Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Li, X.; Yamaji, Akifumi*; Sato, Ikken*; Yamashita, Takuya
Annals of Nuclear Energy, 214, p.111217_1 - 111217_13, 2025/05
Times Cited Count:0 Percentile:0.00(Nuclear Science & Technology)Sato, Ikken; Yoshikawa, Shinji; Yamashita, Takuya; Shimomura, Kenta; Cibula, M.*; Mizokami, Shinya*
Nuclear Engineering and Design, 422, p.113088_1 - 113088_24, 2024/06
Times Cited Count:0 Percentile:0.00(Nuclear Science & Technology)Li, X.; Yamaji, Akifumi*; Sato, Ikken*; Yamashita, Takuya; Nagae, Yuji
Proceedings of 11th European Review Meeting on Severe Accident Research Conference (ERMSAR 2024) (Internet), 12 Pages, 2024/05
Sato, Ikken; Yoshikawa, Shinji; Yamashita, Takuya; Shimomura, Kenta; Cibula, M.*; Mizokami, Shinya*
Nuclear Engineering and Design, 414, p.112574_1 - 112574_20, 2023/12
Tsuchikawa, Yusuke; Kai, Tetsuya; Abe, Yuta; Oikawa, Kenichi; Parker, J. D.*; Shinohara, Takenao; Sato, Ikken
Journal of Physics; Conference Series, 2605, p.012022_1 - 012022_6, 2023/10
We developed a method to obtain the areal density distribution of boron, which has a large neutron cross section, by means of an energy resolved neutron imaging. Commonly in a measurement of elements with very high neutron sensitivity, the quantitative measurement becomes more difficult with the amount of element due to the neutron self-shielding effect. To avoid this effect, an energy-resolved method using known cross section data was attempted, and a quantitative imaging of such elements was demonstrated at the MLF of J-PARC. This presentation introduces a measurement of melted simulated-fuel assemblies obtained in the research of the Fukushima Daiichi Nuclear Power Plant after the severe accident. Energy-dependent neutron transmission rates of the samples were measured by a neutron imaging detector, and were analyzed to obtained the areal density of boron at each position.
Yamashita, Takuya; Honda, Takeshi*; Mizokami, Masato*; Nozaki, Kenichiro*; Suzuki, Hiroyuki*; Pellegrini, M.*; Sakai, Takeshi*; Sato, Ikken; Mizokami, Shinya*
Nuclear Technology, 209(6), p.902 - 927, 2023/06
Times Cited Count:5 Percentile:82.11(Nuclear Science & Technology)Sato, Ikken; Yoshikawa, Shinji; Yamashita, Takuya; Cibula, M.*; Mizokami, Shinya*
Nuclear Engineering and Design, 404, p.112205_1 - 112205_21, 2023/04
Times Cited Count:10 Percentile:96.03(Nuclear Science & Technology)Based on updated knowledge from plant-internal investigations, experiments and model simulations until now, the in-vessel phase of Fukushima-Daiichi Nuclear Power Station Unit 2 was analyzed using the MAAP code. In Unit 2, it is considered that the core material enthalpy was relatively low when it relocated to the lower plenum of the pressure vessel, then, cooled by the coolant and solidified there. Although the MAAP code tended to underestimate the degree of core-material oxidation during the relocation, this probable underestimation was compensated for by an existing study that was considered more reliable, so that more realistic debris conditions in the lower plenum could be obtained. Basic validity of the former prediction of the Unit 2 accident progression behavior was confirmed and detailed boundary condition for the later phase was provided. This boundary condition should be utilized for future studies addressing debris reheating process leading to lower head failure and debris relocation toward the pedestal.
Madokoro, Hiroshi; Yamashita, Takuya; Gaus-Liu, X.*; Cron, T.*; Fluhrer, B.*; Sato, Ikken; Mizokami, Shinya*
Nuclear Technology, 209(2), p.144 - 168, 2023/02
Times Cited Count:2 Percentile:30.61(Nuclear Science & Technology)Yamashita, Takuya; Madokoro, Hiroshi; Sato, Ikken
Journal of Nuclear Engineering and Radiation Science, 8(2), p.021701_1 - 021701_13, 2022/04
Sato, Ikken; Yamaji, Akifumi*; Li, X.*; Madokoro, Hiroshi
Mechanical Engineering Journal (Internet), 9(2), p.21-00436_1 - 21-00436_17, 2022/04
Madokoro, Hiroshi; Yamashita, Takuya; Sato, Ikken; Gaus-Liu, X.*; Cron, T.*; Fluhrer, B.*; Stngle, R.*; Wenz, T.*; Vervoortz, M.*; Mizokami, Shinya
Proceedings of 19th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-19) (Internet), 16 Pages, 2022/03
Sato, Ikken
Nuclear Engineering and Design, 383, p.111426_1 - 111426_19, 2021/11
Times Cited Count:7 Percentile:63.20(Nuclear Science & Technology)Madokoro, Hiroshi; Sato, Ikken
Nuclear Engineering and Design, 376, p.111123_1 - 111123_15, 2021/05
Times Cited Count:12 Percentile:78.87(Nuclear Science & Technology)Sato, Ikken; Arai, Yuta*; Yoshikawa, Shinji
Journal of Nuclear Science and Technology, 58(4), p.434 - 460, 2021/04
Times Cited Count:7 Percentile:63.20(Nuclear Science & Technology)Sato, Ikken
Enerugi Rebyu, 41(4), p.17 - 19, 2021/03
The accident progression behavior leading to core melting and after the start of the core melting at Fukushima Daiichi Nuclear Power Station Unit 3 were estimated based on data analysis mainly based on plant data such as pressure and knowledge obtained from existing analysis evaluations. In Unit 3, it is estimated that it took several hours for fuel debris to fall on to the pedestal floor, and it is likely that it was cooled by liquid coolant presented on the containment floor.
Abe, Yuta; Tsuchikawa, Yusuke; Kai, Tetsuya; Matsumoto, Yoshihiro*; Parker, J. D.*; Shinohara, Takenao; Oishi, Yuji*; Kamiyama, Takashi*; Nagae, Yuji; Sato, Ikken
JPS Conference Proceedings (Internet), 33, p.011075_1 - 011075_6, 2021/03
Tsuchikawa, Yusuke; Abe, Yuta; Oishi, Yuji*; Kai, Tetsuya; Toh, Yosuke; Segawa, Mariko; Maeda, Makoto; Kimura, Atsushi; Nakamura, Shoji; Harada, Masahide; et al.
JPS Conference Proceedings (Internet), 33, p.011074_1 - 011074_6, 2021/03
In the decommissioning of the Fukushima-Daiichi (1F) Nuclear Power Plant, it is essential to understand characteristics of the melted core materials. The estimation of boride in the real debris is of great importance to develop safe debris removal plans. Hence, it is required to investigate the amount of boron in the melted core materials with nondestructive methods. Prompt gamma-ray activation analysis (PGAA) is one of the useful techniques to determine the amount of borides by means of the 478 keV prompt gamma-ray from neutron absorption reaction of boron. Moreover, it is well known that the width of the 478 keV gamma-ray peak is typically broadened due to the Doppler effect. The degree of the broadening is affected by coexisting materials, and can be recognized by the width of the prompt gamma-ray peak. As a feasibility study, the prompt gamma-ray from boride samples were measured using the ANNRI, NOBORU, and RADEN beamlines at the Materials and Life Science Experimental Facility (MLF) of Japan Proton Accelerator Complex (J-PARC).
Tsuchikawa, Yusuke; Kai, Tetsuya; Abe, Yuta; Oishi, Yuji*; Sun, Y.*; Oikawa, Kenichi; Nakatani, Takeshi; Sato, Ikken
Nuclear Instruments and Methods in Physics Research A, 991, p.164964_1 - 164964_5, 2021/03
Times Cited Count:1 Percentile:13.95(Instruments & Instrumentation)Peak shape analysis was performed for the energy spectra of Doppler-broadened prompt -rays generated by neutron capture reactions with various boride or boron samples. Significant differences were observed between nonmetallic and metallic borides. Minor differences between the peak shapes of prompt
-rays from zirconium- and ferro-borons were evaluated by a peak fitting method. The identification of zirconium- and ferro-borons and other types of borides was estimated.
Yamashita, Takuya; Sato, Ikken; Honda, Takeshi*; Nozaki, Kenichiro*; Suzuki, Hiroyuki*; Pellegrini, M.*; Sakai, Takeshi*; Mizokami, Shinya*
Nuclear Technology, 206(10), p.1517 - 1537, 2020/10
Times Cited Count:22 Percentile:91.22(Nuclear Science & Technology)Abe, Yuta; Tsuchikawa, Yusuke; Kai, Tetsuya; Matsumoto, Yoshihiro*; Parker, J. D.*; Shinohara, Takenao; Oishi, Yuji*; Kamiyama, Takashi*; Nagae, Yuji; Sato, Ikken
Proceedings of 2020 International Conference on Nuclear Engineering (ICONE 2020) (Internet), 6 Pages, 2020/08