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Yamamoto, Kazami; Kinsho, Michikazu; Hayashi, Naoki; Saha, P. K.; Tamura, Fumihiko; Yamamoto, Masanobu; Tani, Norio; Takayanagi, Tomohiro; Kamiya, Junichiro; Shobuda, Yoshihiro; et al.
Journal of Nuclear Science and Technology, 59(9), p.1174 - 1205, 2022/09
Times Cited Count：6 Percentile：84.97(Nuclear Science & Technology)In the Japan Proton Accelerator Research Complex, the purpose of the 3 GeV rapid cycling synchrotron (RCS) is to accelerate a 1 MW, high-intensity proton beam. To achieve beam operation at a repetition rate of 25 Hz at high intensities, the RCS was elaborately designed. After starting the RCS operation, we carefully verified the validity of its design and made certain improvements to establish a reliable operation at higher power as possible. Consequently, we demonstrated beam operation at a high power, namely, 1 MW. We then summarized the design, actual performance, and improvements of the RCS to achieve a 1 MW beam.
Cs activity concentration in the aquatic insect 
(Tricoptera: Stenopsychidae) in the Ota River, Fukushima, JapanIshii, Yumiko*; Miura, Hikaru*; Jo, J.*; Tsuji, Hideki*; Saito, Rie; Koarai, Kazuma; Hagiwara, Hiroki; Urushidate, Tadayuki*; Nishikiori, Tatsuhiro*; Wada, Toshihiro*; et al.
PLOS ONE (Internet), 17(5), p.e0268629_1 - e0268629_17, 2022/05
Times Cited Count：3 Percentile：43.07(Multidisciplinary Sciences)We investigated the variability in Cs activity concentration in individual aquatic insects in detritivorous caddisfly () and carnivorous dobsonfly (
) larvae from the Ota River, Fukushima. Caddisfly larvae showed sporadically higher radioactivity, whereas no such outliers were observed in dobsonfly larvae. Autoradiography and scanning electron microscopy analyses confirmed that these caddisfly larvae samples contained radiocesium-bearing microparticles (CsMPs), which are insoluble Cs-bearing silicate glass particles. CsMPs were also found in potential food sources of caddisfly larvae, such as periphyton and drifting particulate organic matter, indicating that larvae may ingest CsMPs along with food particles of similar size. Although CsMPs distribution and uptake by organisms in freshwater ecosystems is relatively unknown, our study demonstrates that CsMPs can be taken up by aquatic insects.
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.
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.
Kubota, Ryuzaburo; Koyama, Kazuya*; Moriwaki, Hiroyuki*; Yamada, Yumi*; Shimakawa, Yoshio*; Suzuki, Toru; Kawada, Kenichi; Kubo, Shigenobu; Yamano, Hidemasa
Proceedings of 2017 International Congress on Advances in Nuclear Power Plants (ICAPP 2017) (CD-ROM), 10 Pages, 2017/04
This paper describes an analysis study on the initiating phase of the ATWS events with SAS4A in order to confirm the appropriateness of the core design for the medium-scale SFR (750MWe-1765MWt). Not using a conventional lumping method that multiple fuel sub-assemblies having a similar characteristic were assigned to one channel (representing fuel assembly in SAS4A), each channel represents only the sub-assemblies of identical operating condition. In addition, the detailed power and reactivity distribution were set reflecting the change of insertion position of control rods. Applying these detailed analysis conditions, the SAS4A analyses were performed for unprotected loss-of-flow (ULOF) and unprotected transient overpower (UTOP) during both of the nominal power and the partial power operation. As a result, more proper event progression including incoherency of events especially fuel dispersion after fuel failure was successfully evaluated and then this analysis study suggested that the power excursion with prompt criticality leading to large mechanical energy release can be prevented in the initiating phase of the current design.
Ueda, Yoshio*; Oya, Kaoru*; Ashikawa, Naoko*; Ito, Atsushi*; Ono, Tadayoshi*; Kato, Daiji*; Kawashima, Hisato; Kawamura, Gakushi*; Kenmotsu, Takahiro*; Saito, Seiki*; et al.
Purazuma, Kaku Yugo Gakkai-Shi, 88(9), p.484 - 502, 2012/09
no abstracts in English
Fukumoto, Masakatsu; Nakano, Tomohide; Itami, Kiyoshi; Wada, Takaaki*; Ueda, Yoshio*; Tanabe, Tetsuo*
Journal of Nuclear Materials, 415(Suppl.1), p.S705 - S708, 2011/08
Times Cited Count：5 Percentile：38.65(Materials Science, Multidisciplinary)Tungsten coating on the first wall in ITER is proposed to reduce in-vessel tritium retention. However, it is possibility that carbon based materials would be used at high heat load components such as limiter. To predict the tritium retention in tungsten coating, it is essential to investigate the effects of carbon impurity on deuterium retention in tungsten coating. In this study, effects of carbon impurity on deuterium retention in the tungsten coating exposed to JT-60U divertor plasmas were investigated. Deuterium was trapped by carbon which was implanted and accumulated in the tungsten coating during the plasma discharge. D/C ration of 0.04-0.08 in the tungsten coating was reached to 1/2-1/4 compared to T/C ration in carbon co-deposition layer. Therefore, simultaneous use of carbon armor materials and tungsten coating would enhance tritium retention in tungsten coating.
Umeda, Koji; Oi, Takao; Osawa, Hideaki; Oyama, Takuya; Oda, Chie; Kamei, Gento; Kuji, Masayoshi*; Kurosawa, Hideki; Kobayashi, Yasushi; Sasaki, Yasuo; et al.
JAEA-Review 2007-050, 82 Pages, 2007/12
JAEA-Review-2007-050.pdf:28.56MB
This report shows the annual report which shows the summarized results and topic outline of each project on geological disposal technology in the fiscal year of 2006.
Nishitani, Tomohiro; Nakanishi, Tsutomu*; Yamamoto, Masahiro*; Okumi, Shoji*; Furuta, Fumio*; Miyamoto, Masaharu*; Kuwahara, Makoto*; Yamamoto, Naoto*; Naniwa, Kenichi*; Watanabe, Osamu*; et al.
Journal of Applied Physics, 97(9), p.094907_1 - 094907_6, 2005/05
Times Cited Count：64 Percentile：87.31(Physics, Applied)no abstracts in English
Matsukado, Koji*; Esirkepov, T. Z.; Kinoshita, Kenichi*; Daido, Hiroyuki; Utsumi, Takayuki*; Li, Z.*; Fukumi, Atsushi*; Hayashi, Yukio; Orimo, Satoshi; Nishiuchi, Mamiko; et al.
Physical Review Letters, 91(21), p.215001_1 - 215001_4, 2003/11
Times Cited Count：136 Percentile：95.25(Physics, Multidisciplinary)no abstracts in English
Yutani, Toshiaki*; Wada, Takashi*; Matsuzuka, Ryuji*; Yamanaka,Tsuneyasu*; Watari, Yoshio*
PNC TJ9124 87-007, 43 Pages, 1987/09
To evaluate the corrosion resistance due to fuel-cladding chemical interaction (FCCI), corrosion tests of an advanced austenitic stainless steel of French manufacture and modified SUS316 stainless steel fabricated by air melting method and doble vacuum melting method with CsOH-CsI mixture, tellurium and iodine were conducted at 700C for 100 hours. The result were summarized as follows. (1)The CsOH-CsI mixture (CsOH-CsI=1) produced intergranular attack, (2)Tellurium and iodine produced matrix attack. (3)There were little difference in corrosion morphology between three alloys. (4)Advanced austenitic stainless steel and modified SUS316 stainless steel farbricated by air melting method had almost same corrosion resistances to CsOH-CsI mixtures and iodine as modified SUS316 stainless steel farbricated by double vacuum melting method.
Wada, Seiichi; Kobayashi, Yasuhiko; Funayama, Tomoo; Sakashita, Tetsuya; Yokota, Yuichiro; Matsumoto, Yoshihisa*; Oto, Takayo*; Hosoi, Yoshio*; Suzuki, Norio*; Hamada, Nobuyuki*; et al.
no journal, ,
Clustered DNA damages induced by high LET heavy ions are thought non-repairable or difficult to repair. However, much less is known about the reparability of clustered DNA damages. The major DNA repair pathway in mammalian cells is non-homologous end joining (NHEJ). In this study we investigated NHEJ pathway by exposure to high LET heavy ions, by analyzing responses of Ku to DNA damage induced by high LET heavy ions. pGFP and pGFP-Ku80 were transfected into xrs-5 cells (mutated in Ku80). Cells were irradiated with 
rays and ion beams (LET=2.7-1610 keV/
m) at TIARA JAERI-Takasaki. Survival rates were measured by colony formation assay. To examine DNA damage and NHEJ pathway induced by heavy ion beams, H2AX and GFP signal on the nuclei were observed. Xrs5-GFP-Ku80 cells were radioresistant to rays and all ion beams, in comparison with xrs5-GFP cells. When the inactivation cross section was calculated to evaluate lethal effects per one particle, the difference of inactivation cross section between xrs5-GFP cells and xrs5-GFP-Ku80 cells became smaller with increasing LET. GFP and H2AX foci on the nuclei co-localized from 10 to 30 min after C (108 keV/m) and Ne ion (321 keV/m) irradiation. While GFP foci were observed for 10 min after Ar ion (1610 keV/m) irradiation, were not observed for 20 min. The difference of LET of ion beams influenced NHEJ responses.
Wada, Seiichi; Funayama, Tomoo; Matsumoto, Yoshihisa*; Oto, Takayo*; Sakashita, Tetsuya; Hamada, Nobuyuki*; Yokota, Yuichiro; Kakizaki, Takehiko; Hosono, Yoshio*; Suzuki, Norio*; et al.
no journal, ,
no abstracts in English
Wada, Seiichi*; Funayama, Tomoo; Matsumoto, Yoshihisa*; Oto, Takayo*; Sakashita, Tetsuya; Hamada, Nobuyuki*; Kakizaki, Takehiko; Hosoi, Yoshio*; Suzuki, Norio*; Kobayashi, Yasuhiko
no journal, ,
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Wada, Seiichi*; Matsumoto, Yoshihisa*; Oto, Takayo*; Hamada, Nobuyuki*; Hara, Takamitsu*; Funayama, Tomoo; Sakashita, Tetsuya; Fukamoto, Kana; Kakizaki, Takehiko; Suzuki, Michiyo; et al.
no journal, ,
no abstracts in English
Fukumoto, Masakatsu; Nakano, Tomohide; Itami, Kiyoshi; Wada, Takaaki*; Ueda, Yoshio*; Tanabe, Tetsuo*
no journal, ,
no abstracts in English
Fukumoto, Masakatsu; Nakano, Tomohide; Itami, Kiyoshi; Wada, Takaaki*; Ueda, Yoshio*; Tanabe, Tetsuo*
no journal, ,
no abstracts in English
Fukumoto, Masakatsu; Nakano, Tomohide; Itami, Kiyoshi; Wada, Takaaki*; Ueda, Yoshio*; Tanabe, Tetsuo*
no journal, ,
no abstracts in English
Fukumoto, Masakatsu; Nakano, Tomohide; Itami, Kiyoshi; Wada, Takaaki*; Ueda, Yoshio*; Tanabe, Tetsuo*
no journal, ,
no abstracts in English
Fukumoto, Masakatsu; Nakano, Tomohide; Itami, Kiyoshi; Wada, Takaaki*; Ueda, Yoshio*; Tanabe, Tetsuo*
no journal, ,
no abstracts in English
