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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：33.61(Engineering, Multidisciplinary)
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：40.64(Physics, Nuclear)
Sr
NiO
studied by neutron diffractionKajimoto, Ryoichi; Nakajima, Kenji; Fujita, Masaki*; Ishikado, Motoyuki*; Torii, Shuki*; Ishikawa, Yoshihisa*; Miao, P.*; Kamiyama, Takashi*
Journal of the Physical Society of Japan, 88(11), p.114602_1 - 114602_6, 2019/11
Times Cited Count：0 Percentile：0.00(Physics, Multidisciplinary)Kataoka, Noriaki*; Nakajima, Junya; Miwa, Kazuji; Hirota, Seiko*; Tsubota, Yoichi; Yamada, Ryohei; Fujimichi, Yuki*; Ishikawa, Junya*; Sunaoshi, Masaaki*
Hoken Butsuri (Internet), 54(2), p.140 - 145, 2019/06
It is the written report of the joint meeting of young researchers in the field of radiation protection and radiation biology.
Kawamura, Hideyuki; Furuno, Akiko; Kobayashi, Takuya; In, Teiji*; Nakayama, Tomoharu*; Ishikawa, Yoichi*; Miyazawa, Yasumasa*; Usui, Norihisa*
Journal of Environmental Radioactivity, 180, p.36 - 58, 2017/12
Times Cited Count：12 Percentile：35.86(Environmental Sciences)This study simulates the oceanic dispersion of Fukushima-derived Cs-137 by an oceanic dispersion model and multiple oceanic general circulation models. The models relatively well reproduced the observed Cs-137 concentrations in the coastal, offshore, and open oceans. Multiple simulations in the coastal, offshore, and open oceans consistently suggested that Cs-137 dispersed along the coast in the north-south direction during the first few months post-disaster, and were subsequently dispersed offshore by the Kuroshio Current and Kuroshio Extension. Quantification of the Cs-137 amounts suggested that Cs-137 actively dispersed from the coastal and offshore oceans to the open ocean, and from the surface layer to the deeper layers in the North Pacific.
Nakajima, Kenji; Kawakita, Yukinobu; Ito, Shinichi*; Abe, Jun*; Aizawa, Kazuya; Aoki, Hiroyuki; Endo, Hitoshi*; Fujita, Masaki*; Funakoshi, Kenichi*; Gong, W.*; et al.
Quantum Beam Science (Internet), 1(3), p.9_1 - 9_59, 2017/12
The neutron instruments suite, installed at the spallation neutron source of the Materials and Life Science Experimental Facility (MLF) at the Japan Proton Accelerator Research Complex (J-PARC), is reviewed. MLF has 23 neutron beam ports and 21 instruments are in operation for user programs or are under commissioning. A unique and challenging instrumental suite in MLF has been realized via combination of a high-performance neutron source, optimized for neutron scattering, and unique instruments using cutting-edge technologies. All instruments are/will serve in world-leading investigations in a broad range of fields, from fundamental physics to industrial applications. In this review, overviews, characteristic features, and typical applications of the individual instruments are mentioned.
Kamachi, Masafumi*; Ishikawa, Yoichi*; Kawamura, Hideyuki; Maximenko, N.*; Hafner, J.*; MacFadyen, A.*
Techno-Ocean 2016 (Techno-Ocean), p.599 - 602, 2016/10
The tsunami that followed the Great East Japan Earthquake in March 2011 caused a large amount of debris to flow out into the North Pacific, mainly from the Tohoku district, Japan. We conducted drift simulations to monitor and predict the trajectory of the tsunami debris. The results suggested that the tsunami debris was mainly transported eastward by the Kuroshio Extension and prevailing westerly winds, spreading in a north-south direction by ocean eddies and storms. As for the tsunami debris with high buoyancy, it was shown to be strongly influenced by ocean surface winds as well as ocean currents, reaching the west coast of the North American continent around the fall of 2011.
Takechi, Manabu; Matsunaga, Go; Sakurai, Shinji; Sasajima, Tadayuki; Yagyu, Junichi; Hoshi, Ryo*; Kawamata, Yoichi; Kurihara, Kenichi; JT-60SA Team; Nishikawa, T.*; et al.
Fusion Engineering and Design, 96-97, p.985 - 988, 2015/10
Times Cited Count：12 Percentile：65.51(Nuclear Science & Technology)Kobayashi, Takuya; In, Teiji*; Ishikawa, Yoichi*
Journal of Nuclear Science and Technology, 52(6), p.769 - 772, 2015/06
Times Cited Count：1 Percentile：9.26(Nuclear Science & Technology)Ocean diffusion concentration maps were developed to gain an understanding of the migration behavior of contaminated water leaking from the Fukushima Dai-ichi Nuclear Power Plant. We used ensemble mean values to define the semi-climatological seasonal field in our calculations of the trajectories of the contaminated water. The maps were validated by conducting actual release events in two different seasons. The results showed that despite their simplicity, the proposed methods yield relatively good results.
Ajimura, Shuhei*; Bezerra, T. J. C.*; Chauveau, E.*; Enomoto, T.*; Furuta, Hisataka*; Harada, Masahide; Hasegawa, Shoichi; Hiraiwa, T.*; Igarashi, Yoichi*; Iwai, Eito*; et al.
Progress of Theoretical and Experimental Physics (Internet), 2015(6), p.063C01_1 - 063C01_19, 2015/06
Times Cited Count：6 Percentile：44.19(Physics, Multidisciplinary)The J-PARC E56 experiment aims to search for sterile neutrinos at the J-PARC Materials and Life Science Experimental Facility (MLF). In order to examine the feasibility of the experiment, we measured the background rates of different detector candidate sites, which are located at the third floor of the MLF, using a detector consisting of plastic scintillators with a fiducial mass of 500 kg. The gammas and neutrons induced by the beam as well as the backgrounds from the cosmic rays were measured, and the results are described in this article.
Kawamura, Hideyuki; Kobayashi, Takuya; Nishikawa, Shiro*; Ishikawa, Yoichi*; Usui, Norihisa*; Kamachi, Masafumi*; Aso, Noriko*; Tanaka, Yusuke*; Awaji, Toshiyuki*
Global Environmental Research (Internet), 18(1), p.81 - 96, 2014/09
A drift simulation of tsunami debris flushed out from the Tohoku district, Japan, into the North Pacific due to the tsunami on March 11, 2011, has been conducted to monitor and forecast the drift path over the North Pacific. Results showed that tsunami debris was first transported eastward by the intense Kuroshio Extension and westerly, spreading in the north and south directions by both an energetic ocean eddy and a storm track over the ocean. Tsunami debris with larger windage was transported over the North Pacific by ocean surface wind rather than ocean current and arrived at the west coast of the North American Continent in the fall of 2011. Tsunami debris located near the North American Continent migrated, associated with the basin-scale seasonal change in the atmospheric pressure pattern. Our forecast run suggested that the tsunami debris belt will be formed from the North American Continent in the east to the Philippines in the west.
Kawamura, Hideyuki; Kobayashi, Takuya; Furuno, Akiko; Usui, Norihisa*; Kamachi, Masafumi*; Nishikawa, Shiro*; Ishikawa, Yoichi*
Proceedings of 19th Pacific Basin Nuclear Conference (PBNC 2014) (USB Flash Drive), 7 Pages, 2014/08
Numerical simulations on oceanic dispersion of the radioactive cesium in the North Pacific from March 2011 to September 2013 were conducted to clarify the concentration of the radioactive cesium released from the Fukushima Daiichi Nuclear Power Plant. We implemented the oceanic dispersion simulations with two independent ocean reanalysis dataset. It was suggested that the 
Cs concentration in the North Pacific was lower than the pre-Fukushima background level about two years after the Fukushima disaster. The intercomparison revealed that meso-scale eddies in the Kuroshio Extension region may have efficiently diluted the radioactive cesium concentration at the sea surface. In addition, it was suggested that the enhanced downward current accompanied by the meso-scale eddies played an important role in transporting the radioactive cesium into the intermediate layer.
Hiraishi, Masatoshi*; Iimura, Soshi*; Kojima, Kenji*; Yamaura, Junichi*; Hiraka, Haruhiro*; Ikeda, Kazutaka*; Miao, P.*; Ishikawa, Yoshihisa*; Torii, Shuki*; Miyazaki, Masanori*; et al.
Nature Physics, 10(4), p.300 - 303, 2014/04
Times Cited Count：105 Percentile：95.12(Physics, Multidisciplinary)Kawamura, Hideyuki; Kobayashi, Takuya; Furuno, Akiko; In, Teiji*; Ishikawa, Yoichi*; Nakayama, Tomoharu*; Shima, Shigeki*; Awaji, Toshiyuki*
Reports of Research Institute for Applied Mechanics, Kyushu University, (143), p.111 - 117, 2012/09
Because of the Fukushima Dai-ichi Nuclear Power Plant disaster, some radionuclides were released into the ocean from the Fukushima Dai-ichi Nuclear Power Plant. In response to this situation, numerical experiments were carried out at Japan Atomic Energy Agency using an oceanic dispersion model and an ocean general circulation model to estimate an effect of the radionuclides on marine environment. It was suggested that the radionuclides deposited from the atmosphere mainly in the middle of March after the disaster spread over a comparatively wide area of the Pacific Ocean east of Japan. On the other hand the radionuclides directly released into the ocean from the Fukushima Dai-ichi Nuclear Power Plant were carried along the coast and then spread along the Kuroshio extension.
I and Cs discharged into the ocean because of the Fukushima Daiichi Nuclear Power Plant disasterKawamura, Hideyuki; Kobayashi, Takuya; Furuno, Akiko; In, Teiji*; Ishikawa, Yoichi*; Nakayama, Tomoharu*; Shima, Shigeki*; Awaji, Toshiyuki*
Journal of Nuclear Science and Technology, 48(11), p.1349 - 1356, 2011/11
Times Cited Count：186 Percentile：99.77(Nuclear Science & Technology)Numerical experiments were carried out to predict the spreading of I and Cs released into the ocean due to the Fukushima Daiichi Nuclear Power Plant incident. Results in the numerical experiments were in good agreement with the concentrations of I and Cs in the monitoring data. It was suggested that the high I concentration detected in the young lancefish caught off Kitaibaraki city was due to the deposition from the atmosphere. The numerical experiments suggest that the deposition of radionuclides released into the atmosphere in the middle March largely effected the concentrations of radionuclides east of Japan in the Pacific Ocean.
Kobayashi, Takuya; In, Teiji*; Ishikawa, Yoichi*; Kawamura, Hideyuki; Nakayama, Tomoharu*; Shima, Shigeki*; Awaji, Toshiyuki*; Togawa, Orihiko
Progress in Nuclear Science and Technology (Internet), 2, p.682 - 687, 2011/10
When the reprocessing plant is in routine operation, radionuclides are released to the coastal ocean as scheduled. Released radionuclides migrate in the ocean by physical, chemical and biological processes. Thus, for environmental safety, it is important to understand the migration behavior due to routine releases of radionuclides to the coastal ocean from the reprocessing plant. A numerical simulation model system that consists of an ocean general circulation model and a particle random-walk model to describe the radionuclide migration behavior in Rokkasho coastal region has been developed. The particle random-walk model, SEA-GEARN, calculates the radionuclides migration in the ocean. The system has been applied to simulate the nowcast of Rokkasho coastal region in 2007 and hypothetical radionuclide release has been carried out.
Ishikawa, Masao; Kondoh, Takashi; Okawa, Kiyofumi*; Fujita, Kyoichi*; Yamauchi, Michinori*; Hayakawa, Atsuro*; Nishitani, Takeo; Kusama, Yoshinori
Review of Scientific Instruments, 81(10), p.10D308_1 - 10D308_3, 2010/10
Times Cited Count：2 Percentile：13.01(Instruments & Instrumentation)Microfission chambers (MFCs) will provide total neutron source strength in ITER. The MFC is a pencil-sized gas counter containing the fissile material, 
U. The MFCs will be installed behind blanket modules in the vacuum vessel (VV). Double coaxial mineral insulated (MI) cables will carry signals from the MFCs to the upper port. Though the MI cables will be installed at a factory of the vacuum vessel or ITER assembly hall, detectors with U will be installed to the vacuum vessel at the tokamak pit. Then, the MI cable should be connected in the vacuum vessel. In this work, the connection of the MI cable with the MFC was conceptually designed. The MI cable should be also installed with small curvature radius (R) of 100 
200 mm to avoid the VV structure and other diagnostics. So, the vending test of the MI cable was conducted. As a result, damages leak, electrical disconnection and the change in insulation resistance have not been observed at R = 100 mm.
Yui, Mikazu; Ishikawa, Hirohisa; Watanabe, Atsuo*; Yoshino, Kyoji*; Umeki, Hiroyuki; Hioki, Kazumasa; Naito, Morimasa; Seo, Toshihiro; Makino, Hitoshi; Oda, Chie; et al.
JAEA-Research 2010-015, 106 Pages, 2010/05
JAEA-Research-2010-015.pdf:13.58MB
This report summarizes the activity of Phase I of Waste Management Working Group of the United States - Japan Joint Nuclear Energy Action Plan started in 2007. The working group focused on consolidation of the existing technical basis between the U.S. and Japan and the joint development of a plan for future collaborative activities. Firstly, the political/regulatory frameworks related to nuclear fuel cycles in both countries were reviewed. The various advanced fuel cycle scenarios in both countries were surveyed and summarized. Secondly, the waste management/disposal system optimization was discussed. Repository system concepts for the various classifications of nuclear waste were reviewed and summarized, then disposal system optimization processes and techniques were reviewed, and factors to consider in future repository design optimization activities were also discussed. Finally the potential collaboration areas and activities related to the optimization problem were extracted.
Matsui, Yoshinori; Takahashi, Hiroyuki; Yamamoto, Masaya; Nakata, Masahito; Yoshitake, Tsunemitsu; Abe, Kazuyuki; Yoshikawa, Katsunori; Iwamatsu, Shigemi; Ishikawa, Kazuyoshi; Kikuchi, Taiji; et al.
JAEA-Technology 2009-072, 144 Pages, 2010/03
JAEA-Technology-2009-072.pdf:45.01MB
"R&D Project on Irradiation Damage Management Technology for Structural Materials of Long-life Nuclear Plant" was carried out from FY2006 in a fund of a trust enterprise of the Ministry of Education, Culture, Sports, Science and Technology. The coupled irradiations or single irradiation by JOYO fast reactor and JRR-3 thermal reactor were performed for about two years. The irradiation specimens are very important materials to establish of "Evaluation of Irradiation Damage Indicator" in this research. For the acquisition of the examination specimens irradiated by the JOYO and JRR-3, we summarized about the overall plan, the work process and the results for the study to utilize these reactors and some facilities of hot laboratory (WASTEF, JMTR-HL, MMF and FMF) of the Oarai Research-and-Development Center and the Nuclear Science Research Institute in the Japan Atomic Energy Agency.
Kobayashi, Takuya; In, Teiji*; Ishikawa, Yoichi*; Matsuura, Yasutaka*; Shima, Shigeki*; Nakayama, Tomoharu*; Awaji, Toshiyuki*; Kawamura, Hideyuki; Togawa, Orihiko
Nihon Genshiryoku Gakkai Wabun Rombunshi, 7(2), p.112 - 126, 2008/06
The radionuclides migration forecasting system in the off Shimokita region has been developed to predict the routine and accidental releases of liquid radioactive wastes during the operations of a spent nuclear fuel reprocessing plant in Aomori prefecture, Japan. The results obtained from the case studies are as follows; (1) The ocean general circulation model by using the techniques of data assimilation and nesting reproduced well the flow pattern of a coastal area. (2) The estimated internal dose due to ingestion of marine products from hypothetical release of 
H was 0.45 
Sv/y. (3) The results of hypothetical release of Cs showed that about four percent of the whole deposited on the seabed after a 60-day calculation. The concentration of Cs of hypothetical release from the off Shimokita region is the same or less than that of global fallout measured at the same area.
