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Kitazato, Kohei*; Milliken, R. E.*; Iwata, Takahiro*; Abe, Masanao*; Otake, Makiko*; Matsuura, Shuji*; Takagi, Yasuhiko*; Nakamura, Tomoki*; Hiroi, Takahiro*; Matsuoka, Moe*; et al.
Nature Astronomy (Internet), 5(3), p.246 - 250, 2021/03
Times Cited Count：43 Percentile：96.93(Astronomy & Astrophysics)Here we report observations of Ryugu's subsurface material by the Near-Infrared Spectrometer (NIRS3) on the Hayabusa2 spacecraft. Reflectance spectra of excavated material exhibit a hydroxyl (OH) absorption feature that is slightly stronger and peak-shifted compared with that observed for the surface, indicating that space weathering and/or radiative heating have caused subtle spectral changes in the uppermost surface. However, the strength and shape of the OH feature still suggests that the subsurface material experienced heating above 300 
C, similar to the surface. In contrast, thermophysical modeling indicates that radiative heating does not increase the temperature above 200 C at the estimated excavation depth of 1 m, even if the semimajor axis is reduced to 0.344 au. This supports the hypothesis that primary thermal alteration occurred due to radiogenic and/or impact heating on Ryugu's parent body.
Myagmarjav, O.; Iwatsuki, Jin; Tanaka, Nobuyuki; Noguchi, Hiroki; Kamiji, Yu; Ioka, Ikuo; Kubo, Shinji; Nomura, Mikihiro*; Yamaki, Tetsuya*; Sawada, Shinichi*; et al.
International Journal of Hydrogen Energy, 44(35), p.19141 - 19152, 2019/07
Times Cited Count：16 Percentile：49.6(Chemistry, Physical)Kitazato, Kohei*; Milliken, R. E.*; Iwata, Takahiro*; Abe, Masanao*; Otake, Makiko*; Matsuura, Shuji*; Arai, Takehiko*; Nakauchi, Yusuke*; Nakamura, Tomoki*; Matsuoka, Moe*; et al.
Science, 364(6437), p.272 - 275, 2019/04
Times Cited Count：259 Percentile：99.73(Multidisciplinary Sciences)The near-Earth asteroid 162173 Ryugu, the target of Hayabusa2 sample return mission, is believed to be a primitive carbonaceous object. The Near Infrared Spectrometer (NIRS3) on Hayabusa2 acquired reflectance spectra of Ryugu's surface to provide direct measurements of the surface composition and geological context for the returned samples. A weak, narrow absorption feature centered at 2.72 micron was detected across the entire observed surface, indicating that hydroxyl (OH)-bearing minerals are ubiquitous there. The intensity of the OH feature and low albedo are similar to thermally- and/or shock-metamorphosed carbonaceous chondrite meteorites. There are few variations in the OH-band position, consistent with Ryugu being a compositionally homogeneous rubble-pile object generated from impact fragments of an undifferentiated aqueously altered parent body.
Hidaka, Akihide; Nakano, Yoshihiro; Watanabe, Yoko; Arai, Nobuyoshi; Sawada, Makoto; Kanaizuka, Seiichi*; Katogi, Aki; Shimada, Mayuka*; Ishikawa, Tomomi*; Ebine, Masako*; et al.
JAEA-Review 2016-011, 208 Pages, 2016/07
JAEA-Review-2016-011-01.pdf:33.85MBJAEA-Review-2016-011-02.pdf:27.68MB
JAEA has been conducting the Instructor Training Program (ITP) since 1996 under the auspices of MEXT to contribute to human resource development in currently 11 Asian countries in the field of radiation utilization for seeking peaceful use of nuclear energy. ITP consists of Instructor Training Course (ITC), Follow-up Training Course (FTC) and Nuclear Technology Seminars. In the ITP, trainings or seminars relating to technology for nuclear utilization are held in Japan by inviting nuclear related people from Asian countries to Japan and after that, the past trainees are supported during FTC by dispatching Japanese specialists to Asian countries. News Letter is also prepared to provide the broad range of information obtained through the trainings for local people near NPPs in Japan. The present report describes the activities of FY2014 ITP and future challenges for improving ITP more effectively.
Watanabe, Yoko; Arai, Nobuyoshi; Sawada, Makoto; Kanaizuka, Seiichi; Shimada, Mayuka*; Ishikawa, Tomomi*; Nakamura, Kazuyuki
JAEA-Review 2015-026, 38 Pages, 2015/11
JAEA-Review-2015-026.pdf:10.55MB
JAEA has conducted Nuclear Technology Seminar for Asian countries which plan to introduce NPP, in order to increase the number of engineers and specialists. The Nuclear Technology Seminar on the Basic Radiation Knowledge for School Education Course was launched in 2012 due to increased recognition of the dissemination of the basic knowledge of radiation in public and education sectors as an important issue in the aftermath of the Fukushima Dai-ichi NPP Accident. In response to the requests of past participants, a new exercise "Joint experiment with high school students" was introduced from 2014 to provide an international learning experience for the course participants and the local Japanese students. A new learning material was also developed to help participants to study the basics of radiation in English. All the course activities including the details of preparatory process and course evaluation were described in this report.
Hidaka, Akihide; Nakamura, Kazuyuki; Watanabe, Yoko; Yabuuchi, Yukiko; Arai, Nobuyoshi; Sawada, Makoto; Yamashita, Kiyonobu; Sawai, Tomotsugu; Murakami, Hiroyuki
Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 9 Pages, 2015/05
Nakajima, Makoto*; Seno, Shoji*; Onoe, Hironori; Ishibashi, Masayuki; Saegusa, Hiromitsu; Sawada, Atsushi
Dai-42-Kai Gamban Rikigaku Ni Kansuru Shimpojiumu Koenshu (CD-ROM), p.107 - 112, 2014/01
Japan Atomic Energy Agency is proceeding with the Mizunami Underground Research Laboratory Project in order to establish comprehensive techniques for the investigation, analysis and assessment of the deep geological environment in fractured crystalline rock for geological disposal of high level radioactive wastes. We have carried out discrete fracture network modeling, groundwater flow and particle tracking simulation in order to understand the important factors for the solute transport characterizations. In this paper, a method for estimating hydraulic parameter of discrete fracture network model based on in-situ data at underground gallery are described.
Sawada, Sumiyuki*; Nakayama, Masashi; Ishikawa, Makoto
JAEA-Data/Code 2013-018, 25 Pages, 2013/12
JAEA-Data-Code-2013-018.pdf:3.18MB
JAEA-Data-Code-2013-018-appendix(CD-ROM).zip:105.32MB
The Horonobe Underground Research Laboratory (URL) Project has being pursued by the Japan Atomic Energy Agency (JAEA) to enhance the reliability of relevant investigations of the deep geological environment within the host sedimentary formations at Horonobe, northern Hokkaido. Horonobe URL will be excavated three shafts (Ventilation shaft, East shaft and West shaft) connected by three drifts (G.L -140m, G.L -250m and G.L -350m) at the time of completion. In the construction area, the sedimentary rock has spread. And the construction position is located in the stratum boundary of Koetoi formation and the Wakkanai formation. According to the investigation from the ground, existence of the fault with springwater and of the methane separated from groundwater was confirmed. From the viewpoint of the security under construction and the control of the amount of springwater from the URL, pre-grouting was carried out. This report summarizes the construction data of the pre-grouting acquired at the Ventilation Shaft.
Sawada, Makoto; Sasaki, Kazuichi; Nishida, Masaaki
Proceedings of International Conference on Fast Reactors and Related Fuel Cycles (FR 2009) (CD-ROM), 12 Pages, 2012/00
Japan is aiming at starting commercial operation of a demonstration FBR around 2025 in the FaCT (Fast Reactor Cycle Technology Development) project. To prepare for such as the new FBR age, INITC has established a total of 27 JAEA staff training courses based on the teachings obtained from the Monju leak accident, regarding to FBR operation technology, sodium handling technology, maintenance technology and FBR plant system engineering technology, and also has been conducting energy environmental education for from under high school students to graduate students of the whole country including local universities. In addition, INITC aims become a central of excellent (COE) of the international technology training in Asia through the international educational training programs sponsored by MEXT. The variety of the activities of educational training mentioned above will contribute to the development of the human resource in Japan and abroad, towards the next generation age.
=3 levels observed on MSE spectra of LHD plasmaIwamae, Atsushi; Sakaue, Atsushi*; Atake, Makoto*; Sawada, Keiji*; Goto, Motoshi*; Morita, Shigeru*
Plasma Physics and Controlled Fusion, 51(11), p.115004_1 - 115004_15, 2009/11
Times Cited Count：6 Percentile：23.87(Physics, Fluids & Plasmas)Ijiri, Yuji*; Saegusa, Hiromitsu; Sawada, Atsushi; Ono, Makoto*; Watanabe, Kunio*; Karasaki, Kenji*; Doughty, C.*; Shimo, Michito*; Fumimura, Kenichi*
Journal of Contaminant Hydrology, 103(3-4), p.168 - 181, 2009/01
Times Cited Count：9 Percentile：30.23(Environmental Sciences)Qualitative evaluation of the effects of uncertainties originating from scenario development, conceptual models, and parameter values is an important subject in the area of safety assessment for high-level nuclear waste disposal. In this study, regional-scale groundwater flow analyses for the Tono area, Japan were conducted using three continuous models which were designed to handle heterogeneous porous media. We evaluated the simulation results to quantitatively analyze uncertainties originating from conceptual models. We found that uncertainties originating from conceptual models (1) greatly depend on boundary conditions and hydrological structures to be modeled, which are assigned by modelers, and (2) are larger than uncertainties originating from the variance in realizations of the Monte Carlo method in stochastic modeling.
Sawada, Makoto; Sakurai, Naoto
Proceedings of International Symposium on Symbiotic Nuclear Power Systems for 21st Century (ISSNP) (CD-ROM), p.275 - 283, 2007/07
The prototype FBR Monju which caused a sodium leak accident in Dec. 1995 is now under remodeling to attain its re-initial criticality in 2008. The success or failure of its safety operation is an important issue which influences development of nuclear fuel cycle. So, a high quality educational training is strongly required in order to assure its future safety operation. Based on the teachings learned from the accident, Monju has revised its educational training structure extensively such as, a new building a framework of educational training, a new open of Monju FBR Training School, a reinforcement of simulator training, etc.. A total of 29 established training courses, based on the mentioned above improvements, have been conducting towards Monju restarting.
Ijiri, Yuji*; Saegusa, Hiromitsu; Sawada, Atsushi; Nakano, Katsushi; Ono, Makoto*
Chikasui Ryudo Kaiseki To Moderuka Ni Kansuru Shimpojium Happyo Rombunshu, p.67 - 76, 2007/01
no abstracts in English
Miyahara, Kaname; Yoshikawa, Hideki; Oi, Takao; Shibata, Masahiro; Sawada, Atsushi; Sasamoto, Hiroshi; Iijima, Kazuki; Maekawa, Keisuke; Kawamura, Makoto; Kato, Tomoko; et al.
JAEA-Review 2006-015, 29 Pages, 2006/03
JAEA-Review-2006-015.pdf:4.58MB
This report is to outline a 5-year plan of research and development (R&D) for performance assessment of geological disposal of high-level radioactive waste in JAEA. This 5-year plan is based on JAEA's mid-term plan which follows the R&D policy specified in "Framework for Nuclear Energy Policy" issued by Japan Atomic Energy Commission. Moreover, research plans for safety regulation issued by Nuclear Safety Commission of Japan should be taken into account. The contents of this 5-year plan follows a framework of R&D issues for performance assessment field established in "the R&D map", i.e. the mid and long term R&D plan for geological disposal of high-level radioactive waste, developed by JNC (predecessor of JAEA) and other relevant R&D organizations. In each research plan, objectives based on the necessity and the significance of the research plan are clarified in the section of "Objectives and the past progresses", with summarizing the progresses of H12: Project to establish the scientific and technical basis for HLW disposal in Japan (Second Progress Report), and H17: Development and management of the technical knowledge base for the geological disposal of HLW (H17 report). In addition, next five year plan is described in the section of "5-year plan (up to Fiscal year Heisei-22)".
Makino, Hitoshi; Wakasugi, Keiichiro; Sawada, Atsushi; Kawamura, Makoto; Ebashi, Takeshi
Hoshasei Haikibutsu Anzen Kenkyu Nenji Keikaku (Heisei-13-Nendo
Heisei-17-Nendo) Kenkyu Seika Hokokushu, p.130 - 140, 2006/03
no abstracts in English
Watanabe, Tomoo; Ozawa, Kazumasa; Otsuka, Jiro; Sasaki, Kazuichi; Sawada, Makoto
JNC TN4440 2005-001, 40 Pages, 2005/07
JNC-TN4440-2005-001.pdf:1.85MB
no abstracts in English
Koyagishi, Naoki; Sasaki, Kazuichi; Sawada, Makoto; Kawanishi, Tomotake*; Yoshida, Kazuo*
JNC TN4410 2005-002, 26 Pages, 2005/07
JNC-TN4410-2005-002.pdf:2.84MB
The prototype fast breeder reactor, Monju, has been performing deliberately the operation training which is composed of the regulated training required by the government and the self-training. The training used a full scope type simulator (MARS: Monju Advanced Reactor Simulator) plays an important role among of the above mentioned trainings and greatly contributes to the Monju operator training for Monju restarting. This report covers the activities of Monju operator training in 2005 FY, i.e the training results, modification and maintenance of the MARS.
Otsuka, Jiro; Kawanishi, Tomotake*; Koyagishi, Naoki; Sasaki, Kazuichi; Sawada, Makoto
JNC TN4410 2004-010, 12 Pages, 2005/03
JNC-TN4410-2004-010.pdf:2.34MB
None
Aoki, Tadao; Sawada, Makoto; Oshita, Hironori; Matsuno, Yoshiaki*; Kitano, Akihiro; KAMEI, Michiru*
JNC TN4520 2004-001, 350 Pages, 2004/09
JNC-TN4520-2004-001.pdf:36.76MB
none
Koyagishi, Naoki; Sasaki, Kazuichi; Sawada, Makoto; Kawanishi, Tomotake*; Yoshida, Kazuo*
JNC TN4410 2004-005, 32 Pages, 2004/09
JNC-TN4410-2004-005.pdf:8.02MB
The prototype fast breeder reactor, Monju, has been performing deliberately the operator training which is composed of the regulated training required by the government and the self-training. The training used a full scope type simulator (MARS: Monju Advanced Reactor Simulator) plays and important role among of the above mentioned trainings and greatly contributes to the Monju operator training for Monju restarting. This report covers the activities of Monju operator training in 2003 FY, i.e. the trainig results and the remodeling working of the MARS in progress since 1999.
