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neutron diffraction mapping measurementYamashita, Takayuki*; Nagira, Tomoya*; Gong, W.; Kawasaki, Takuro; Harjo, S.; Ushioda, Kosaku*; Fujii, Hidetoshi*
ISIJ International, 66(5), p.673 - 684, 2026/04
Times Cited Count：0 Percentile：0.00(Metallurgy & Metallurgical Engineering)Matsui, Tetsuya; Shimodaira, Masaki; Yamaguchi, Yoshihito; Toyama, Takeshi; Katsuyama, Jinya
JAEA-Research 2025-017, 41 Pages, 2026/03
JAEA-Research-2025-017.pdf:4.52MB
The JAEA Safety Research Center has been conducting fundamental research on advanced inspection and structural integrity assessment technologies since FY2024, including the development of a machine-learning-based ultrasonic flaw detection method using an ultrasonic simulator. To assess the simulator's applicability, phased array ultrasonic testing (PAUT) results produced by the simulator were compared with actual measurement data. Due to limited publicly available datasets, an intergranular crack in the pressurizer spray line piping of Kansai Electric Power Co. Inc.'s Ohi Nuclear Power Station Unit 3 was selected as the reference case. PAUT linear scanning analysis at a 45
incident angle detected the crack's corner and edge echoes. Strong columnar-crystal propagation echoes were also observed within the weld metal, with their intensity showing dependence on the symmetric axis angle. Analysis at a 31 incident angle similarly identified strong columnar-crystal propagation echoes, which connected to the crack's corner echoes and propagated into the weld region. These results align with actual measurements, indicating that the observed weld-metal echoes are likely attributable to columnar-crystal propagation.
Yamazaki, Takumi*; Ishitani, Yugo*; Nakada, Katsuyuki*; Sasaki, Tomoyuki*; Endo, Yasushi*; Takanashi, Koki; Seki, Takeshi*
Journal of Applied Physics, 138(23), p.233905_1 - 233905_11, 2025/12
Times Cited Count：0 Percentile：0.00(Physics, Applied) neutron diffraction mapping measurementYamashita, Takayuki*; Nagira, Tomoya*; Gong, W.; Kawasaki, Takuro; Harjo, S.; Ushioda, Kosaku*; Fujii, Hidetoshi*
Tetsu To Hagane, 111(17), p.1057 - 1071, 2025/12
Ichihara, Yoshitaka*; Nakamura, Naohiro*; Nabeshima, Kunihiko*; Choi, B.; Nishida, Akemi
Nuclear Engineering and Design, 441, p.114160_1 - 114160_10, 2025/09
Times Cited Count：3 Percentile：70.03(Nuclear Science & Technology)This paper evaluates the applicability of equivalent linear analysis of reinforced concrete model, which uses frequency-independent complex damping with a small computational load, to the seismic design of nuclear power plant reactor buildings. To this end, a three-dimensional finite element method analysis of the soil-structure interaction focusing on nonlinear and equivalent linear seismic behavior of the building embedded in an ideally uniform soil condition was performed for the Kashiwazaki-Kariwa Nuclear Power Plant Unit 7 reactor building. The equivalent linear analysis results correlated well with the nonlinear analysis results of the shear strain, acceleration, displacement, and acceleration response spectrum, demonstrating the effectiveness of the equivalent linear analysis method. Moreover, the equivalent linear analysis results were more conservative than those of nonlinear analysis using the material constitutive law in evaluating the shear strain of the external wall of the reactor building. From this result, equivalent linear analysis method tended to obtain a lower building stiffness than nonlinear analysis under the analysis conditions used in this paper.
Takeda, Takeshi
Nihon Genshiryoku Gakkai-Shi ATOMO
, 67(7), p.407 - 410, 2025/07
no abstracts in English
Ikesue, Shunichi*; Iwasaki, Akihisa*; Sago, Hiromi*; Yokoi, Shinobu*; Yamamoto, Tomohiko
Proceedings of the ASME 2025 Pressure Vessels & Piping Conference (PVP2025) (Internet), 10 Pages, 2025/07
Tomioka, Dai; Kochiyama, Mami; Ozone, Kenji; Nakata, Hisakazu; Sakai, Akihiro
JAEA-Technology 2024-023, 38 Pages, 2025/03
JAEA-Technology-2024-023.pdf:1.54MB
Japan Atomic Energy Agency is an implementing organization of near-surface disposal for low-level radioactive wastes generated from research, industrial and medical facilities in Japan. Information on the radioactivity concentration of these radioactive wastes is dispensable for the design and conformity assessment of the waste disposal facilities for the licensing application of the disposal project and its safety review. Radioactive Wastes Disposal Center has been improving the radioactivity evaluation procedure for the dismantling waste generated from the research reactors based on the activation calculation. In order to investigate the applicability of the ORIGEN code (included in SCALE6.2.4), which enables more accurate activation calculations using multigroup neutron spectra, we performed activation calculations with the ORIGEN-code and the ORIGEN-S code (included in SCALE6.0), which has been widely used in the past, for the dismantled wastes from the Rikkyo University Research Reactor, where radioactivity analysis data for the structural materials around the reactor core were compiled. As a result, the calculation time difference between ORIGEN and ORIGEN-S was small and the evaluated radioactivity concentrations of the former were in the range of 0.8-1.0 times those of the latter, which was in good agreement with those of radiochemical analysis in the range of 0.5-3.0 times. The applicability of ORIGEN was confirmed. In addition, activation calculations assuming trace elements in structural materials of nuclear reactor were performed with ORIGEN and ORIGEN-S and the results were compared. The causes of the large differences among 170 nuclides that are important for dose assessment in near-surface disposal were assessed each nuclide.
Minowa, Kazuki*; Watanabe, So; Nakase, Masahiko*; Takahatake, Yoko; Miyazaki, Yasunori; Ban, Yasutoshi; Matsuura, Haruaki*
Nuclear Instruments and Methods in Physics Research B, 556, p.165496_1 - 165496_6, 2024/11
Times Cited Count：0 Percentile：0.00(Instruments & Instrumentation)In this study, X-ray absorption near edge structure (XANES) spectral analysis and column experiments were used to verify the selectivity of rare earth (RE) ions by alkyl diamide amine (ADAAM) adsorbent. In addition, the interactions between the N atoms of ADAAM and RE ions were evaluated to determine whether any of the RE ions are a valid simulant for developing a mutual separation process for minor actinides (MAs) in highly radioactive liquid waste. It was confirmed that La and Ce interacted with the amine N atom of ADAAM and they showed a peak shift of the N-K edge XANES spectrum; this finding suggested that a soft interaction is an essential factor influencing ion selectivity. Therefore, the selection factor of RE ions by ADAAM adsorbent was similar to that of MAs. It was concluded that RE ions are reasonable species to simulate MAs.
Iwata, Yoshihiro; Miyabe, Masabumi; Wells, S. R.*; Yamamoto, Yuta*; Hasegawa, Shuichi*
Proceedings of International Topical Workshop on Fukushima Decommissioning Research 2024 (FDR2024) (Internet), 4 Pages, 2024/10
In this study, triple and double resonance ionization schemes of atomic Ca were developed, aiming for the separation of odd isotopes by (i) laser polarization-dependent selection rules, and (ii) large isotope shifts of odd Ca isotopes in the Rydberg levels. Separation of odd isotopes was confirmed under the orthogonal condition. Suppression of non-resonant ionization of 
Ca by the electric field in the ionization region could further improve the optical isotope selectivity of 
Ca.
Takeda, Takeshi; Shibata, Taiju
JAEA-Review 2024-040, 29 Pages, 2024/09
JAEA-Review-2024-040.pdf:1.33MB
An important theme of Japan's 6th strategic energy plan is to indicate the energy policy path towards carbon neutrality by 2050. Policy responses for Japan's nuclear energy research and development (R&D) towards 2030 contain the demonstrations of technologies for small modular reactors (SMRs) through international cooperation by 2030. In light of this energy plan, basic policy initiatives over the next 10 years have been compiled to realize Green Transformation (GX), which simultaneously achieves decarbonization and economic growth. Looking overseas, activities of SMR R&D are active internationally, mainly in the US, Canada, Europe, China, and Russia. These activities are not only by heavy industry manufactures and R&D institutes, but also by venture companies. Under these circumstances, the NEA CSNI has gathered an Expert Group on SMRs (EGSMR) to help estimate the safety effects of SMRs. The EGSMR efforts required the submission of responses to several questionnaires whose main purpose was to collect the latest information on the efforts of SMR deployment and research. The first author of this report responded to this based on information from Hitachi-GE Nuclear Energy, Ltd. and Mitsubishi Heavy Industries, Ltd. as well as JAEA. Most of the responses from Japan to the questionnaires are the information that serves as the basis of CSNI Technical Opinion Paper No. 21 (TOP-21). In this report, the Japan's publicly available responses to the questionnaires arranged and additional information are explained, which complements some of the content of the TOP-21. In this manner, the investigation results of R&D related to SMR in Japan, focusing on the EGSMR activities (2022-2023), are summarized. The target of this report is to provide useful information for future discussions on international cooperation concerning SMR as well as nuclear power field human resources development internationally and domestically.
Suyama, Kenya; Gunji, Satoshi; Watanabe, Tomoaki; Araki, Shohei; Fukuda, Kodai; Shimada, Kazuya; Fujita, Tatsuya; Ueki, Taro; Nguyen, H. H.
JAEA-Conf 2024-001, 40 Pages, 2024/07
JAEA-Conf-2024-001.pdf:1.28MB
JAEA-Conf-2024-001-appendix(CD-ROM).zip:163.97MB
The 12th International Conference on Nuclear Criticality Safety (ICNC2023) was held from October 1 to October 6, 2023, at the Sendai International Center (Aobayama, Aoba-ku, Sendai, Miyagi-prefecture 980-0856, Japan), organized by Japan Atomic Energy Agency (JAEA) and co-organized by the Reactor Physics Division of the Atomic Energy Society of Japan (AESJ) and the Nuclear Energy Agency of the Organization for Economic Co-operation and Development (OECD/NEA). 224 presentations passed peer review and 273 technical session registrations, bringing the total number of registered participants to 289, including accompanying persons. Technical tours were also conducted to i) Fukushima Daiichi Nuclear Power Station of TEPCO holdings and Interim Storage Facility Information Center, ii) Nuclear Science Research Institute of JAEA (STACY Renewable Reactor and FCA), iii) NanoTerasu of Tohoku University (synchrotron radiation facility) and Onagawa Nuclear Power Station of Tohoku Electric Power Co., Inc. This report summarizes the conference and compiles the papers that were presented and agreed to be published in the Proceedings.
Ikesue, Shunichi*; Iwasaki, Akihisa*; Sago, Hiromi*; Yokoi, Shinobu*; Yamamoto, Tomohiko
Proceedings of the ASME 2024 Pressure Vessels & Piping Conference (PVP 2024) (Internet), 9 Pages, 2024/07
Aono, Ryuji; Haraga, Tomoko; Kameo, Yutaka
JAEA-Technology 2024-006, 48 Pages, 2024/06
JAEA-Technology-2024-006.pdf:1.77MB
In the future, radioactive waste which generated from nuclear research facilities in Japan Atomic Energy Agency are planning to be buried for the near surface disposal. It is necessary to establish the method to evaluate the radioactivity concentrations of the radioactive wastes. In this work, we studied the evaluation methodology of the radioactivity concentrations in concrete waste generated from JPDR. In order to construct the evaluation methodology of the radioactivity concentration, the validity of the evaluation methods was confirmed by mainly theoretical calculation and using the result of radiochemical analysis. Correcting the theoretical calculations using results of nuclide analysis, it is possible to evaluate the radioactivity concentrations of nuclides preliminary selected.
Project Promotion Department; Radioactive Wastes Disposal Center
JAEA-Review 2023-037, 162 Pages, 2024/02
JAEA-Review-2023-037.pdf:2.66MB
For near surface disposal of radioactive wastes generated from research, industrial and medical facilities, Japan Atomic Energy Agency has discussed methods for corresponding to the technical standards on confirmation related to waste disposal, etc. From FY2022, we have established Waste Standards Committee and interim Waste Acceptance Criteria, Waste Package Confirmation Procedure, etc. have been considered. In FY2022, Waste Package Confirmation Procedures of solidified liquid waste and cement filled waste and related standards were discussed. In addition, issues of preparation of Waste Package Confirmation Procedure and rational treatment method for decommissioning wastes were considered. This annual report summarizes the results of discussion in FY2022.
Ikesue, Shunichi*; Morita, Hideyuki*; Sago, Hiromi*; Yokoi, Shinobu*; Yamamoto, Tomohiko
Proceedings of the ASME 2023 Pressure Vessels and Piping Conference (PVP 2023) (Internet), 10 Pages, 2023/07
Sakai, Akihiro
Dekomisshoningu Giho, (64), p.24 - 33, 2023/05
Japan Atomic Energy Agency (JAEA) has proceeded with the project of near surface disposal of radioactive waste generated from research facilities, etc. as the implementing body. On the other hand, Nuclear Regulation Authority (NRA) has established the safety regulations and standards for the operation of the disposal facilities. This report outlines the disposal project of JAEA and the development of the regulations and standards for the disposal by NRA.
Sakai, Akihiro
Dai-33-Kai Genshiryoku Shisetsu Dekomisshoningu Gijutsu Koza Tekisuto, p.31 - 63, 2023/02
The Japan Atomic Energy Agency (JAEA) is promoting the project for concrete-vault disposal and landfill-type disposal of radioactive waste generated from research facilities, etc. This report introduces current status of technical development for JAEA's disposal project as following items; (1) kinds of research facilities and characteristics of radioactivity inventory of the waste, (2) the structures of the disposal facilities which JAEA conceptually designed, (3) development of waste acceptance criteria for major radioactive waste for the JAEA disposal facilities, (4) the concept of the criteria for disposal of uranium bearing waste, that has been established in 2021.
Collaborative Laboratories for Advanced Decommissioning Science; National Institutes for Quantum Science and Technology*
JAEA-Review 2022-051, 78 Pages, 2023/01
JAEA-Review-2022-051.pdf:7.12MB
The Collaborative Laboratories for Advanced Decommissioning Science (CLADS), Japan Atomic Energy Agency (JAEA), had been conducting the Nuclear Energy Science & Technology and Human Resource Development Project (hereafter referred to "the Project") in FY2021. The Project aims to contribute to solving problems in the nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. (TEPCO). For this purpose, intelligence was collected from all over the world, and basic research and human resource development were promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barrier of conventional organizations and research fields. The sponsor of the Project was moved from the Ministry of Education, Culture, Sports, Science and Technology to JAEA since the newly adopted proposals in FY2018. On this occasion, JAEA constructed a new research system where JAEA-academia collaboration is reinforced and medium-to-long term research/development and human resource development contributing to the decommissioning are stably and consecutively implemented. Among the adopted proposals in FY2019, this report summarizes the research results of the "Establishing a new evaluation system to characterize radiation carcinogenesis by stem cell dynamics" conducted from FY2019 to FY2021. Since the final year of this proposal was FY2021, the results for three fiscal years were summarized. In this study, we will use cell lineage tracing technology that can permanently label stem cells and their progenies to capture and mathematically model the long-term clonal proliferation of cells in mammary tissue after high to low dose radiation exposure to determine the origin of radiation carcinogenesis, the stem cells. The objective is to characterize radiation-induced breast cancer by its dynamics.
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.
