Random singlet physics in the pyrochlore antiferromagnet NaCdCuF

Kancko, A.*; Sakai, Hironori; Tokunaga, Yo; Colman, R. H.*; 6 of others*

Physical Review Research (Internet), 8(1), p.013344_1 - 013344_11, 2026/03

https://doi.org/10.1103/rw5c-491w

Proceedings of the 12th International Conference on Nuclear Criticality Safety (ICNC2023); October 1-6, 2023, Sendai International Center, Sendai, Miyagi, Japan

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.

Nuclear data as foundation of nuclear research and development

Fukahori, Tokio; Nakayama, Shinsuke; Katabuchi, Tatsuya*; Shigyo, Nobuhiro*

Nihon Genshiryoku Gakkai-Shi ATOMO, 65(12), p.726 - 727, 2023/12

https://doi.org/10.3327/jaesjb.65.12_726

The Investigative Committee on Nuclear Data investigates and observes global trends in nuclear research and development and conducts comprehensive examinations of Japanese nuclear data activities from a broader perspective, as well as cooperation with domestic and foreign academic institutions in a wide range of fields other than the Atomic Energy Society. We aim to establish a system for communication, information exchange, and interdisciplinary cooperation. In this report, we will report on three of the main activities for the 2021-2022 term: a request list site for nuclear data, human resource development, and roadmap production.

Establishing an evaluation method for the aging phenomenon by physical force in fuel debris

Suzuki, Seiya; Arai, Yoichi; Okamura, Nobuo; Watanabe, Masayuki

Journal of Nuclear Science and Technology, 60(7), p.839 - 848, 2023/07

https://doi.org/10.1080/00223131.2022.2159559

The fuel debris, consisting of nuclear fuel materials and reactor structural materials, generated in the accident of Fukushima Daiichi Nuclear Power Plant can become deteriorated like rocks under the changes of environmental temperature. Although the fuel debris have been cooled by water for 10 years, they are affected by seasonal and/or day-and-night temperature changes. Therefore, in evaluating the aging behavior of the fuel debris, it is essential to consider the changes in environmental temperature. Assuming that the fuel debris are deteriorated, radioactive substances that have recently undergone micronization could be eluted into the cooling water, and such condition may affect defueling methods. We focused on the effect of repeated changes in environmental temperature on the occurrence of cracks, and an accelerated test using simulated fuel debris was carried out. The length of the crack increases with increasing number of heat cycle; therefore, the fuel debris become brittle by stress caused by thermal expansion and contraction. In conclusion, it was confirmed that the mechanical deterioration of the fuel debris is similar to that of rocks or minerals, and it became possible to predict changes in the length of the crack in the simulated fuel debris and environmental model.

Estimation of the in-depth debris status of Fukushima Unit-2 and Unit-3 with Multi-physics modeling (Contract research); FY2021 Nuclear Energy Science & Technology and Human Resource Development Project

Collaborative Laboratories for Advanced Decommissioning Science; Waseda University*

JAEA-Review 2022-054, 150 Pages, 2023/02

JAEA-Review-2022-054.pdf:7.26MB

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. (hereafter referred to "1F"). 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 "Estimation of the in-depth debris status of Fukushima Unit-2 and Unit-3 with multi-physics modeling" conducted from FY2019 to FY2021. Since the final year of this proposal was FY2021, the results for three fiscal years were summarized. Continuous update on understanding of the damaged 1F reactors is important for safe and efficient decommissioning of the reactors. This study aimed to estimate the in-depth debris status of the damaged 1F Unit-2 and Unit-3 through multi-physics modeling, which comprises of MPS method, simulated molten debris relocation experiment and high-temperature melt property data acquisition in the three-year project from FY2019.

Estimation of the in-depth debris status of Fukushima Unit-2 and Unit-3 with Multi-physics modeling (Contract research); FY2020 Nuclear Energy Science & Technology and Human Resource Development Project

Collaborative Laboratories for Advanced Decommissioning Science; Waseda University*

JAEA-Review 2021-034, 107 Pages, 2021/12

JAEA-Review-2021-034.pdf:6.08MB

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 FY2020. 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 FY2019, this report summarizes the research results of the "Estimation of the in-depth debris status of Fukushima Unit-2 and Unit-3 with multi-physics modeling" conducted in FY2020. Continuous update on understanding of the damaged 1F reactors is important for safe and efficient decommissioning of the reactors. This study aims to estimate the in-depth debris status of the damaged 1F Unit-2 and Unit-3 through multi-physics modeling, which comprises of MPS method, simulated molten debris relocation experiment and high-temperature melt property data acquisition in the three-year project from FY2019.

Thermophysical properties of austenitic stainless steel containing boron carbide in a solid state

Takai, Toshihide; Furukawa, Tomohiro; Yamano, Hidemasa

Mechanical Engineering Journal (Internet), 8(4), p.20-00540_1 - 20-00540_11, 2021/08

https://doi.org/10.1299/mej.20-00540

In a core disruptive accident scenario, boron carbide, which is used as a control rod material, may melt below the melting temperature of stainless steel owing to the eutectic reaction with them. The eutectic mixture produced is assumed to extensively relocate in the degraded core, and this behavior plays an important role in significantly reducing the neutronic reactivity. However, these behaviors have never been simulated in previous severe accident analysis. To contribute to the improvement of the core disruptive accident analysis code, the thermophysical properties of the eutectic mixture in the solid state were measured, and regression equations that show the temperature (and boron carbide concentration) dependence are created.

Estimation of the in-depth debris status of Fukushima Unit-2 and Unit-3 with Multi-physics modeling (Contract research); FY2019 Nuclear Energy Science & Technology and Human Resource Development Project

Collaborative Laboratories for Advanced Decommissioning Science; Waseda University*

JAEA-Review 2020-035, 102 Pages, 2021/01

JAEA-Review-2020-035.pdf:6.82MB

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 FY2019. 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 "Estimation of the In-Depth Debris Status of Fukushima Unit-2 and Unit-3 with Multi-Physics Modeling". Continuous update on understanding of the damaged Fukushima reactors is important for safe and efficient decommissioning of the reactors. This study aims to estimate the in-depth debris status of the damaged Fukushima Unit-2 and Unit-3 through multi-physics modeling, which comprises of MPS method, simulated molten debris relocation experiment and high-temperature melt property data acquision in the three-year project from FY2019.

Japan's experience in mitigating the impact of COVID-19 on NSSC operations

Inoue, Naoko

IAEA NSSC Network Newsletter (Internet), (6), 5 Pages, 2020/10

https://www.iaea.org/sites/default/files/20/11/nssc6_in_focus_article_oct2020.pdf

ISCN/JAEA has conducted roughly 20 trainings/workshops with 500 participants every year, for capacity building support for nuclear nonproliferation and nuclear security since its establishment in December 2010. In 2020, four trainings for Asian countries were postponed because of the restriction of overseas travels and entry into Japan by COVID-19. ISCN/JAEA decided to develop the online trainings of two major ones, Physical Protection regional training and State System of Nuclear Material Accountancy for and Control for IAEA safeguards, in order to mitigate the impact of COVID-19. The period of two weeks as in-person trainings are maintained as online ones. It consists of the interactive modules using a web meeting tool, Zoom meeting, and E-learning (self-learning) modules. Breakout function is used for the sub-group exercises which part of the interactive modules. Number of knowledge and lesson learned were obtained through the development and implementation of the online training as well as many challenges were identified. The online trainings are not just a mitigation measure against COVID-19, but they are the opportunities for development of new trainings. ISCN/JAEA will address further in expanding the new training menu cased on the experiences.

Introduction to nuclear security, 2; Efforts to strengthen nuclear security

Suda, Kazunori; Kimura, Takashi

Nihon Genshiryoku Gakkai-Shi ATOMO, 62(6), p.334 - 338, 2020/06

https://doi.org/10.3327/jaesjb.62.6_334

Amid growing concerns about potential nuclear terrorism, discussions have been conducted internationally to strengthen the nuclear security. In this series, we will explain the efforts of the international community to strengthen the nuclear security and the reflection of the treaty for the nuclear security and the IAEA nuclear security recommendations in the domestic laws.