Study on water stopping, repair and stabilization of lower PCV by geopolymer, etc. (Contract research); FY2022 Nuclear Energy Science & Technology and Human Resource Development Project

Collaborative Laboratories for Advanced Decommissioning Science; The University of Tokyo*

JAEA-Review 2024-021, 126 Pages, 2024/11

JAEA-Review-2024-021.pdf:6.51MB

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, 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 "Study on water stopping, repair and stabilization of lower PCV by geopolymer, etc" conducted in FY2022. The present study aims to propose a construction method to stop jet deflectors by improved geopolymer and ultra-heavy muddy water, and to repair the lower part of the dry well. In addition, in order to increase the options for on-site construction in unknown situations such as deposition conditions, we will examine a wide range of construction outside the pedestal, and evaluate the feasibility of the construction method by the latest thermal flow simulation method.

Quantitative evaluation of long-term state changes of contaminated reinforced concrete considering the actual environments for rational disposal (Contract research); FY2022 Nuclear Energy Science & Technology and Human Resource Development Project

Collaborative Laboratories for Advanced Decommissioning Science; The University of Tokyo*

JAEA-Review 2024-011, 121 Pages, 2024/09

JAEA-Review-2024-011.pdf:5.42MB

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, 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 FY2020, this report summarizes the research results of the "Quantitative evaluation of long-term state changes of contaminated reinforced concrete considering the actual environments for rational disposal" conducted from FY2020 to FY2022. Estimating waste volume and concentration is essential for decommissioning concrete structures at the Fukushima Daiichi Nuclear Power Station.

Multi-modal 3D image-based simulation of hydrogen embrittlement crack initiation in Al-Zn-Mg alloy

Higa, Ryota*; Fujihara, Hiro*; Toda, Hiroyuki*; Kobayashi, Masakazu*; Ebihara, Kenichi; Takeuchi, Akihisa*

Materials Transactions, 65(8), p.899 - 906, 2024/08

https://doi.org/10.2320/matertrans.MT-L2024007

It is indispensable to suppress hydrogen embrittlement (HE) to develop the strength of the Al-Zn-Mg alloy. Because intergranular fracture (IGF) is mainly observed when HE occurs in the alloy, we need to understand the IGF initiation to suppress HE. In the present study, we investigated the stress, strain, and H concentration, which influence the IGF initiation, in actual fractured regions by simulation of a crystal plasticity finite element method and H diffusion analysis in a 3D image-based model, which was created based on 3D polycrystalline microstructure data obtained from X-ray imaging technique. Combining the simulation and in-situ observation of the tensile test sample by X-ray CT, we examined the stress, strain, and H concentration, and discussed the IG crack initiation condition. As a result, it is revealed that stress normal to grain boundary induced by crystal plasticity dominates IG crack initiation while the accumulation of H due to stress has little impact on it.

Earthquake resistance by improvement construction for ground around High Active liquid Waste facility in Tokai Reprocessing Plant

Yokochi, Masaru; Sasaki, Shunichi; Yanagibashi, Futoshi; Asada, Naoki; Komori, Tsuyoshi; Fujieda, Sadao; Suzuki, Hisanori; Takeuchi, Kenji; Uchida, Naoki

Nihon Hozen Gakkai Dai-20-Kai Gakujutsu Koenkai Yoshishu, p.1 - 4, 2024/08

Tokai Reprocessing Plant, which is shifted to decommissioning stage, stores large amount of high-level radioactive liquid waste (HLLW) generated by reprocessing of spent nuclear fuels in High-level Active Waste facility (HAW). Radioactive risk related to HLLW has been concentrated in HAW until the completion of vitrification. Natural disasters such as earthquake may damage cooling function of HAW. Therefore, HAW must improve earthquake resistance, as exchanging the ground around HAW facility and pipe trench by concrete. This earthquake resistance construction starts from July of 2020 and completed in March 2024. This report summarizes the construction work and describes the inspection results after the construction.

Room-temperature flexible manipulation of the quantum-metric structure in a topological chiral antiferromagnet

Han, J.*; Uchimura, Tomohiro*; Araki, Yasufumi; Yoon, J.-Y.*; Takeuchi, Yutaro*; Yamane, Yuta*; Kanai, Shun*; Ieda, Junichi; Ohno, Hideo*; Fukami, Shunsuke*

Nature Physics, 20(7), p.1110 - 1117, 2024/07

https://doi.org/10.1038/s41567-024-02476-2

Quantum metric and Berry curvature are two fundamental and distinct factors to describe the geometry of quantum eigenstates. While Berry curvature is known for playing crucial roles in several condensed-matter states, quantum metric, which was predicted to induce new classes of topological phenomena, has rarely been touched, particularly in an ambient circumstance. Using a topological chiral antiferromagnet MnSn adjacent to Pt, at room temperature, we successfully manipulate the quantum-metric structure of electronic states through its interplay with the nanoscale spin texture at the MnSn/Pt interface. This is manifested by a time-reversal-odd second-order Hall effect that is robust against extrinsic electron scattering, in contrast to any transport effects from the Berry curvature. We also verify the flexibility of controlling the quantum-metric structure, as the interacting spin texture can be tuned by moderate magnetic fields or by interface engineering via spin-orbit interactions. Our work paves a way for harnessing the quantum-metric structure to unveil emerging topological physics in practical environments and to build applicable nonlinear devices.

Proposal of a new flaw-to-surface proximity rule for the re-characterization of a subsurface flaw into a surface flaw

Lacroix, V.*; Dulieu, P.*; Hasegawa, Kunio

Proceedings of ASME 2024 Pressure Vessels & Piping Conference (PVP 2024) (Internet), 5 Pages, 2024/07

When a subsurface flaw is detected close to the surface of a pressure retaining component, the subsurface flaw shall be transformed into a surface flaw in accordance with flaw to surface proximity rules. This re-characterization process from subsurface to surface flaw is adopted in ASME Code Section XI. The limit value for this proximity rule depends on ratio between the subsurface flaw to the free surface distance and the flaw depth. This limit value does not depend on the flaw aspect ratio. This paper proposes an interaction limit criterion and presents a new limit value for the flaw-to-surface proximity factor, depending on the flaw depth, the remaining ligament and the flaw aspect ratio.

New isomeric transition in Mg; Bridging the and islands of inversion

Madurga, M.*; Christie, J. M.*; Xu, Z.*; Grzywacz, R.*; Poves, A.*; King, T.*; Allmond, J. M.*; Chester, A.*; Cox, I.*; Farr, J.*; et al.

Physical Review C, 109(6), p.L061301_1 - L061301_6, 2024/06

https://doi.org/10.1103/PhysRevC.109.L061301

no abstracts in English

Progress of sodium-cooled fast reactor developments in Japan taking into account total lifecycle, risk-informed approach, and sustainability

Kamide, Hideki; Asayama, Tai; Wakai, Takashi; Ezure, Toshiki; Uchibori, Akihiro; Kubo, Shigenobu; Takeuchi, Masayuki

Nuclear Engineering and Design, 421, p.113062_1 - 113062_10, 2024/05

https://doi.org/10.1016/j.nucengdes.2024.113062

A sodium cooled fast reactor (SFR) is one of the most relevant and decarbonized energy supply system with higher sustainability on natural resources, footprint, and waste management. It was planned in a strategic roadmap of fast reactor decided by Inter-Ministerial Council for Nuclear Power Japan in 2022 to start a conceptual design of a demonstration reactor from 2024 with a background of accumulated knowledge and experiences of SFR development. For example, a design and lifecycle simulation/evaluation system named ARKADIA has been developed to accelerate such design works. It will enable to take into account plant lifecycle, e.g., operation and maintenance, to the plant design and optimize it based on simulations and knowledgebase. This paper shows research progresses of ARKADIA, safety design and evaluations, codes and standards, fuel cycle, and SFR development projects in Japan.

Overview of development program for engineering scale extraction chromatography MA(III) recovery system

Watanabe, So; Takahatake, Yoko; Hasegawa, Kenta; Goto, Ichiro*; Miyazaki, Yasunori; Watanabe, Masayuki; Sano, Yuichi; Takeuchi, Masayuki

Mechanical Engineering Journal (Internet), 11(2), p.23-00461_1 - 23-00461_10, 2024/04

https://doi.org/10.1299/mej.23-00461

Human resource development related to remote control technology for monitoring inside RPV pedestal during retrieval of fuel debris (Contract research); FY2022 Nuclear Energy Science & Technology and Human Resource Development Project

Collaborative Laboratories for Advanced Decommissioning Science; The University of Tokyo*

JAEA-Review 2023-023, 99 Pages, 2024/03

JAEA-Review-2023-023.pdf:6.0MB

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, 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 "Human Resource Development Related to Remote Control Technology for Monitoring Inside RPV Pedestal during Retrieval of Fuel Debris" conducted in FY2022. The present study aims to construct a monitoring platform for understanding the status inside a reactor during fuel debris removal, and measurement and visualization by sensors moving on the platform. In addition, to develop research personnel through research education by participating in such research projects, classroom lectures, and facility tours is also a goal of this project. In FY2022, each system was improved and expanded toward the final year, and verification experiments were conducted in simulated environments.