, Tomoyuki; Jang, S.*; Takata, Takashi*; Yamaguchi, Akira*
Proceedings of Asian Symposium on Risk Assessment and Management 2020 (ASRAM 2020) (Internet), 11 Pages, 2020/11
Dynamic probabilistic risk assessment (PRA) enables a more realistic and detailed analysis than classical PRA. However, the trade-off for these improvements is the enormous computational cost associated with performing a large number of thermal-hydraulic (TH) analyses. In this study, based on machine learning (ML), we aim to reduce these costs by skipping the TH analysis. For the ML algorithm, we selected a support vector machine; we built it using a high-fidelity/high-cost detailed model and low-fidelity/low-cost simplified model. As a result, the computational costs could be reduced by approximately 80% without significantly decreasing the accuracy under the assumed conditions.
scattering length from 
photoproduction on the proton near the reaction thresholdIshikawa, Takatsugu*; Fujimura, Hisako*; Fukasawa, Hiroshi*; Hashimoto, Ryo*; He, Q.*; Honda, Yuki*; Hosaka, Atsushi; Iwata, Takahiro*; Kaida, Shun*; Kasagi, Jirota*; et al.
Physical Review C, 101(5), p.052201_1 - 052201_6, 2020/05
Times Cited Count：4 Percentile：44.35(Physics, Nuclear)Sueyoshi, Tetsuro*; Kotaki, Tetsuya*; Furuki, Yuichi*; Fujiyoshi, Takanori*; Semboshi, Satoshi*; Ozaki, Toshinori*; Sakane, Hitoshi*; Kudo, Masaki*; Yasuda, Kazuhiro*; Ishikawa, Norito
Japanese Journal of Applied Physics, 59(2), p.023001_1 - 023001_7, 2020/02
Times Cited Count：6 Percentile：38.16(Physics, Applied)We show that Xe ion irradiation with 80 MeV to GdBa
Cu
Oy-coated conductors creates different morphologies of columnar defects (CDs) depending on the irradiation angles relative to the c-axis: continuous CDs with a larger diameter are formed for oblique irradiation at 
= 45
, whereas the same ion beam at a different angle ( = 0) induces the formation of discontinuous CDs. The direction-dependent morphologies of CDs significantly affect the angular behavior of the critical current density 
.
Sueyoshi, Tetsuro*; Kotaki, Tetsuya*; Uraguchi, Yusei*; Suenaga, Momotaro*; Makihara, Takahiro*; Fujiyoshi, Takanori*; Ishikawa, Norito
Physica C, 530, p.72 - 75, 2016/11
Times Cited Count：9 Percentile：41.05(Physics, Applied)In order to clarify the influence of size and spatial distribution of three-dimensional pinning centers (3D-PCs) on hybrid flux pinning, columnar defects (CDs) were installed by using 200 MeV Xe ions along the 
-axis direction into quasi-multilayered films consisting of YBaCuOy layers and pseudo layers of BaSnO. The positive effect of the BaSnO doping on the hybrid flux pinning stands out for the critical current density around 
in high magnetic field and/or inclined magnetic field off the -axis, whereas there is little difference in the at among the same growth temperature samples for low magnetic field. In the case of the in-plane distributed BaSnO nano-dots, the Jc around 
is remarkably enhanced, whereas there is a detrimental effect on the Jc around . These imply that the tuning of 3D-PCs is one of the keys to improve the at all magnetic field orientations for the hybrid flux pinning.
Sueyoshi, Tetsuro*; Kotaki, Tetsuya*; Furuki, Yuichi*; Uraguchi, Yusei*; Kai, Takashi*; Fujiyoshi, Takanori*; Shimada, Yusuke*; Yasuda, Kazuhiro*; Ishikawa, Norito
IEEE Transactions on Applied Superconductivity, 25(3), p.6603004_1 - 6603004_4, 2015/06
Times Cited Count：11 Percentile：50.43(Engineering, Electrical & Electronic)To investigate the effect of discontinuity of 1-D pinning centers on the flux pinning in a wide range of magnetic field directions, discontinuous columnar defects (CDs) and continuous CDs were formed in GdBCO coated conductors using Xe-ion irradiations with 80 and 270 MeV, respectively. An overall shift upward in Jc, for the 80-MeV-irradiated sample compared to the 270-MeV-irradiated one, can be observed in every direction of magnetic field, which is more remarkable as temperature decreases. This implies a synergetic effect of the pinning interaction between the linearity and the discontinuity for the discontinuous CDs.
-values in BaZrO/YBaCuO
quasi-multilayered films with columnar defectsSueyoshi, Tetsuro*; Kotaki, Tetsuya*; Fujiyoshi, Takanori*; Mitsugi, Fumiaki*; Ikegami, Tomoaki*; Ishikawa, Norito
Physica C, 494, p.153 - 157, 2013/11
Times Cited Count：5 Percentile：25.14(Physics, Applied)BaZrO/YBaCuOy quasi-multilayered films, in which the size and the spatial distribution of BaZrO nano-particles were controlled, were irradiated using 200 MeV Xe ions along the c-axis direction. Whenthe BaZrO nano-particles were larger in size, the flux lines not captured by CDs, such as interstitial fluxlines between CDs and double kinks of flux lines, can be pinned more effectively by the BaZrO nano-particles, so that the Jc enhances for high magnetic fields and high temperature. In addition, the inverse correlation between Jc and n-value appears at high temperature in increasing magnetic field for the film with correlated rows of the nano-particles which might be curved off the c-axis. These suggest that the hybrid flux pinning depends not only on the combination of one-dimensional (1D) and three-dimensional pinning centers (3D-PCs) but also on the size and the spatial distribution of the 3D-PCs.
Hayashi, Yukio; Pirozhkov, A. S.; Kando, Masaki; Ogura, Koichi; Kotaki, Hideyuki; Kiriyama, Hiromitsu; Okada, Hajime; Goto, Hideki*; Nishikawa, Tadashi*
Laser and Particle Beams, 31(3), p.419 - 425, 2013/09
Times Cited Count：1 Percentile：4.61(Physics, Applied)To increase X-ray photon number generated by laser-cluster interaction, it is important to understand the dependence of X-ray generation on cluster size. We carried out Xe K-shell X-ray generation using a conical nozzle with Xe clusters, the radius of which was controllable by adjusting the backing pressure. The experiment clarifies the result that the Xe K-shell X-ray photon number increases with increasing cluster radius from 8 to 12 nm, and saturates at the radius between 12 and 17 nm. We also investigated the Xe K-shell X-ray photon number dependence on laser intensity, and found that the threshold laser intensity of the Xe K-shell X-ray generation exists between 2
10
and 510
W/cm
.
-ray simultaneous imaging by using a Si/CdTe Compton cameraSuzuki, Yoshiyuki*; Yamaguchi, Mitsutaka; Odaka, Hirokazu*; Shimada, Hirofumi*; Yoshida, Yukari*; Torikai, Kota*; Sato, Takahiro; Arakawa, Kazuo*; Kawachi, Naoki; Watanabe, Shigeki; et al.
Radiology, 267(3), p.941 - 947, 2013/06
Times Cited Count：23 Percentile：64.83(Radiology, Nuclear Medicine & Medical Imaging)Yamaguchi, Mitsutaka; Kawachi, Naoki; Kamiya, Tomihiro; Sato, Takahiro; Suzui, Nobuo; Fujimaki, Shu; Odaka, Hirokazu*; Ishikawa, Shinnosuke*; Kokubun, Motohide*; Watanabe, Shin*; et al.
JAEA-Review 2011-043, JAEA Takasaki Annual Report 2010, P. 145, 2012/01
no abstracts in English
Yamaguchi, Mitsutaka; Kawachi, Naoki; Suzui, Nobuo; Fujimaki, Shu; Kamiya, Tomihiro; Odaka, Hirokazu*; Ishikawa, Shinnosuke*; Kokubun, Motohide*; Watanabe, Shin*; Takahashi, Tadayuki*; et al.
Nuclear Instruments and Methods in Physics Research A, 648(Suppl.1), p.S2 - S7, 2011/08
Times Cited Count：2 Percentile：19.86(Instruments & Instrumentation)We are constructing a three-dimensional imaging system for medical and biological applications. The system will allow simultaneous imaging at high spatial and energy resolutions across a wide energy range, from several tens of keV to a few MeV. In this work, one prototype head module have been developed for a multi-head Si/CdTe Compton camera system. The performance of the prototype was evaluated with a sealed Ba-133 radiation source. The experiments confirmed that the imaging results were consistent with actual source position. In addition to the resolution for the parallel directions to the detector surface, the position resolution was evaluated for the depth direction at a point in near region of the head-module. These position resolutions were well reproduced by Monte Carlo simulation results.
Yamaguchi, Mitsutaka; Kawachi, Naoki; Kamiya, Tomihiro; Suzui, Nobuo; Fujimaki, Shu; Odaka, Hirokazu*; Ishikawa, Shinnosuke*; Kokubun, Motohide*; Watanabe, Shin*; Takahashi, Tadayuki*; et al.
2010 IEEE Nuclear Science Symposium Conference Record (CD-ROM), p.2004 - 2007, 2010/10
Ishikawa, Norito; Ohara, Kota; Ota, Yasuyuki*; Michikami, Osamu*
Nuclear Instruments and Methods in Physics Research B, 268(19), p.3273 - 3276, 2010/10
Times Cited Count：11 Percentile：56.76(Instruments & Instrumentation)In this experiment, CeO thin films are irradiated with 200 MeV Au to investigate the damage created by electronic energy deposition. The damage is studied by Raman spectroscopy.
irradiated with high-energy ions by means of X-ray diffraction measurementIshikawa, Norito; Chimi, Yasuhiro; Michikami, Osamu*; Ota, Yasuyuki*; Ohara, Kota; Lang, M.*; Neumann, R.*
Nuclear Instruments and Methods in Physics Research B, 266(12-13), p.3033 - 3036, 2008/06
Times Cited Count：43 Percentile：92.28(Instruments & Instrumentation)Cerium dioxide films are irradiated with high-energy heavy ions with the energy range of 150 MeV to 2.7 GeV, and X-ray diffraction profile is examined. As a result, the data can be explained by creation of nanometer-size ion track with disordered lattice structure, and the ion track is oxygen deficient.
Higuchi, Hidekazu; Osugi, Takeshi; Nakashio, Nobuyuki; Momma, Toshiyuki; Tohei, Toshio; Ishikawa, Joji; Iseda, Hirokatsu; Mitsuda, Motoyuki; Ishihara, Keisuke; Sudo, Tomoyuki; et al.
JAEA-Technology 2007-038, 189 Pages, 2007/07
JAEA-Technology-2007-038-01.pdf:15.13MBJAEA-Technology-2007-038-02.pdf:38.95MBJAEA-Technology-2007-038-03.pdf:48.42MBJAEA-Technology-2007-038-04.pdf:20.53MBJAEA-Technology-2007-038-05.pdf:10.44MB
The Advanced Volume Reduction Facilities (AVRF) is constructed to manufacture the waste packages of radioactive waste for disposal in the Nuclear Science Research Institute of the Japan Atomic Energy Agency. The AVRF is constituted from two facilities. The one is the Waste Size Reduction and Storage Facility (WSRSF) which is for reducing waste size, sorting into each material and storing the waste package. The other is the Waste Volume Reduction Facility (WVRF) which is for manufacturing the waste package by volume reducing treatment and stabilizing treatment. WVRF has an induction melting furnace, a plasma melting furnace, an incinerator, and a super compactor for treatment. In this report, we summarized about the basic concept of constructing AVRF, the constitution of facilities, the specifications of machineries and the state of trial operation until March of 2006.
Shiina, Yasuaki; Ishikawa, Kota*; Hishida, Makoto*
Nihon Kikai Gakkai Rombunshu, B, 73(728), p.1045 - 1051, 2007/04
Heat transfer characteristics near the critical Rayleigh number for the onset of natural convection of horizontal anisotropic porous fluid layer heated from below with thin cylindrical rods inserted with high porosity above 0.822 to unity were studied by an analysis and an experiment. The critical Rayleigh number and dependence of Nusselt number on the Rayleigh number were analysed by linear stability theory and series expansion method on the basis of Darcy flow assumption. Critical Rayleigh number, increased with decrease in the porosity, was higher for the experiment than for the analysis but the difference was decreased with decrease in Darcy number. Experimental Nusselt number was considerably decreased with decrease in the porosity near unity although is rather same as the case of Benard convection without cylindrical rods. The experimental Nusselt number can be expressed by one correlation curve when Nusselt number is plotted against Darcy number of the present experiment was rather large to satisfy Darcy flow assumption. Experiment shows that Darcy flow assumption will be satisfied for Darcy number.
Shiina, Yasuaki; Hishida, Makoto*; Ishikawa, Kota*
Nihon Kikai Gakkai Tohoku Shibu Dai-42-Ki Sokai, Koenkai Koen Rombunshu, p.137 - 138, 2007/03
no abstracts in English
Shiina, Yasuaki; Ishikawa, Kota*; Hishida, Makoto*; Tanaka, Gaku*
Nihon Kikai Gakkai 2006-Nendo Nenji Taikai Koen Rombunshu, Vol.3, p.173 - 174, 2006/09
no abstracts in English
