In situ study of growth mechanism of germanene segregated through Ag(111) thin films by Raman and X-ray photoelectron spectroscopy

Terasawa, Tomoo; Katsube, Daiki*; Yano, Masahiro; Ozawa, Takahiro*; Tsuda, Yasutaka; Yoshigoe, Akitaka; Asaoka, Hidehito; Suzuki, Seiya

Chemistry of Materials, 38(6), p.2933 - 2945, 2026/03

AA2025-0822.pdf:1.33MB

https://doi.org/10.1021/acs.chemmater.5c03462

Clarification of debris formation conditions on the basis of the sampling data and experimental study using simulated fuel debris and reinforcement of the analytical results of severe accident scenario (Contract research); FY2023 Nuclear Energy Science & Technology and Human Resource Development Project

Collaborative Laboratories for Advanced Decommissioning Science; University of Fukui*

JAEA-Review 2025-007, 120 Pages, 2025/09

JAEA-Review-2025-007.pdf:8.13MB

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 FY2023. The Project aims to contribute to solving problems in the nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station (1F), 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 FY2021, this report summarizes the research results of the "Clarification of debris formation conditions on the basis of the sampling data and experimental study using simulated fuel debris and reinforcement of the analytical results of severe accident scenario" conducted from FY2021 to FY2023. The present study aims to clarify the debris formation mechanism and utilize the results to refine the accident scenario. In the backward analysis of oxide debris formation, we prepared simulated fuel particles by the aerodynamic levitation method and ejection of melted oxides from a tungsten pipe with a small hole and summarized the relationship between preparation conditions and the properties of the particles. We also demonstrated the formation of simulated fuel debris obtained by the sampling in 1F and clarified the difference between the experimental results and thermodynamic calculation. From the estimation of mixing, melting and solidified states of metallic debris, it was found that the formation of thin reaction layer suppresses the damage of SUS in spite of Zr content around 1000 C, and we quantify the elution rate of BC and Zircaloy to the melted SUS. We extended reaction rate data between various pressure vessel with SUS and Zr and welding parts and suggested reaction rate equation for large scale experiment. We also estimated the failure behavior of lower plenum of pressure vessel and outflow behavior of melt. Furthermore, we estimated transition behavior of Uranium melt to metallic debris melt in the re-melting process of predropped metallic debris. As the experimental techniques in the future, we prepared the semi-melted debris from oxide and metals and analyzed the reaction products and discussed the formation of simulated debris with a small amount of uranium oxide using a CCIM furnace and the aerodynamic levitation method.

Clarification of debris formation conditions on the basis of the sampling data and experimental study using simulated fuel debris and reinforcement of the analytical results of severe accident scenario (Contract Research); FY2022 Nuclear Energy Science & Technology and Human Resource Development Project

Collaborative Laboratories for Advanced Decommissioning Science; University of Fukui*

JAEA-Review 2024-014, 112 Pages, 2024/08

JAEA-Review-2024-014.pdf:8.22MB

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 FY2022. The Project aims to contribute to solving problems in the nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station (1F), 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 FY2021, this report summarizes the research results of the "Clarification of debris formation conditions on the basis of the sampling data and experimental study using simulated fuel debris and reinforcement of the analytical results of severe accident scenario" conducted in FY2022. The present study aims to clarify the debris formation mechanism and utilize the results to refine the accident scenario. In the backward analysis of oxide debris formation, we succeeded in the formation of simulated fuel particle by the aerodynamic levitation method and ejection of melted oxides from tungsten pipe with a small hole. And we demonstrated the formation of simulated fuel debris of U1-No.15 obtained by the sampling in 1F.

Attention-based time series analysis for data-driven anomaly detection in nuclear power plants

Dong, F.*; Chen, S.*; Demachi, Kazuyuki*; Yoshikawa, Masanori; Seki, Akiyuki; Takaya, Shigeru

Nuclear Engineering and Design, 404, p.112161_1 - 112161_15, 2023/04

https://doi.org/10.1016/j.nucengdes.2023.112161

Consideration on modeling of Nb sorption onto clay minerals

Yamaguchi, Tetsuji; Ohira, Saki; Hemmi, Ko; Barr, L.; Shimada, Asako; Maeda, Toshikatsu; Iida, Yoshihisa

Radiochimica Acta, 108(11), p.873 - 877, 2020/11

https://doi.org/10.1515/ract-2020-0006

Challenges for management of radioactively contaminated wastes and volume reduction and reuse/recycling of removed soil derived from the activities for environmental remediation after the Fukushima Daiichi Nuclear Power Station accident, 2; Cs adsorption and desorption mechanism on clay minerals for aiming reuse

Yaita, Tsuyoshi

Nihon Genshiryoku Gakkai-Shi ATOMO, 59(8), p.441 - 443, 2017/08

no abstracts in English

Mechanism of stabilization of ballooning modes by toroidal rotation shear in tokamaks

Furukawa, Masaru; Tokuda, Shinji

Physical Review Letters, 94(17), p.175001_1 - 175001_4, 2005/05

https://doi.org/10.1103/PhysRevLett.94.175001

A ballooning perturbation in a toroidally rotating tokamaks is expanded by square-integrable eigenfunctions of an eigenvalue problem associated with ballooning modes in a static plasma. Especially a weight function is chosen such that the eigenvalue problem has only the discrete spectrum. The eigenvalues evolve in time owing to toroidal rotation shear, resulting in countably infinite number of crossings among them. The crossings cause energy transfer from an unstable mode to the infinite number of stable modes; such transfer works as the stabilization mechanism of the ballooning mode.

Migration mechanisms of Np and Am through loess media

Tanaka, Tadao; Mukai, Masayuki; Maeda, Toshikatsu; Matsumoto, Junko; Ogawa, Hiromichi; Li, Z.*; Wang, X.*; Fan, Z.*; Guo, L.*; Liu, C.*

Journal of Radioanalytical and Nuclear Chemistry, 256(2), p.205 - 211, 2003/05

https://doi.org/10.1023/A:1023916829838

Migration experiments of Np(V) and Am(III) have been performed using a column system, to investigate migration behavior of Np and Am through a column packed with loess, taken from Shanxi, China. Adsorption mechanisms of Np and Am on the loess were examined by a chemical extraction method. In the case of the Np, most of Np adsorbed on the influent edge of the column. The Np adsorbed on the loess was mainly controlled by surface complexation. However, the migration of Np in the loess media could be roughly evaluated by using the distribution coefficient. In the case of the Am, particulate Am species was formed in the influent solution and moved in the column. The Am adsorbed on the loess was controlled by irreversible reactions. The migration behavior of particulate Am in the loess media could be expressed by the filtration theory.

Research on the fundamental process of thermal-hydraulic behaviors in severe accident; Breakup and cooling of molten material jets, JAERI's nuclear research promotion program, H10-027-2 (Contract research)

Sugiyama, Kenichiro*; Iguchi, Kentaro*

JAERI-Tech 2002-010, 67 Pages, 2002/03

JAERI-Tech-2002-010.pdf:4.4MB

no abstracts in English

Enhanced decomposition of dichloromethane in air by multi-pass electron beam irradiation

Wahyuni, S.*; Hirota, Koichi; Hakoda, Teruyuki; Arai, Hidehiko; Hashimoto, Shoji; Kawamoto, Fumio*; Mukunoki, Yasuo*

Bulletin of the Chemical Society of Japan, 73(8), p.1939 - 1943, 2000/08

https://doi.org/10.1246/bcsj.73.1939

no abstracts in English