Decommissioning report for Wastewater Treatment Facility (Part 2); Chapter on contamination inspection section

Yamamoto, Keisuke; Nakagawa, Takuya; Shimojo, Hiroto; Kijima, Jun; Miura, Daiya; Onose, Yoshihiko*; Namba, Koji*; Uchida, Hiroaki*; Sakamoto, Kazuhiko*; Ono, Chika*; et al.

JAEA-Technology 2024-019, 211 Pages, 2025/02

JAEA-Technology-2024-019.pdf:35.35MB

The uranium enrichment facilities at the Nuclear Fuel Cycle Engineering Laboratories of Japan Atomic Energy Agency (JAEA) were constructed sequentially to develop uranium enrichment technology with centrifugal separation method. The developed technologies were transferred to Japan Nuclear Fuel Limited until 2001. And the original purpose has been achieved. Wastewater Treatment Facility, one of the uranium enrichment facilities, was constructed in 1976 to treat radioactive liquid waste generated at the facilities, and it finished the role in 2008. In accordance with the Medium/Long-Term Management Plan of JAEA Facilities, interior equipment installed in this facility had been dismantled and removed since November 2021 to August 2023. This report summarizes the findings obtained through the work related to the contamination inspection methods cancellation the controlled area of Wastewater Treatment Facility from September 2023 to March 2024.

Physicochemical characterization of the youngest active domain in major fault zones using the weathering index and X-ray computed tomography

Iwamori, Akiyuki*; Ogita, Yasuhiro; Shimada, Koji; Tateishi, Ryo*; Takagi, Hideo*; Ota, Toru*; Cho, T.*; Kudo, Shunsuke*; Nojiri, Keisuke*; Shigemitsu, Yasumune*; et al.

Engineering Geology, 344, p.107821_1 - 107821_20, 2025/01

https://doi.org/10.1016/j.enggeo.2024.107821

Clarification of the physicochemical characterization of brittle fault rocks is important not only for understanding the history of the fault activity and deformation mechanisms, but also for assessing the siting conditions of important facilities such as nuclear power plants, radioactive waste disposal sites, and oil storage bases. Here, we apply the chemical weathering index (W values) to the brittle fault rocks of the Shiraki-Nyu fault (granite), the Tsuruga fault (geological boundary between granite and greenstone), and the Yamada fault (adamellite), which are active faults in the peripheral area of Wakasa Bay, and their respective protoliths (hard rocks), and investigate the physicochemical characteristics of the youngest active domain of brittle fault rocks based on the relationship between computed tomography data (CT numbers) and alteration intensity (AI values). The W values of the fault rocks are mainly affected by changes in NaO and CaO, corresponding to the elution or deposition of plagioclase and calsite for granite, clinopyroxene and hornblende for greenstone, and plagioclase for adamellite. The W values mainly indicate the effects of hydrothermal alteration up to 50 60 percent and of weathering at over 60 percent. On the other hand, the CT values of the fault rocks are lowest in the fault gouge corresponding to the latest active zone, which was identified as the lowest density zone. In addition, fresh plagioclase fragments are present in each fault gouge of the latest active zone of the active faults in this study. The application of W values to brittle fault rocks is an effective method for understanding the trends of mineralogical variations associated with hydrothermal alteration and weathering in fault rocks, and it is highly possible to improve the accuracy of identifying the youngest active domain in major fault zones through joint analyses of CT numbers.

Research plan on geosphere stability for long-term isolation of radioactive waste (Scientific program for fiscal year 2024)

Niwa, Masakazu; Shimada, Akiomi; Asamori, Koichi; Sueoka, Shigeru; Komatsu, Tetsuya; Nakajima, Toru; Ogata, Manabu; Uchida, Mao; Nishiyama, Nariaki; Tanaka, Kiriha; et al.

JAEA-Review 2024-035, 29 Pages, 2024/09

JAEA-Review-2024-035.pdf:1.24MB

This report is a plan of research and development (R&D) on geosphere stability for long-term isolation of high-level radioactive waste (HLW) in Japan Atomic Energy Agency (JAEA), in fiscal year 2024. The objectives and contents of this research are described in detail based on the JAEA 4th Medium- and Long-term Plan (fiscal years 2022-2028). In addition, the background of this research is described from the necessity and the significance for site investigation and safety assessment, and the past progress. The plan framework is structured into the following categories: (1) Development and systematization of investigation techniques, (2) Development of models for long-term estimation and effective assessment, (3) Development of dating techniques.

Estimation of shear wave polarization anisotropy in the fore-arc region of Kyushu, Japan

Ogawa, Hiroki; Hiratsuka, Shinya; Asamori, Koichi; Shimada, Koji; Niwa, Masakazu

Butsuri Tansa, 77, p.15 - 23, 2024/00

https://doi.org/10.3124/segj.77.15

Understanding pathways of volcanic fluids or non-volcanic slab-related fluids by means of investigations from the surface is effective for preventing the loss of the function as a natural barrier in the geological disposal system of high-level radioactive waste. There are few long active faults and is no record of remarkable groundwater discharge in the fore-arc region of Kyushu, Japan. However, previous studies on seismic wave velocity and resistivity structures suggest the existence of the zones of slab-related fluids derived from the Philippine Sea Plate in the crust. To associate pathways of fluids in the fore-arc region of Kyushu with distribution and properties of cracks, we applied a shear wave splitting analysis to waveform data of shallow earthquakes in this region. In the inland part of Kyushu, the orientation of the faster polarized shear wave is subparallel to the axes of the maximum horizontal compressional stress, which can attribute the shear wave polarization anisotropy mainly to the distributions of cracks aligned along the crustal stress. The faster polarized shear wave at the seismic stations in the coastal area of Hyuganada Sea shows the orientation of NNE-SSWNE-SW or NNW-SSENW-SE different from that of the crustal stress. The average intensity of anisotropy over the ray-path length from hypocenters to each seismic station is also calculated. As a result, a few ray paths acquired at the seismic station TAKAZA to the east of Kirishima Volcano show larger anisotropic intensity, 5.6-7.0%. There is no denying the possibility that these ray paths reflect the pathways of the hydrothermal fluids. In the coastal area of Hyuganada Sea, however, it is confirmed that we do not obtain the ray paths that indicate continuous fluid pathways extending from hypocenters to each seismic station because the anisotropic intensity over the ray-path length is less than 5%.

Partial breakdown of translation symmetry at a structural quantum critical point associated with a ferroelectric soft mode

Ishii, Yui*; Yamamoto, Arisa*; Sato, Naoki*; Nambu, Yusuke*; Kawamura, Seiko; Murai, Naoki; Ohara, Koji*; Kawaguchi, Shogo*; Mori, Takao*; Mori, Shigeo*

Physical Review B, 106(13), p.134111_1 - 134111_7, 2022/10

https://doi.org/10.1103/PhysRevB.106.134111

Sodium-cooled Fast Reactors

Ohshima, Hiroyuki; Morishita, Masaki*; Aizawa, Kosuke; Ando, Masanori; Ashida, Takashi; Chikazawa, Yoshitaka; Doda, Norihiro; Enuma, Yasuhiro; Ezure, Toshiki; Fukano, Yoshitaka; et al.

Sodium-cooled Fast Reactors; JSME Series in Thermal and Nuclear Power Generation, Vol.3, 631 Pages, 2022/07

https://shop.elsevier.com/books/sodium-cooled-fast-reactors/morishita/978-0-12-824076-2

This book is a collection of the past experience of design, construction, and operation of two reactors, the latest knowledge and technology for SFR designs, and the future prospects of SFR development in Japan. It is intended to provide the perspective and the relevant knowledge to enable readers to become more familiar with SFR technology.

Hybridization of Bogoliubov quasiparticles between adjacent CuO layers in the triple-layer cuprate BiSrCaCuO studied by angle-resolved photoemission spectroscopy

Ideta, Shinichiro*; Johnston, S.*; Yoshida, Teppei*; Tanaka, Kiyohisa*; Mori, Michiyasu; Anzai, Hiroaki*; Ino, Akihiro*; Arita, Masashi*; Namatame, Hirofumi*; Taniguchi, Masaki*; et al.

Physical Review Letters, 127(21), p.217004_1 - 217004_6, 2021/11

https://doi.org/10.1103/PhysRevLett.127.217004

Annual report for research on geosphere stability for long-term isolation of radioactive waste in fiscal year 2019

Ishimaru, Tsuneari; Ogata, Nobuhisa; Kokubu, Yoko; Shimada, Koji; Hanamuro, Takahiro; Shimada, Akiomi; Niwa, Masakazu; Asamori, Koichi; Watanabe, Takahiro; Sueoka, Shigeru; et al.

JAEA-Research 2020-011, 67 Pages, 2020/10

JAEA-Research-2020-011.pdf:3.87MB

This annual report documents the progress of research and development (R&D) in the 5th fiscal year during the JAEA 3rd Mid- and Long-term Plan (fiscal years 2015-2021) to provide the scientific base for assessing geosphere stability for long-term isolation of the high-level radioactive waste. The planned framework is structured into the following categories: (1) Development and systematization of investigation techniques, (2) Development of models for long-term estimation and effective assessment, (3) Development of dating techniques. The current status of R&D activities with previous scientific and technological progress is summarized.

Research on activation assessment of a reactor structural materials for decommissioning, 2

Seki, Misaki; Ishikawa, Koji*; Sano, Tadafumi*; Nagata, Hiroshi; Otsuka, Kaoru; Omori, Takazumi; Hanakawa, Hiroki; Ide, Hiroshi; Tsuchiya, Kunihiko; Fujihara, Yasuyuki*; et al.

KURNS Progress Report 2019, P. 279, 2020/08

https://www.rri.kyoto-u.ac.jp/PUB/report/PR/ProgRep2019/ProgressReport2019_online.pdf

no abstracts in English

Research plan on geosphere stability for long-term isolation of radioactive waste (Scientific program for fiscal year 2020)

Ishimaru, Tsuneari; Ogata, Nobuhisa; Shimada, Koji; Kokubu, Yoko; Niwa, Masakazu; Asamori, Koichi; Watanabe, Takahiro; Sueoka, Shigeru; Komatsu, Tetsuya; Yokoyama, Tatsunori; et al.

JAEA-Review 2020-010, 46 Pages, 2020/07

JAEA-Review-2020-010.pdf:1.89MB

This report is a plan of research and development (R&D) on geosphere stability for long-term isolation of high-level radioactive waste (HLW) in Japan Atomic Energy Agency (JAEA), in fiscal year 2020. The objectives and contents in fiscal year 2020 are described in detail based on the JAEA 3rd Medium- and Long-term Plan (fiscal years 2015-2021). In addition, the background of this research is described from the necessity and the significance for site investigation and safety assessment, and the past progress. The plan framework is structured into the following categories: (1) Development and systematization of investigation techniques, (2) Development of models for long-term estimation and effective assessment, (3) Development of dating techniques.