Annual report for research on geosphere stability for long-term isolation of radioactive waste in fiscal year 2024

Asamori, Koichi; Sueoka, Shigeru; Kobayashi, Tomoharu; Nishiyama, Nariaki; Tanaka, Kiriha; Murakami, Osamu; Fukuda, Shoma; Ogata, Manabu; Uchida, Mao; Komatsu, Tetsuya; et al.

JAEA-Research 2025-007, 99 Pages, 2025/10

JAEA-Research-2025-007.pdf:12.36MB

This annual report documents the progress of research and development (R&D) in the 3rd fiscal year of the JAEA 4th Medium- and Long-term Plan (fiscal years 2022-2028) to provide the scientific base for assessing geosphere stability for long-term isolation of high-level radioactive waste. 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. The current status of R&D activities with previous scientific and technological progress is summarized.

Update of MPS modules for J-PARC Linac and RCS

Takahashi, Hiroki; Hayashi, Naoki; Nishiyama, Koichi*; Suzuki, Takahiro*; Ishiyama, Tatsuya*

Proceedings of 16th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.271 - 274, 2019/07

https://www.pasj.jp/web_publish/pasj2019/proceedings/index_abstracts.html

In the event of an abnormal situation, a machine protection system (MPS) that immediately inhibits the beam is indispensable to minimize the damage and the radioactivation by beam loss. The existing MPS was developed during the construction period of the J-PARC. Then, the system has been working stably for more than ten years. On the other hand, since there are many MPS modules that have been used from the beginning of J-PARC operation, it is important to systematically proceed with updating (replacement) of modules as a measure against aging of MPS. However, the main components of the existing MPS module have been discontinued. Therefore, it is indispensable to redesign the MPS modules in consideration of improvement such as the compatibility with existing modules and the miniaturization. In this paper, the development status of the new module and the update plan of MPS for Linac and RCS are detailed.

New muonium HFS measurements at J-PARC/MUSE

Strasser, P.*; Aoki, Masaharu*; Fukao, Yoshinori*; Higashi, Yoshitaka*; Higuchi, Takashi*; Iinuma, Hiromi*; Ikedo, Yutaka*; Ishida, Katsuhiko*; Ito, Takashi; Iwasaki, Masahiko*; et al.

Hyperfine Interactions, 237(1), p.124_1 - 124_9, 2016/12

https://doi.org/10.1007/s10751-016-1331-4

Tuning of ultra-slow muon transport system

Adachi, Taihei*; Ikedo, Yutaka*; Nishiyama, Kusuo*; Yabuuchi, Atsushi*; Nagatomo, Takashi*; Strasser, P.*; Ito, Takashi; Higemoto, Wataru; Kojima, Kenji*; Makimura, Shunsuke*; et al.

JPS Conference Proceedings (Internet), 8, p.036017_1 - 036017_4, 2015/09

https://doi.org/10.7566/JPSCP.8.036017

JT-60SA assembly and metrology

Suzuki, Sadaaki; Yagyu, Junichi; Masaki, Kei; Nishiyama, Tomokazu; Nakamura, Shigetoshi; Saeki, Hisashi; Hoshi, Ryo; Sawai, Hiroaki; Hasegawa, Koichi; Arai, Takashi; et al.

NIFS-MEMO-67, p.266 - 271, 2014/02

no abstracts in English

Study of system safety evaluation on LTO of national project; Structural integrity assessment of reactor pressure vessels

Onizawa, Kunio; Masaki, Koichi; Osakabe, Kazuya*; Nishikawa, Hiroyuki*; Katsuyama, Jinya; Nishiyama, Yutaka

Nihon Hozen Gakkai Dai-9-Kai Gakujutsu Koenkai Yoshishu, p.374 - 379, 2012/07

To assure the structural integrity of a reactor pressure vessel (RPV) is known as one of the critical issues to maintain the safe long-term operation of a nuclear power plant. In Japan, the assessment methods for RPV integrity, stipulated in the codes and standards, have been endorsed by the regulatory body. Authors have initiated extensive research on the improvement of structural integrity assessment methods of RPVs. In this paper, we describe some research results obtained from the first-year activity. These include the study on revisiting the technical background of the methods, such as loading conditions, postulated crack definition, the other evaluation methods. In addition, studies on probabilistic methods for the applicability to the current rules and the standardization of the probabilistic analysis methods have been presented.

J-PARC decay muon channel construction status

Strasser, P.*; Shimomura, Koichiro*; Koda, Akihiro*; Kawamura, Naritoshi*; Fujimori, Hiroshi*; Makimura, Shunsuke*; Kobayashi, Yasuo*; Nakahara, Kazutaka*; Kato, Mineo*; Takeshita, Soshi*; et al.

Journal of Physics; Conference Series, 225, p.012050_1 - 012050_8, 2010/06

https://doi.org/10.1088/1742-6596/225/1/012050

JAEA-ASRC muon research at J-PARC MUSE

Higemoto, Wataru; Ito, Takashi; Ninomiya, Kazuhiko; Heffner, R.*; Shimomura, Koichiro*; Nishiyama, Kusuo*; Miyake, Yasuhiro*

Journal of Physics; Conference Series, 225, p.012012_1 - 012012_4, 2010/06

https://doi.org/10.1088/1742-6596/225/1/012012

The Japan Atomic Energy Agency (JAEA)-Advanced Science Research Center (ASRC) has developed experimental equipment at the J-PARC MLF muon science facility (MUSE) for muon spin rotation/relaxation experiments. We have extracted part of the muonbeam into a muon spectrometer constructed downstream from the Decay/Surface muon beam line. The current status of our project is discussed here.

JAEA-ASRC SR project at J-PARC MUSE

Higemoto, Wataru; Heffner, R. H.; Shimomura, Koichiro*; Nishiyama, Kusuo*; Miyake, Yasuhiro*

Nuclear Instruments and Methods in Physics Research A, 600(1), p.182 - 184, 2009/02

https://doi.org/10.1016/j.nima.2008.11.027

At the J-PARC MLF muon science facility (MUSE), JAEA-ASRC is advancing the "SR project". In this project, the muon beam extraction part and the spectrometer will be installed to the downstream of the Decay/Surface muon beam line as a branch of the beam line. ASRC beam line is preparing for a muon spin rotation and relaxation (SR) experiment. Mainly, a positive surface muon beam (29MeV/c) will be used for the experiment. One of the main subject of the ASRC SR project is study of strongly correlated electron systems, especially f-electron systems. By using intense muon beam of MUSE, new insights for f-electron physics will be obtained.

SR in two-dimensional hydrogen bonding system squaric acid

Nishiyama, Kusuo*; Nishiyama, Sumie*; Shimomura, Koichiro*; Kubo, Kenya*; Maruta, Goro*; Higemoto, Wataru

Physica B; Condensed Matter, 374-375, p.433 - 436, 2006/03

https://doi.org/10.1016/j.physb.2005.11.125

Squaric acid, a famous two-dimensional hydrogen-bonded system was studied by SR. From the temperature dependence of the muon spin relaxation rate as well as from the crystal axis dependences, different muon sites at low temperature and at high temperature were found. The nuclear dipole field was calculated for possible muon sites. At low temperature the muon attaches acceptor oxygen, while at 300 K the muon occupies the regular hydrogen sites.