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Arai, Yoichi; Watanabe, So; Nakahara, Masaumi; Funakoshi, Tomomasa; Hoshino, Takanori; Takahatake, Yoko; Sakamoto, Atsushi; Aihara, Haruka; Hasegawa, Kenta; Yoshida, Toshiki; et al.
Progress in Nuclear Science and Technology (Internet), 7, p.168 - 174, 2025/05
The Japan Atomic Energy Agency (JAEA) has been conducting a project named "Systematic Treatment of RAdioactive liquid waste for Decommissioning (STRAD)" project since 2018 for fundamental and practical studies for treating radioactive liquid wastes with complicated compositions. Fundamental studies have been conducted using genuine liquid wastes accumulated in a hot laboratory of the JAEA called the Chemical Processing Facility (CPF), and treatment procedures for all liquid wastes in CPF were successfully designed on the results obtained. As the next phase of the project, new fundamental and practical studies on primarily organic liquid wastes accumulated in different facilities of JAEA are in progress. This paper reviews the representative achievements of the STRAD project and introduces an overview of ongoing studies.
Sakamoto, Masahiro; Okumura, Keisuke; Kanno, Ikuo; Matsumura, Taichi; Terashima, Kenichi; Riyana, E. S.; Mizokami, Masato*; Mizokami, Shinya*
JAEA-Research 2024-017, 14 Pages, 2025/03
In the TEPCO's Fukushima Daiichi Nuclear Power Station (1F), a trial retrieval of fuel debris with small-amount from Unit 2 is planned. The retrieved fuel debris will be transported out of 1F to Institutes in Ibaraki prefecture for analysis. The analyzed results will be utilized for the improvement of the processes (retrieval, transportation and storage) in the fuel debris management as feedback, and also for the development of technologies necessary in the future. The weight of fuel debris in the trial retrieval is planned to be a few grams. After the trial, the scale of retrieval will be expanded step by step. In the trial retrieval, a rational transportation container should be considered beforehand, according to the laws and regulations associated with the off-site transportation. The transportation container has a classification and the classification is decided according to the radioactivity of the material in the container. In this report, we evaluated the applicability of the Type A transport container to contribute to the safety assessment of retrieved fuel debris.
Sakamoto, Masahiro; Okumura, Keisuke; Kanno, Ikuo; Matsumura, Taichi; Terashima, Kenichi; Riyana, E. S.; Kaneko, Junichi*; Mizokami, Masato*; Mizokami, Shinya*
Journal of Nuclear Science and Technology, 10 Pages, 2025/00
Times Cited Count:0 Percentile:0.00(Nuclear Science & Technology)Emura, Yuki; Takai, Toshihide; Kikuchi, Shin; Kamiyama, Kenji; Yamano, Hidemasa; Yokoyama, Hiroki*; Sakamoto, Kan*
Journal of Nuclear Science and Technology, 61(7), p.911 - 920, 2024/07
Times Cited Count:0 Percentile:0.00(Nuclear Science & Technology)Riyana, E. S.; Okumura, Keisuke; Sakamoto, Masahiro; Matsumura, Taichi; Terashima, Kenichi; Kanno, Ikuo
Journal of Nuclear Science and Technology, 61(2), p.269 - 276, 2024/02
Times Cited Count:0 Percentile:0.00(Nuclear Science & Technology)Koyama, Shinichi; Ikeuchi, Hirotomo; Mitsugi, Takeshi; Maeda, Koji; Sasaki, Shinji; Onishi, Takashi; Tsai, T.-H.; Takano, Masahide; Fukaya, Hiroyuki; Nakamura, Satoshi; et al.
Hairo, Osensui, Shorisui Taisaku Jigyo Jimukyoku Homu Peji (Internet), 216 Pages, 2023/11
In FY 2021 and 2022, JAEA perfomed the subsidy program for "the Project of Decommissioning and Contaminated Water Management (Development of Analysis and Estimation Technology for Characterization of Fuel Debris (Development of Technologies for Enhanced Analysis Accuracy, Thermal Bahavior Estimation, and Simplified Analysis of Fuel Debris)" started in FY 2021. This presentation material summarized the results of the project, which will be available shortly on the website of Management Office for the Project of Decommissioning, Contaminated Water and Treated Water Management.
Sakamoto, Kan*; Adachi, Mika*; Tokushima, Kazuyuki*; Aomi, Masaki*; Shibata, Hiroki; Nagae, Yuji; Kurata, Masaki
Zirconium in the Nuclear Industry; 20th International Symposium (ASTM STP 1645), p.411 - 432, 2023/11
Ukai, Shigeharu; Sakamoto, Kan*; Otsuka, Satoshi; Yamashita, Shinichiro; Kimura, Akihiko*
Journal of Nuclear Materials, 583, p.154508_1 - 154508_24, 2023/09
Times Cited Count:32 Percentile:95.63(Materials Science, Multidisciplinary)Nakanishi, Takumi*; Hori, Yuta*; Shigeta, Yasuteru*; Sato, Hiroyasu*; Kiyanagi, Ryoji; Munakata, Koji*; Ohara, Takashi; Okazawa, Atsushi*; Shimada, Rintaro*; Sakamoto, Akira*; et al.
Journal of the American Chemical Society, 145(35), p.19177 - 19181, 2023/08
Times Cited Count:5 Percentile:49.39(Chemistry, Multidisciplinary)Sawada, Atsushi; Sakamoto, Kazuhiko*; Watahiki, Takanori*; Imai, Hisashi*
SKB P-17-06, 154 Pages, 2023/08
Kawasaki, Takuro; Fukuda, Tatsuo; Yamanaka, Satoru*; Sakamoto, Tomokazu*; Murayama, Ichiro*; Kato, Takanori*; Baba, Masaaki*; Hashimoto, Hideki*; Harjo, S.; Aizawa, Kazuya; et al.
Journal of Applied Physics, 131(13), p.134103_1 - 134103_7, 2022/04
Times Cited Count:2 Percentile:15.59(Physics, Applied)Kikuchi, Shin; Takai, Toshihide; Yamano, Hidemasa; Sakamoto, Kan*
Proceedings of 28th International Conference on Nuclear Engineering (ICONE 28) (Internet), 9 Pages, 2021/08
In a postulated severe accidental condition of sodium-cooled fast reactor (SFR), eutectic melting between boron carbide (BC) and stainless steel (SS) may occur. Thus, behavior of B
C-SS eutectic melting is one of the phenomena to evaluate the core disruptive accidents in SFR. In this study, the reaction experiments using SS crucibles and the pellets of SS with low B
C concentration as samples were performed to simulate the state of the reaction interface in which the eutectic reaction and interdiffusion of B
C-SS have progressed to a certain extent. It was revealed that the rate constants of eutectic reaction between SS and SS with low B
C concentration are smaller than that of B
C-SS eutectic reaction at high temperatures.
Aghamiri, S. M. S.*; Sugawara, Naoya*; Ukai, Shigeharu; Ono, Naoko*; Sakamoto, Kan*; Yamashita, Shinichiro
Materials Characterization, 176, p.111043_1 - 111043_6, 2021/06
Advanced oxidation-resistant FeCrAl ODS alloys were developed via the control of composition-processing conditions for the accident tolerant fuel (ATF) cladding. For the first time, a single-crystal like recrystallized FeCrAl ODS alloy was achieved with a unique crystallographic texture of 110-plane and 211-direction and a high number density of fine nanoscale oxide particles. Evaluation of yield strengths at different temperatures showed higher values in transverse (T) direction than longitudinal (L) direction. The crystal orientation dependence of the yield strength up to 800C was attributed to lower value of Schmid factor in transverse direction. Accordingly, the critical resolved shear stress of this practical class of advanced materials was calculated in various temperatures.
Kikuchi, Shin; Sakamoto, Kan*; Takai, Toshihide; Yamano, Hidemasa
Nihon Kikai Gakkai 2020-Nendo Nenji Taikai Koen Rombunshu (Internet), 4 Pages, 2020/09
In a postulated severe accidental condition of sodium-cooled fast reactor (SFR), eutectic melting between boron carbide (BC) as control rod element and stainless steel (SS) as control rod cladding or related structure may occur. Thus, behavior of B
C-SS eutectic melting is one of the phenomena to evaluate the core disruptive accidents in SFR. In order to clarify the kinetic feature of B
C-SS eutectic melting process in the interface, the thinning test for SS crucibles using the pellets of B
C or SS with low B
C concentration were performed to obtain the rate constant with dependence of B
C concentration against SS. It was found that the rate constants of eutectic melting between SS and SS low B
C concentration were smaller than that of B
C-SS in the high temperature range. Besides, the rate constant of eutectic melting between SS and B
C containing SS became small when decreasing the B
C concentration against SS.
Kim, J.*; Yamanaka, Satoru*; Murayama, Ichiro*; Kato, Takanori*; Sakamoto, Tomokazu*; Kawasaki, Takuro; Fukuda, Tatsuo; Sekino, Toru*; Nakayama, Tadachika*; Takeda, Masatoshi*; et al.
Sustainable Energy & Fuels (Internet), 4(3), p.1143 - 1149, 2020/03
Times Cited Count:22 Percentile:63.45(Chemistry, Physical)Aghamiri, S. M. S.*; Sowa, Takashi*; Ukai, Shigeharu*; Ono, Naoko*; Sakamoto, Kan*; Yamashita, Shinichiro
Materials Science & Engineering A, 771, p.138636_1 - 138636_12, 2020/01
Times Cited Count:39 Percentile:88.35(Nanoscience & Nanotechnology)Oxide dispersion strengthened (ODS) FeCrAl ferritic steels are being developed as potential accident tolerance fuel cladding materials for the light water reactors (LWRs) due to significant improvement in steam oxidation by alumina forming scale and good mechanical properties up to high temperatures. In this study, the microstructural characteristics and tensile properties of the two FeCrAl ODS cladding tubes with different extrusion temperatures of 1100C and 1150
C were investigated during processing conditions. While the hot extruded sample showed micron sized elongated grains with strong
-fiber in
110
texture, cold pilger rolling process change the microstructure to submicron/micron size grain structure along with texture evolution to both
-fiber (
110
texture) and
-fiber ({111} texture) via crystalline rotations. Subsequently, final annealing resulted in evolution of microstructure to large grain recrystallized structure starting at recrystallization temperature of
810-850
C. Two distinct texture development happened in recrystallized cladding tubes, i.e., only large elongated grains of (110)
211
texture following extrusion temperature of 1100
C; and two texture components of (110)
211
and {111}
112
following higher extrusion temperature of 1150
C. The different texture development and retarding of recrystallization progress in 1100
C-extruded cladding tubes were attributed to higher distribution of oxide particles.
Ohashi, Kunihide*; Hino, Takanori*; Kobayashi, Hiroshi*; Onodera, Naoyuki; Sakamoto, Nobuaki*
Journal of Marine Science and Technology, 24(3), p.884 - 901, 2019/09
Times Cited Count:23 Percentile:79.01(Engineering, Marine)An unsteady Reynolds averaged Navier-Stokes solver with a structured overset grid method has been developed. Velocity pressure coupling is achieved using an artificial compressibility approach, spatial discretization is based on a FVM. Body motions are considered using the grid deformation technique and grid velocities in the convective term. The full multigrid (FMG) method is applied to obtain fast convergence. The cell flag on a coarse grid level is determined using the cell flag on a fine grid level. In the coarse and fine grid level calculations at the FMG stage, the data are interpolated until the finest grid level is achieved at an overset update interval. Then, the data are updated based on the overset relations at the finest grid level and then transferred to a coarser grid level. The computations for flows around a hull form, including an unsteady simulation with regular waves, are demonstrated.
Yamashita, Shinichiro; Ioka, Ikuo; Nemoto, Yoshiyuki; Kawanishi, Tomohiro; Kurata, Masaki; Kaji, Yoshiyuki; Fukahori, Tokio; Nozawa, Takashi*; Sato, Daiki*; Murakami, Nozomu*; et al.
Proceedings of International Nuclear Fuel Cycle Conference / Light Water Reactor Fuel Performance Conference (Global/Top Fuel 2019) (USB Flash Drive), p.206 - 216, 2019/09
After the nuclear accident at Fukushima Daiichi Power Plant, research and development (R&D) program for establishing technical basis of accident-tolerant fuel (ATF) started from 2015 in Japan. Since then, both experimental and analytical studies necessary for designing a new light water reactor (LWR) core with ATF candidate materials are being conducted within the Japanese ATF R&D Consortium for implementing ATF to the existing LWRs, accompanying with various technological developments required. Until now, we have accumulated experimental data of the candidate materials by out-of-pile tests, developed fuel evaluation codes to apply to the ATF candidate materials, and evaluated fuel behavior simulating operational and accidental conditions by the developed codes. In this paper, the R&D progresses of the ATF candidate materials considered in Japan are reviewed based on the information available such as proceedings of international conference and academic papers, providing an overview of ATF program in Japan.
Takano, Kazuya; Sakamoto, Yoshihiko; Morohoshi, Kyoichi*; Okazaki, Hitoshi*; Gima, Hiromichi*; Teramae, Takuma*; Ikarimoto, Iwao*; Botte, F.*; Dirat, J.-F.*; Dechelette, F.*
Proceedings of 2019 International Congress on Advances in Nuclear Power Plants (ICAPP 2019) (Internet), 8 Pages, 2019/05
ASTRID has the objective to integrate innovative options in order to prepare the 4th generation reactors. In ASTRID, large number of tubes are installed above each fuel subassembly to monitor the core. These instrumentations such as thermocouples (TC) and Failed Fuel Detection and Location (FFDL) systems are integrated into Above Core Structure (ACS) with various sizes tubes. In the present study, the routing study for TC tubes and FFDL tubes was performed with 3D modeling and mock-up experiment of the ACS designed for ASTRID with 1500 MW thermal power in order to clarify the integration process and secure the design hypotheses. Although some problems on fabricability were found in the mock-up experiment, the possible solutions were proposed. The present study gives manufacturing feedback to design team and will contribute to increase the knowledge for ACS design and fabricability.
Sakamoto, Tetsuo*; Morita, Masato*; Kanenari, Keita*; Tomita, Hideki*; Sonnenschein, V.*; Saito, Kosuke*; Ohashi, Masaya*; Kato, Kotaro*; Iguchi, Tetsuo*; Kawai, Toshihide*; et al.
Analytical Sciences, 34(11), p.1265 - 1270, 2018/11
Times Cited Count:10 Percentile:33.86(Chemistry, Analytical)