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Nishino, Saki; Okada, Jumpei; Watanabe, Kazuki; Furuuchi, Yuta; Yokota, Satoru; Yada, Yuji; Kusaka, Shota; Morokado, Shiori; Nakamura, Yoshinobu
JAEA-Technology 2023-011, 39 Pages, 2023/06
JAEA-Technology-2023-011.pdf:2.51MB
Tokai Reprocessing Plant (TRP) which shifted to decommissioning phase in 2014 had nuclear fuel materials such as the spent fuel sheared powder, the diluted plutonium solution and the uranium solution in a part of the reprocessing main equipment because TRP intended to resume reprocessing operations when it suspended the operations in 2007. Therefore, we have planned to remove these nuclear materials in sequence as Flush-out before beginning the decommissioning, and conducted removal of the spent fuel sheared powder as the first stage. The spent fuel sheared powder that had accumulated in the cell of the Main Plant (MP) as a result of the spent fuel shearing process was recovered from the cell floor, the shearing machine and the distributor between April 2016 and April 2017 as part of maintenance. Removing the recovered spent fuel sheared powder was conducted between June 2022 and September 2022. In this work, the recovered powder was dissolved in nitric acid at the dissolver in a small amount in order to remove it safely and early, and the dissolved solution was sent to the highly radioactive waste storage tanks without separating uranium and plutonium. Then, the dissolved solution transfer route was rinsed with nitric acid and water. Although about 15 years had passed since previous process operations, the removing work was successfully completed without any equipment failure because of the organization of a system that combines veterans experienced the operation with young workers, careful equipment inspections, and worker education and training. Removing this powder was conducted after revising the decommissioning project and obtaining approval from the Nuclear Regulation Authority owing to operating a part of process equipment.
Katabuchi, Tatsuya*; Iwamoto, Osamu; Hori, Junichi*; Kimura, Atsushi; Iwamoto, Nobuyuki; Nakamura, Shoji; Rovira Leveroni, G.; Endo, Shunsuke; Shibahara, Yuji*; Terada, Kazushi*; et al.
EPJ Web of Conferences, 281, p.00014_1 - 00014_4, 2023/03
NpRovira Leveroni, G.; Katabuchi, Tatsuya*; Tosaka, Kenichi*; Matsuura, Shota*; Kodama, Yu*; Nakano, Hideto*; Iwamoto, Osamu; Kimura, Atsushi; Nakamura, Shoji; Iwamoto, Nobuyuki
Journal of Nuclear Science and Technology, 59(1), p.110 - 122, 2022/01
Times Cited Count：5 Percentile：54.24(Nuclear Science & 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：51 Percentile：96.49(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.
Katabuchi, Tatsuya*; Iwamoto, Osamu; Hori, Junichi*; Kimura, Atsushi; Iwamoto, Nobuyuki; Nakamura, Shoji; Shibahara, Yuji*; Terada, Kazushi*; Rovira, G.*; Matsuura, Shota*
EPJ Web of Conferences, 239, p.01044_1 - 01044_4, 2020/09
Times Cited Count：2 Percentile：82.33(Nuclear Science & Technology)Onuki, Yoshichika*; Kakihana, Masashi*; Iha, Wataru*; Nakaima, Kenri*; Aoki, Dai*; Nakamura, Ai*; Honda, Fuminori*; Nakashima, Miho*; Amako, Yasushi*; Gochi, Jun*; et al.
JPS Conference Proceedings (Internet), 29, p.012001_1 - 012001_9, 2020/02
Si
without local inversion symmetryNakamura, Shota*; Hyodo, Kazushi*; Matsumoto, Yuji*; Haga, Yoshinori; Sato, Hitoshi*; Ueda, Shigenori*; Mimura, Kojiro*; Saiki, Katsuyoshi*; Iso, Kosei*; Yamashita, Minoru*; et al.
Journal of the Physical Society of Japan, 89(2), p.024705_1 - 024705_5, 2020/02
Times Cited Count：2 Percentile：19.17(Physics, Multidisciplinary)NpRovira, G.*; Katabuchi, Tatsuya*; Tosaka, Kenichi*; Matsuura, Shota*; Terada, Kazushi*; Iwamoto, Osamu; Kimura, Atsushi; Nakamura, Shoji; Iwamoto, Nobuyuki; Segawa, Mariko; et al.
Journal of Nuclear Science and Technology, 57(1), p.24 - 39, 2020/01
Times Cited Count：12 Percentile：78.39(Nuclear Science & Technology)Nakamura, Shota*; Sakakibara, Toshiro*; Shimizu, Yusei*; Kittaka, Shunichiro*; Kono, Yohei*; Haga, Yoshinori; Pospisil, J.; Yamamoto, Etsuji
Progress in Nuclear Science and Technology (Internet), 5, p.123 - 127, 2018/11
NpRovira, G.*; Katabuchi, Tatsuya*; Tosaka, Kenichi*; Matsuura, Shota*; Iwamoto, Osamu; Kimura, Atsushi; Nakamura, Shoji; Iwamoto, Nobuyuki; Terada, Kazushi*
no journal, ,
Katabuchi, Tatsuya*; Iwamoto, Osamu; Hori, Junichi*; Iwamoto, Nobuyuki; Kimura, Atsushi; Nakamura, Shoji; Shibahara, Yuji*; Terada, Kazushi*; Takamiya, Koichi*; Fukutani, Satoshi*; et al.
no journal, ,
Accurate neutron capture cross sections on long-lived MA at fast region are required for developments of nuclear transmutation system. A study to improve accuracy of the fast neutron capture cross sections has been started as a collaborative project among Tokyo Institute of Technology, Japan Atomic Energy Agency and Kyoto University since 2017. This talk reports about the background, the object and the total plan of the project as the first one of the series presentations.
