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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.
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：44 Percentile：97.1(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.
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：262 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.
Jo, Takahisa; Goto, Takehiro; Yabuki, Kentaro; Ikegami, Kazunori; Miyagawa, Takayuki; Mori, Tetsuya; Kubo, Atsuhiko; Kitano, Akihiro; Nakagawa, Hiroki; Kawamura, Yoshiaki; et al.
JAEA-Technology 2010-052, 84 Pages, 2011/03
JAEA-Technology-2010-052.pdf:17.14MB
The prototype fast breeder reactor MONJU resumed the System Startup Test (SST) on May 6th 2010 after five months and fourteen years shutdown since the sodium leakage of the secondary heat transport system on December 1995. Core Confirmation Test (CCT) is the first step of SST, which consists of three steps. CCT was finished on July 22nd after 78 days tests. CCT is composed 20 test items including control rods' worth evaluation, radiation dose measurement etc..
have an anomalous endohedral structure? Synthesis and single crystal X-ray structure of the carbene adductAkasaka, Takeshi*; Kono, Takayoshi*; Takematsu, Yuji*; Nikawa, Hidefumi*; Nakahodo, Tsukasa*; Wakahara, Takatsugu*; Ishitsuka, Midori*; Tsuchiya, Takahiro*; Maeda, Yutaka*; Liu, M. T. H.*; et al.
Journal of the American Chemical Society, 130(39), p.12840 - 12841, 2008/10
Times Cited Count：76 Percentile：84.38(Chemistry, Multidisciplinary)We report here the results on single crystal X-ray crystallographic analysis of the Gd@C carbene adduct (Gd@C(ad), Ad=adamantylidene). The Gd atom in Gd@C(Ad) is located at an off-centered position near a hexagonal ring in the C2v-C cage, as found for M@C (M = Sc and La) and La@C(Ad). Theoretical calculation also confirms the position of the Gd atom in the X-ray crystal structure.
Yamada, Yoshikazu; Kurita, Ichiro; Suzuki, Kazunori; Shinada, Kenta; Kato, Mitsuaki*
Proceedings of International Conference on Nuclear Energy System for Future Generation and Global Sustainability (GLOBAL 2005) (CD-ROM), 5 Pages, 2005/10
None
Shiotani, Hiroki; Ohtaki, Akira; Ono, Kiyoshi; Hirao, Kazunori; Kato, Atsushi; Yasumatsu, Naoto*; Kubota, Sadae*
JNC TN9400 2004-052, 514 Pages, 2004/09
JNC-TN9400-2004-052.pdf:8.85MB
This report presents the outline of the development and the results of characteristic evaluation on the candidate Fast Reactor (FR) cycle system concepts, scenario study on FR cycle deployment and cost-benefit analysis on the candidate FR cycle system concepts in the interim evaluation (FY2001 through FY2003) of the second phase of the Japanese "Feasibility Study on Commercialization of Fast Breeder Reactor Cycle System (FS)".
Nakagiri, Toshio; Kato, Kazunori*; Miyahara, Shinya
JNC TN9400 2003-069, 181 Pages, 2003/07
JNC-TN9400-2003-069.pdf:3.96MB
Experiments were carried out to study the release behavior of iodine and cesium with sodium and their mixed aerosol behabior during sodium pool combustion. The experimental results were compared with calculated results by computer codes (SPM code and ABC-INTG code). The following results were obtained from this study.(1) The measured release rates of sodium, cesium and iodine release rate during sodium combustion increased with sodium temperature rise. The calculated release rates by the SPM code did not depend on sodium pool temperature clearly as measured values.(2) Retention factors of cesium and iodine to sodium pool during sodium combustion were larger than those in equilibrium evaporation.(3) Mass concentration of cesium and iodine in sodium aerosol were nearly constant, and it was confirmed that sodium-volatile FPs mixed aerosol can be treated as single component aerosol.(4) The generation of gaseous iodine was not confirmed in this experimental series. However, the possibility of gaseous iodine generation was indicated by thermodynamical analysis, and it was found that past test results were qualitatively explained.
Futagami, Satoshi; Ohno, Shuji; Kato, Kazunori*
JNC TN9400 2003-067, 168 Pages, 2003/06
JNC-TN9400-2003-067.pdf:13.7MB
Since 1998, the test (Run-F7 series) was performed to acquire the fundamental knowledge about the sodium pool growth and floor liner temperature in the case of small-scale leakage of sodium. And the test (Run-F8 series) was performed to know the floor liner material corrosion mechanism under high moisture conditions. In both test series, those influences are investigated by making the rate of sodium leakage, and moisture conditions of supply air into main parameters. As the last test, (1)Run-F7-4 (June 28, 2000) and (2)Run-F8-2 (January 26, 2000) were carried out. The conclusion of the following which receives sodium small-scale leakage (about 10 kg/h) was obtained from these experiments and the result of old Run-F7 and Run-F8 series. - The peak temperature of a catch pan tends to become lower with decrease of sodium leak rate. Moreover, height of leak point and moisture conditions also become the factor which raises the catch pan peak temperature. - Although it grows up in proportion [almost] to time in early stages of leakage about growth of a sodium pool, growth stops during the leakage. Moreover, the final growth area is mostly proportional to the rate of sodium leakage. - It was suggested by the measured value of catch pan corrosion thickness and a material analysis result that the dominant corrosion mechanism was relatively slow `Na-Fe double oxidization type corrosion` even under the high moisture condition of 4.6 to 4.8%. And the chemical analysis result of a deposit also suggested that the catch pan material was in the environment in which `molten salt type corrosion` was not easy to occur.
Ojima, Hisao; Torata, Shinichiro; Nomura, Kazunori; Kato, Hiroshi
Proceedings of 2nd International Workshop on Nuclear Fuel Cycle; Nuclear Fuel Cycle from the Viewpoint of Disposal Site Utilization, p.34 - 35, 2003/00
None
Akasaka, Takeshi*; Kato, Tatsuhisa*; Kobayashi, Kaoru*; Nagase, Shigeru*; Yamamoto, Kazunori; Funasaka, Hideyuki; Takahashi, Takeshi
Nature, 374, p.600 - 601, 1994/04
Times Cited Count：156 Percentile：99.11(Multidisciplinary Sciences)no abstracts in English
Kato, Masato; Sakurai, Koji*; Kano, Yoshiharu*; Funasaka, Hideyuki; Yamamoto, Kazunori; *; Wada, Yukio
PNC TN8410 92-060, 7 Pages, 1992/03
None
Irisawa, Eriko; Suzuki, Kazunori*; Kumagai, Mikio*; Kato, Chiaki; Ueno, Fumiyoshi; Abe, Hitoshi
no journal, ,
For the corrosion of stainless steels in the nitric acid solution containing oxidizing metallic ions, it is important factor that the relation between re-oxidation of metallic ions which is reduced with the corrosion reaction and the redox reaction of nitric acid. To make clear the effect of nitrogen oxides formed from nitric acid on oxidation behavior of tetravalent vanadium, changing of concentrations of nitrogen oxide discharged to gas phase from solution and nitrous acid in solution during oxidation reaction of vanadium were measured. The results showed that the nitrogen dioxide acted as oxidant on the oxidation reaction of vanadium.
Takir, D.*; Kitazato, Kohei*; Milliken, R. E.*; Iwata, Takahiro*; Abe, Masanao*; Otake, Makiko*; Matsuura, Shuji*; Arai, Takehiko*; Nakauchi, Yusuke*; Nakamura, Tomoki*; et al.
no journal, ,
JAXA spacecraft and sample return mission Hayabusa2 has arrived at the near-Earth asteroid 162173 Ryugu, which is classified a primitive carbonaceous object. Here we report recent results of near-infrared spectrometer (NIRS3) on the Hayabusa2 spacecraft. The observations provide direct measurements of the surface composition of Ryugu and context for the returned samples. NIRS3 has detected a weak and narrow absorption feature centered at 2.72 micrometer across entire observed surface. This absorption feature is attributed to the presence of OH-bearing minerals. The NIRS3 observations also revealed that Ryugu is the darkest object to be observed up-close by a visiting spacecraft. The intensity of the OH feature and low albedo are consistent with thermally-and/or shock-metamorphosed, and/or carbon-rich space-weathered primitive and hydrated carbonaceous chondrites.
