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Kawabata, Kuniaki; Sato, Noritaka*
Keisoku To Seigyo, 62(5), p.276 - 279, 2023/05
no abstracts in English
Takano, Kazuya; Oki, Shigeo; Doda, Norihiro; Chikazawa, Yoshitaka; Maeda, Seiichiro
Proceedings of 2023 International Congress on Advanced in Nuclear Power Plants (ICAPP 2023) (Internet), 7 Pages, 2023/04
The MOX fueled SMR-SFRs with lower linear heat rating of 100 W/cm and 50 W/cm, whereas the linear heat rating at rated power is around 400 W/cm in general, were designed to decrease the fuel temperature during its rated power state in order to pursue the inherent core safety for MOX fueled SMR-SFRs. The transient analyses for Anticipated Transient Without Scram (ATWS) events represented by an Unprotected Loss of Flow (ULOF) accident on the lower linear heat rating cores were performed considering their inherent feedback reactivity. Through the transient analysis, the inherent core safety performances for the lower linear heat rating cores were discussed based on the evaluated maximum coolant temperature and Cumulative Damage Fraction (CDF) as criteria to maintain the core and fuel integrity. The feasible design window for MOX fueled SMR-SFRs with the inherent core safety focusing on the linear heat rating was identified based on the transient analysis results.
Iwamoto, Chihiro*; Takamura, Masato*; Ueno, Kota*; Kataoka, Minami*; Kurihara, Ryo*; Xu, P. G.; Otake, Yoshie*
ISIJ International, 62(5), p.1013 - 1022, 2022/05
Times Cited Count：3 Percentile：22.53(Metallurgy & Metallurgical Engineering)Takata, Takashi; Aoyagi, Mitsuhiro; Sonehara, Masateru
IAEA-TECDOC-1972, p.224 - 234, 2021/08
Sodium fire is one of the key issues for plant safety of sodium-cooled fast reactor (SFR) regardless of its size. In general, a concrete structure, which includes free and bonging water inside, is used in a reactor building. Accordingly, water vapor will release from the concrete during sodium fire incident due to temperature increase resulting in a hydrogengeneration even in a dry air condition. The probability of hydrogen generation will increase in accordance with a decrease of a dimension of compartment that corresponds to a small and medium sized or modular reactor (SMR). A numerical investigation of a small leakage sodium pool fire has been carried out by changing a dimension of compartment. Furthermore, numerical challenges to enhance a prediction accuracy of hydrogen generation during sodium fire has also been discussed in the paper.
Xu, P. G.; Ikeda, Yoshimasa*; Hakoyama, Tomoyuki*; Takamura, Masato*; Otake, Yoshie*; Suzuki, Hiroshi
Journal of Applied Crystallography, 53(2), p.444 - 454, 2020/04
Times Cited Count：10 Percentile：69.05(Chemistry, Multidisciplinary)Ikeda, Yoshimasa*; Takamura, Masato*; Hakoyama, Tomoyuki*; Otake, Yoshie*; Kumagai, Masayoshi*; Suzuki, Hiroshi
Tetsu To Hagane, 104(3), p.138 - 144, 2018/03
Times Cited Count：5 Percentile：23.40(Metallurgy & Metallurgical Engineering)Neutron engineering diffraction is a powerful technique which provides the information of the micro structure of steels in bulk-average, while X-ray diffraction or Electron backscatter diffraction can provide information only from the surface layer. However, such measurement using neutron diffraction is typically performed in a large facility such as a reactor and a synchrotron, while a compact neutron source has never been used for this purpose. Authors have recently developed a neutron diffractometer installed in Riken Accelerator driven compact Neutron Source (RANS) and succeeded in the measurement of texture evolution of a steel sheet. In this study, we made an attempt to measure the volume fraction of retained austenite by RANS. Background noise was carefully eliminated in order to detect as many diffraction peaks as possible with low flux neutrons. The volume fraction was estimated by Rietveld analysis. The accuracy of the measurement result was discussed by comparing with those obtained by a large neutron facility (J-PARC TAKUMI). The volume fraction obtained by RANS with reasonable measurement time, i.e. 30 to 300 min, showed only 1 to 2 % discrepancies with those obtained in J-PARC. These comparisons suggest that neutron diffraction by RANS is capable of quantitative analysis of the volume fraction of crystal phases, showing the possibility of practical use of an in-house compact neutron source in the industry.
Ikeda, Yoshimasa*; Taketani, Atsushi*; Takamura, Masato*; Sunaga, Hideyuki*; Kumagai, Masayoshi*; Oba, Yojiro*; Otake, Yoshie*; Suzuki, Hiroshi
Nuclear Instruments and Methods in Physics Research A, 833, p.61 - 67, 2016/10
Times Cited Count：43 Percentile：96.07(Instruments & Instrumentation)A compact accelerator-based neutron source has been lately discussed on engineering applications such as transmission imaging and small angle scattering as well as reflectometry. However, nobody considers using it for neutron diffraction experiment because of its low neutron flux. In this study, therefore, the neutron diffraction experiments are carried out using Riken Accelerator-driven Compact Neutron Source (RANS), to clarify the capability of the compact neutron source for neutron engineering diffraction. The diffraction pattern from a ferritic steel was successfully measured by suitable arrangement of the optical system to reduce the background noise, and it was confirmed that the recognizable diffraction pattern can be measured by the large sampling volume with 10 mm in cubic for an acceptable measurement time, i.e. 10 minutes. The minimum resolution of the 110 reflection for RANS is approximately 2.5 % at 8 
s of the proton pulse width, which is insufficient to perform the strain measurement by neutron diffraction. The moderation time width at the wavelength corresponding to the 110 reflection is estimated to be approximately 30 s, which is the most dominant factor to determine the resolution. Therefore, refinements of the moderator system to decrease the moderation time are important to improve the resolution of the diffraction experiment using the compact neutron source. In contrast, the texture evolution due to plastic deformation was successfully observed by measuring a change in the diffraction peak intensity by RANS. Furthermore, the volume fraction of the austenite phase was also successfully evaluated by fitting the diffraction pattern using a Rietveld code. Consequently, RANS was proved to be capable for neutron engineering diffraction aiming for the easy access measurement of the texture and the amount of retained austenite.
Takamura, Masato*; Ikeda, Yoshimasa*; Sunaga, Hideyuki*; Taketani, Atsushi*; Otake, Yoshie*; Suzuki, Hiroshi; Kumagai, Masayoshi*; Hama, Takayuki*; Oba, Yojiro*
Journal of Physics; Conference Series, 734(Part B), p.032047_1 - 032047_4, 2016/08
Times Cited Count：5 Percentile：84.52(Physics, Applied)Neutron diffraction is well known to be a useful technique for measuring a bulk texture of metallic materials taking advantage of a large penetration depth of the neutron beam. However, this technique has not been widely utilized for the texture measurement because large facilities like a reactor or a large accelerator are required in general. In contrast, RANS (Riken Accelerator-driven Compact Neutron Source) has been developed as a neutron source which can be used easily in laboratories. In this study, texture evolution in steel sheets with plastic deformation was successfully measured using RANS. The results show the capability of the compact neutron source for the analysis of the crystal structure of metallic materials, which leads us to a better understanding of plastic deformation behavior.
Kimura, Yasuhisa; Hirano, Hiroshi; Watahiki, Masatoshi; Kuba, Meiji; Ishikawa, Shinichiro
Dekomisshoningu Giho, (52), p.45 - 54, 2015/09
The Plutonium Fuel Fabrication Facility (PFFF) of the Japan Atomic Energy Agency is now in its decommissioning phase. In the PFFF, terminated gloveboxes have been dismantled. Gloveboxes to be dismantled are surrounded by a plastic enclosure to prevent contamination from being spread into process room. Dismantling operations for gloveboxes are performed manually by workers, each wearing an air-feed suit. However, the mental and physical loads placed on workers wearing the air-feed suits are intensively high. Therefore, R&Ds on new dismantling technologies including utilization of heavy machines covered with plastic enclosure for anti-contamination have been started to reduce the potential risks associated with workers and decommissioning costs. In this paper, the status of decommissioning of the PFFF and the overview of developed dismantling technologies for 
-tight gloveboxes are described.
Arakawa, Kazuo
Genshiryoku Nenkan 2006-Nen Ban, p.125 - 126, 2005/10
no abstracts in English
Nakajima, Nobuya; Takahashi, Hiroki; Kusunoki, Tsuyoshi; Mitomo, Nobuo
JAERI-Tech 2005-057, 54 Pages, 2005/09
JAERI-Tech-2005-057.pdf:4.27MB
Availability using small reactor sited in deep underground cave was examined as a district heat supply system.From the viewpoint of a social acceptability, the contact points with a distributed small reactor system were examined to resolve a social structure-subject of a big city through investigation of the city environmental issue and city calamity. In order to estimate the scale of the heat source of a district heat supply system, a virtual city model was set up about 100,000 populations. It became clear that the heat can be supplied by installing two reactors with thermal-power 100MWt (MR-100G) in caves. Moreover, it turns out that the system will also function effectively for more than 40 years. The economic efficiency of this system was compared with the natural-gas boiler, and we confirmed that the district heat supply system by the small reactor is excellent especially for the case of long-term system operation.
Ito, Toshimichi; Kinoshita, Masataka*; Saito, Saneatsu*; Machiyama, Hideaki*; Shima, Shigeki*; Gasa, Shinichi*; Togawa, Orihiko; Okano, Masaharu*
JAERI-Research 2005-028, 121 Pages, 2005/09
JAERI-Research-2005-028.pdf:12.45MB
no abstracts in English
Arakawa, Kazuo
Genshiryoku Nenkan 2004-Nen Ban, p.196 - 197, 2003/11
no abstracts in English
Okubo, Tsutomu; Iwamura, Takamichi; Takeda, Renzo*; Moriya, Kumiaki*; Yamauchi, Toyoaki*; Aritomi, Masanori*
Nihon Kikai Gakkai 2003-Nendo Nenji Taikai Koen Rombunshu, Vol.3, p.245 - 246, 2003/08
A design study on a 300MWe class small Reduced-Moderation Water Reactor (RMWR) has been performed, based on the experienced LWR technology. The core can be cooled by the natural circulation and can achieve a conversion ratio of 1.01, a negative void reactivity coefficient, a core average burn-up of 65 GWd/t and a cycle length of 25 months. The system has been simplified as much as possible by introducing the passive safety components, in order to reduce the construction cost per electric power output overcoming “the scale demerit" for a small reactor comparing with the large one. The results show a 1.35 times higher cost than for the ABWR case, but suggest the possible lower cost when the effects such as the mass production are taken into account.
Takahashi, Hiroki; Nakajima, Nobuya; Kusunoki, Tsuyoshi
JAERI-Tech 2003-052, 59 Pages, 2003/06
JAERI-Tech-2003-052.pdf:5.95MB
The feasibility study of a distributed small reactor system has been performed in JAERI for the utilization of the heat source for public welfare, especially for air-conditioning and hot water supply, from the view point of use expansion of nuclear energy. In this report, the optimization of heat supply system including the set up and analysis of the model city are studied for the prediction of short and long term heat demand in the heat supply area. It is important process for understanding the whole system image to estimate the suitable heat source scale for the heat demand of the heat supply area, which is within a 5-km radius from heat supply source. From the analysis, it is clear that two or more set of the nuclear reactors based on 100 MW thermal power are suitable. Furthermore, it is indicated that the introduced reactor system can be utilized for more than 30 year and the heat reserve system is indispensable. This results show the feasibility of a small reactor system for district heat-and cooling supply.
Yoritsune, Tsutomu; Ishida, Toshihisa
JAERI-Tech 2003-022, 118 Pages, 2003/03
JAERI-Tech-2003-022.pdf:18.03MB
no abstracts in English
Nakano, Yoshihiro; Ishikawa, Nobuyuki; Nakatsuka, Toru; Iwamura, Takamichi
JAERI-Conf 2002-012, 219 Pages, 2002/12
JAERI-Conf-2002-012.pdf:17.4MB
no abstracts in English
Yoritsune, Tsutomu; Ishida, Toshihisa; Imayoshi, Sho*
Journal of Nuclear Science and Technology, 39(8), p.913 - 922, 2002/08
Times Cited Count：4 Percentile：28.58(Nuclear Science & Technology)no abstracts in English
Kobe, Mitsuru*; Tsunoda, Hirokazu*; Mishima, Kaichiro*; Kawasaki, Akira*; Iwamura, Takamichi
Genshiryoku eye, 48(1), p.23 - 28, 2002/01
no abstracts in English
Kawamura, Yoshinori; Konishi, Satoshi; Nishi, Masataka
Fusion Engineering and Design, 58-59, p.389 - 394, 2001/11
Times Cited Count：26 Percentile：84.46(Nuclear Science & Technology)no abstracts in English
