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Onishi, Takashi; Koyama, Shinichi*; Yokoyama, Keisuke; Morishita, Kazuki; Watanabe, Masashi; Maeda, Shigetaka; Yano, Yasuhide; Oki, Shigeo
Nuclear Engineering and Design, 432, p.113755_1 - 113755_17, 2025/02
Times Cited Count:0 Percentile:0.00(Nuclear Science & Technology)Sato, Nobuaki*; Kameo, Yutaka; Sato, Soichi; Kumagai, Yuta; Sato, Tomonori; Yamamoto, Masahiro*; Watanabe, Yutaka*; Nagai, Takayuki; Niibori, Yuichi*; Watanabe, Masayuki; et al.
Introduction to Dismantling and Decommissioning Chemistry, 251 Pages, 2024/09
This book focuses on the dismantling and decommissioning of nuclear facilities and reactors that have suffered severe accidents. In Part 1, we introduce basic aspects ranging from fuel chemistry, analytical chemistry, radiation chemistry, corrosion, and decontamination chemistry to waste treatment and disposal. Then, Part 2 covers the chemistry involved in the decommissioning of various nuclear facilities, and discusses what chemical approaches are necessary and possible for the decommissioning of TEPCO's Fukushima Daiichi Nuclear Power Plants, how decommissioning should be carried out, and what kind of research and development and also human resource development are required for this.
Usui, Yoshiya*; Ueshima, Makoto*; Hase, Hideaki*; Ichihara, Hiroshi*; Aizawa, Koki*; Koyama, Takao*; Sakanaka, Shinya*; Ogawa, Tsutomu*; Yamaya, Yusuke*; Nishitani, Tadashi*; et al.
Journal of Geophysical Research; Solid Earth, 129(5), p.e2023JB028522_1 - e2023JB028522_22, 2024/05
Times Cited Count:2 Percentile:69.68(Geochemistry & Geophysics)We elucidated the crustal heterogeneities beneath a strain concentration area on the back-arc side of the northeastern Japan Arc based on electrical resistivity. By deploying magnetotelluric surveys, we revealed the three-dimensional electrical resistivity structure in the crust, suggesting the coexistence of two types of strain-concentration mechanisms in the strain-concentration area. The shallow conductive layers and lower-crustal conductors appear to act as low-elastic-modulus and low-viscosity areas, respectively, and are responsible for the strain concentration. We found a spatial correlation between the edges of the lower-crustal conductors and the epicenters of large intraplate earthquakes. Weak shear zones in the conductive lower crust may cause stress loading on faults in the brittle upper crust, resulting in large earthquakes. We also identified vertical conductors ranging from the lower crust to Quaternary volcanoes, which may indicate fluid paths to these volcanoes.
Ikeuchi, Hirotomo; Koyama, Shinichi
Nihon Genshiryoku Gakkai-Shi ATOMO, 66(2), p.74 - 78, 2024/02
For the steady removal of fuel debris from the TEPCO's Fukushima Daiichi Nuclear Power Station (1F), it is an urgent issue to establish analysis technology and systems for fuel debris samples with unknown properties (unknown samples). For this purpose, through analysis tests using samples with known properties (simulated fuel debris) and discussions among experts, the validity of analysis results and the factors that cause errors has been identified. In addition to knowing the current level of analysis accuracy, studies are being conducted to understand and improve the influencing factors. This paper introduces a part of the development of infrastructure for analysis and evaluation technology of "nuclides and element content."
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.
Yamashita, Takuya; Shimomura, Kenta; Nagae, Yuji; Yamaji, Akifumi*; Mizokami, Shinya; Mitsugi, Takeshi; Koyama, Shinichi
Hairo, Osensui, Shorisui Taisaku Jigyo Jimukyoku Homu Peji (Internet), 53 Pages, 2023/10
JAEA performed the subsidy program for the "Project of Decommissioning, Contaminated Water and Treated Water Management (Development of Analysis and Estimation Technologies for Characterization of Fuel Debris (Development of Estimation Technologies of RPV Damaged Condition, etc.) in 2022JFY. This presentation summarized briefly 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.
Kazama, Hiroyuki; Konashi, Kenji*; Suzuki, Tatsuya*; Koyama, Shinichi; Maeda, Koji; Sekio, Yoshihiro; Onishi, Takashi; Abe, Chikage*; Shikamori, Yasuyuki*; Nagai, Yasuyoshi*
Journal of Analytical Atomic Spectrometry, 38(8), p.1676 - 1681, 2023/07
Times Cited Count:4 Percentile:63.35(Chemistry, Analytical)Iwasa, Kazuaki*; Suyama, Kazuya*; Kawamura, Seiko; Nakajima, Kenji; Raymond, S.*; Steffens, P.*; Yamada, Akira*; Matsuda, Tatsuma*; Aoki, Yuji*; Kawasaki, Ikuto; et al.
Physical Review Materials (Internet), 7(1), p.014201_1 - 014201_11, 2023/01
Times Cited Count:4 Percentile:42.21(Materials Science, Multidisciplinary)Ikeuchi, Hirotomo; Koyama, Shinichi; Osaka, Masahiko; Takano, Masahide; Nakamura, Satoshi; Onozawa, Atsushi; Sasaki, Shinji; Onishi, Takashi; Maeda, Koji; Kirishima, Akira*; et al.
JAEA-Technology 2022-021, 224 Pages, 2022/10
A set of technology, including acid dissolving, has to be established for the analysis of content of elements/nuclides in the fuel debris samples. In this project, a blind test was performed for the purpose of clarifying the current level of analytical accuracy and establishing the alternative methods in case that the insoluble residue remains. Overall composition of the simulated fuel debris (homogenized powder having a specific composition) were quantitatively determined in the four analytical institutions in Japan by using their own dissolving and analytical techniques. The merit and drawback for each technique were then evaluated, based on which a tentative flow of the analyses of fuel debris was constructed.
Nakayoshi, Akira; Koyama, Shinichi; Washiya, Tadahiro
Proceedings of International Topical Workshop on Fukushima Decommissioning Research (FDR2022) (Internet), 4 Pages, 2022/10
The activity of the PreADES project was carried out under the collaboration with many international organizations, and accumulated useful expertise. Following project tasks were discussed: (1) the Characteristic table that clarified characteristics of fuel debris for 1F, TMI2, and Chernobyl from various analyses and experiments, (2) Compiling informative tables for fuel debris analysis (the Analytical table, the Major issue and methodology table; the Hot testing analysis capabilities table). The first one identified analysis data to be obtained, and the last one indicated practical appropriate and optimal methodologies for fuel debris handling, (3) future international R&D framework. Through these activities with many discussions, project partners re-realized that important aspects for the success of future collaborative initiative was to implement conditions for fluid dialogue and information exchange between involved organizations. Currently, post-PreADES project, "Fukushima Daiichi Nuclear Power Station Accident Information Collection and Evaluation (FACE)" project has been launched and discussion is ongoing enthusiastically.
Omasa, Yoshinori*; Takagi, Shigeyuki*; Toshima, Kento*; Yokoyama, Kaito*; Endo, Wataru*; Orimo, Shinichi*; Saito, Hiroyuki*; Yamada, Takeshi*; Kawakita, Yukinobu; Ikeda, Kazutaka*; et al.
Physical Review Research (Internet), 4(3), p.033215_1 - 033215_9, 2022/09
Kurata, Masaki; Okuzumi, Naoaki*; Nakayoshi, Akira; Ikeuchi, Hirotomo; Koyama, Shinichi
Journal of Nuclear Science and Technology, 59(7), p.807 - 834, 2022/07
Times Cited Count:21 Percentile:95.98(Nuclear Science & Technology)Immediately after the 1F-accident, various attempts have been made to evaluate the fuel debris characteristics toward the decommissioning of 1F. The present review outlines those attempts. In the years immediately following the 1F-accident, the knowledge obtained from the 1F-site (especially from the damaged reactors of Units 1, 2 and 3) was extremely limited. The approximate location of fuel debris was investigated by muon tomography, and its characteristics were roughly estimated based on the past findings such as the results of the Three Mile Island-II accident investigation in the United States, which gave us information of prototypical accident scenarios and debris characteristics for pressurized water reactor accident. After that, various internal investigation robots were developed, and from 2017, investigation of the inside of the reactor containment vessel was started using these robots. Consequently, these three units were found to have core damage status and debris distribution that were rather different from what had been expected based on the typical accident scenario of a pressurized water reactor. In parallel, a small amount of U-bearing particle was recovered from the smear samples of these robots. The analysis of these particles is ongoing to get information relevant to fuel debrsi body. Furthermore, international collaboration is ongoing mainly under OECD/NEA, including accident analysis and debris characterization. From now on, one need to further understand 1F-accident scenario and progress debris characterization based on these 1F-site information.
Koyama, Shinichi; Nakagiri, Toshio; Osaka, Masahiko; Yoshida, Hiroyuki; Kurata, Masaki; Ikeuchi, Hirotomo; Maeda, Koji; Sasaki, Shinji; Onishi, Takashi; Takano, Masahide; et al.
Hairo, Osensui Taisaku jigyo jimukyoku Homu Peji (Internet), 144 Pages, 2021/08
JAEA performed 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 and Thermal Behavior Estimation of Fuel Debris))" in 2020JFY. This presentation summarized briefly the results of the project, which will be available shortly on the website of Management Office for the Project of Decommissioning and Contaminated Water Management.
Go, Shintaro*; Ideguchi, Eiji*; Yokoyama, Rin*; Aoi, Nori*; Azaiez, F.*; Furutaka, Kazuyoshi; Hatsukawa, Yuichi; Kimura, Atsushi; Kisamori, Keiichi*; Kobayashi, Motoki*; et al.
Physical Review C, 103(3), p.034327_1 - 034327_8, 2021/03
Times Cited Count:4 Percentile:44.13(Physics, Nuclear)Nara, Fumiko*; Yokoyama, Tatsunori; Yamasaki, Shinichi*; Minami, Masayo*; Asahara, Yoshihiro*; Watanabe, Takahiro; Yamada, Kazuyoshi*; Tsuchiya, Noriyoshi*; Yasuda, Yoshinori*
Geochemical Journal, 55(3), p.117 - 133, 2021/00
Times Cited Count:6 Percentile:40.44(Geochemistry & Geophysics)The absolute date of the Millennium Eruption (ME) of Changbaishan Volcano is widely recognized as AD 946. The Baegdosan-Tomakomai (B-Tm) tephra dispersed during the ME is a robust-age key bed. In order to identify the tephra, refractive index and major-element compositions of volcanic glass shards are conventionally used. However, trace-element analysis has been rarely carried out, especially for rare-earth elements (REEs) and for tephra layer bulk sediments. Here we present the datasets of major- and trace-element compositions datasets for the glass shards and bulk sediments of the B-Tm and Towada caldera eruptions (To-a) tephra deposits from the Lake Ogawara sediment core, Tohoku region, northern Japan. The depth profiles of the major and trace elements show the significant peaks for the KO and some trace elements (Zn, Rb, Zr, Nb, Sn, Y, La, Ce, Nd, Th, and U) at the B-Tm tephra layer in the Lake Ogawara sediment core, but no peaks of these elements at the To-a tephra layer. High concentrations of the trace elements in the B-Tm tephra layer were observed in individual glass shards as well as in the bulk sediment. These concentrations are highlighted by the elemental abundance pattern normalized by the crustal abundance. The elemental pattern in individual glass shards from other Japanese tephras showed significant differences from those of the B-Tm tephra, especially in REEs compositions. The trace-element compositions of the glass shards and bulk sediment show strong advantages for distinguishing the B-Tm tephra from other Japanese tephras.
Onishi, Takashi; Koyama, Shinichi; Mimura, Hitoshi*
Nihon Ion Kokan Gakkai-Shi, 31(3), p.43 - 49, 2020/10
Washiya, Tadahiro; Koyama, Shinichi; Takano, Masahide; Mitsugi, Takeshi
Denki Hyoron, 105(9), p.64 - 71, 2020/09
For the retrieval of fuel debris in the 1F decommissioning, a retrieval tool and a retrieval method according to the characteristics of fuel debris are being studied. In addition, for stable storage, treatment, and disposal after retrieval, it is necessary to fully understand the characteristics and chemical stability of fuel debris and select appropriate measures. In this paper, we will introduce the characteristics of fuel debris that have been discovered in the previous studies and the problems in handling them.
Tang, T. L.*; Uesaka, Tomohiro*; Kawase, Shoichiro; Beaumel, D.*; Dozono, Masanori*; Fujii, Toshihiko*; Fukuda, Naoki*; Fukunaga, Taku*; Galindo-Uribarri, A.*; Hwang, S. H.*; et al.
Physical Review Letters, 124(21), p.212502_1 - 212502_6, 2020/05
Times Cited Count:18 Percentile:73.39(Physics, Multidisciplinary)The structure of a neutron-rich F nucleus is investigated by a quasifree (
) knockout reaction. The sum of spectroscopic factors of
orbital is found to be 1.0
0.3. The result shows that the
O core of
F nucleus significantly differs from a free
O nucleus, and the core consists of
35%
O
, and
65% excited
O. The result shows that the
O core of
F nucleus significantly differs from a free
O nucleus. The result may infer that the addition of the
proton considerably changes the neutron structure in
F from that in
O, which could be a possible mechanism responsible for the oxygen dripline anomaly.
Simonnet, M.; Suzuki, Shinichi; Miyazaki, Yuji*; Kobayashi, Toru; Yokoyama, Keiichi; Yaita, Tsuyoshi
Solvent Extraction and Ion Exchange, 38(4), p.430 - 440, 2020/00
Times Cited Count:23 Percentile:68.65(Chemistry, Multidisciplinary)Wang, H.*; Otsu, Hideaki*; Chiga, Nobuyuki*; Kawase, Shoichiro*; Takeuchi, Satoshi*; Sumikama, Toshiyuki*; Koyama, Shumpei*; Sakurai, Hiroyoshi*; Watanabe, Yukinobu*; Nakayama, Shinsuke; et al.
Communications Physics (Internet), 2(1), p.78_1 - 78_6, 2019/07
Times Cited Count:10 Percentile:54.23(Physics, Multidisciplinary)Searching for effective pathways for the production of proton- and neutron-rich isotopes through an optimal combination of reaction mechanism and energy is one of the main driving forces behind experimental and theoretical nuclear reaction studies as well as for practical applications in nuclear transmutation of radioactive waste. We report on a study on incomplete fusion induced by deuteron, which contains one proton and one neutron with a weak binding energy and is easily broken up. This reaction study was achieved by measuring directly the cross sections for both proton and deuteron for Pd at 50 MeV/u via inverse kinematics technique. The results provide direct experimental evidence for the onset of a cross-section enhancement at high energy, indicating the potential of incomplete fusion induced by loosely-bound nuclei for creating proton-rich isotopes and nuclear transmutation of radioactive waste.