Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Suzuki, Shotaro*; Amano, Yosuke*; Enomoto, Masahiro*; Matsumoto, Akira*; Morioka, Yoshiaki*; Sakuma, Kazuyuki; Tsuruta, Tadahiko; Kaeriyama, Hideki*; Miura, Hikaru*; Tsumune, Daisuke*; et al.
Science of the Total Environment, 831, p.154670_1 - 154670_15, 2022/07
Times Cited Count:2 Percentile:29.93(Environmental Sciences)Li, Y.; Katsumata, Genshichiro*; Masaki, Koichi; Hayashi, Shotaro*; Itabashi, Yu*; Nagai, Masaki*; Suzuki, Masahide*; Kanto, Yasuhiro*
Journal of Pressure Vessel Technology, 143(4), p.041501_1 - 041501_8, 2021/08
Times Cited Count:2 Percentile:20.79(Engineering, Mechanical)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.
Yokozuka, Yuta; Sunaoshi, Mizuho*; Fujikura, Toshiki; Suzuki, Shota; Muraguchi, Yoshinori; Handa, Yuichi; Mimura, Ryuji; Terunuma, Akihiro
JAEA-Technology 2020-017, 56 Pages, 2021/01
JAEA has dismantled equipment and instrument in the JAERI's Reprocessing Test Facility (JRTF) since 1996 as a part of its decommissioning. Starting in JFY 2007, in the annex building B which stored liquid waste generated in wet reprocessing tests, the liquid waste storage tank LV-1 installed in the LV-1 room of the first basement was dismantled with the in situ dismantling method. The dismantling preparation work is described in this report. Data on manpower, radiation control, and waste in the preparation work were collected, and its work efficiency was analyzed.
Otosaka, Shigeyoshi*; Kambayashi, Shota*; Fukuda, Miho*; Tsuruta, Tadahiko; Misono, Toshiharu; Suzuki, Takashi; Aono, Tatsuo*
Environmental Science & Technology, 54(21), p.13778 - 13785, 2020/11
Times Cited Count:12 Percentile:54.1(Engineering, Environmental)Concentrations of Cs in seawater, seabed sediment, and pore water collected from the area around Fukushima were investigated from 2015 to 2018, and the potential of coastal sediments to supply radiocesium to the bottom environment was evaluated. The Cs concentration in the pore water ranged from 33 to 1934 mBq L and was 10-40 times higher than that in the overlying water (seawater overlying within 30 cm on the seabed). At most stations, the Cs concentrations in the overlying water and the pore water were approximately proportional to those in the sediment. The conditional partition coefficient between pore water and sediment was 0.9-1410 L kg, independent of the year of sampling. These results indicated that an equilibrium of Cs between pore water and sediment has established in a relatively short period, and Cs in the pore water is gradually exported to seawater near the seabed. A simple box model estimation based on these results showed that the Cs in the sediment was decreased by about 6% per year by desorption/diffusion of Cs from the seabed.
Li, Y.; Katsumata, Genshichiro*; Masaki, Koichi*; Hayashi, Shotaro*; Itabashi, Yu*; Nagai, Masaki*; Suzuki, Masahide*; Kanto, Yasuhiro*
Proceedings of 25th International Conference on Nuclear Engineering (ICONE-25) (CD-ROM), 10 Pages, 2017/07
In Japan, a PFM analysis code PASCAL (PFM Analysis of Structural Components in Aging LWR) has been developed by the Japan Atomic Energy Agency to evaluate the through-wall cracking frequencies of Japanese reactor pressure vessels (RPVs) considering neutron irradiation embrittlement and pressurized thermal shock transients. In this study, as a part of the verification activities, a working group was established in Japan, with seven organizations from industry, universities and institutes voluntarily participating as members. The source program of PASCAL was released to the members of the working group. Through one year activities, the applicability of PASCAL for structural integrity assessments of domestic RPVs was confirmed with great confidence. This paper presents the details of the verification activities of the working group including the verification plan, approaches and results.
Li, Y.; Hayashi, Shotaro*; Itabashi, Yu*; Nagai, Masaki*; Kanto, Yasuhiro*; Suzuki, Masahide*; Masaki, Koichi*
JAEA-Review 2017-005, 80 Pages, 2017/03
For the improvement of the structural integrity assessment methodology on reactor pressure vessels (RPVs), the probabilistic fracture mechanics (PFM) analysis code PASCAL has been developed and improved in JAEA based on latest knowledge. The PASCAL code evaluates the failure probabilities and frequencies of Japanese RPVs under transient events such as pressurized thermal shock considering neutron irradiation embrittlement. In order to confirm the reliability of the PASCAL as a domestic standard code and to promote the application of PFM on the domestic structural integrity assessments of RPVs, it is important to verify the probabilistic variables, functions and models incorporated in the PASCAL and summarize the verification processes and results as a document. On the basis of these backgrounds, we established a working group, composed of experts on this field besides the developers, on the verification of the PASCAL3 which is a PFM analysis module of PASCAL, and the source program of PASCAL3 was released to the members of working group. Through one year activities, the applicability of PASCAL in structural integrity assessments of domestic RPVs was confirmed with great confidence. This report summarizes the activities of the working group on the verification of PASCAL in FY2015.
Motokawa, Ryuhei; Endo, Hitoshi*; Yokoyama, Shingo*; Nishitsuji, Shotaro*; Kobayashi, Toru; Suzuki, Shinichi; Yaita, Tsuyoshi
Scientific Reports (Internet), 4, p.6585_1 - 6585_6, 2014/10
Times Cited Count:36 Percentile:70.26(Multidisciplinary Sciences)Suzuki, Hiroyuki*; Koizumi, Yasuo*; Okazaki, Shotaro*; Ito, Kei; Ohshima, Hiroyuki
no journal, ,
The occurrence of the gas entrainment (GE) phenomenon in a simple experimental system (cylindrical tank) was investigated under several conditions, i.e. liquid depth and inlet flow rate. Under GE occurrence conditions, the flow rate of the entrainment gas was measured. In addition, based on the experimental results, the mechanism of the GE occurrence was discussed.
Suzuki, Shota*; Kaneko, Akiko*; Abe, Yutaka*; Suzuki, Masahiro; Segawa, Tomoomi; Fujii, Kanichi
no journal, ,
The influences of vessel, solution and heating properties for boiling behavior were evaluated to clear them in the electro-magnetic wave (microwave) heating of the de-nitrate conversion process of nuclear fuel cycle. Boiling and fluid behavior of solution were observed by the high speed video camera, the temperature of solution level were measured by radiation thermography, and the temperature of the vessel surface was measured by thermography. The temperature of solution level was 103.2 degree, which showed that the solution was overheated. The corrected temperature on the vessel surface measured by thermography was 105.8 degree. It is expected that the inner temperature of solution is higher than that of vessel surface. It is considered that the energy of microwave concentrates at the core of solution, and flushing is leaded by generating the uniform nucleation according to overheating.
Takubo, Shota*; Agui, Akane; Liu, X.*; Suzuki, Kosuke*; Sakurai, Hiroshi*
no journal, ,
no abstracts in English
Asaoka, Hidehito; Uozumi, Yuki; Suzuki, Shota*; Yamaguchi, Kenji
no journal, ,
no abstracts in English
Agui, Akane; Sakurai, Hiroshi*; Takubo, Shota*; Suzuki, Kosuke*; Liu, X.*
no journal, ,
no abstracts in English
Agui, Akane; Sakurai, Hiroshi*; Suzuki, Kosuke*; Takubo, Shota*; Liu, X.*
no journal, ,
no abstracts in English
Agui, Akane; Sakurai, Hiroshi*; Suzuki, Kosuke*; Takubo, Shota*; Liu, X.*
no journal, ,
no abstracts in English
Motokawa, Ryuhei; Endo, Hitoshi*; Yokoyama, Shingo*; Nishitsuji, Shotaro*; Yaita, Tsuyoshi; Kobayashi, Toru; Suzuki, Shinichi
no journal, ,
no abstracts in English
Motokawa, Ryuhei; Endo, Hitoshi*; Yokoyama, Shingo*; Nishitsuji, Shotaro*; Yaita, Tsuyoshi; Kobayashi, Toru; Suzuki, Shinichi
no journal, ,
no abstracts in English
Suzuki, Shota; Asaoka, Hidehito; Uozumi, Yuki; Yamaguchi, Kenji
no journal, ,
no abstracts in English
Suzuki, Shota; Asaoka, Hidehito; Uozumi, Yuki; Yamaguchi, Kenji
no journal, ,
no abstracts in English
Suzuki, Shota; Asaoka, Hidehito; Uozumi, Yuki; Kondo, Keietsu; Yamaguchi, Kenji
no journal, ,
no abstracts in English