Crystallization processes of quartz in a granitic magma; Implications for the magma chamber processes of Okueyama granite, Kyushu, Japan

Yuguchi, Takashi*; Kato, Takenori*; Ogita, Yasuhiro; Watanabe, Minori*; Yamazaki, Hayato*; Kato, Asuka*; Ito, Daichi*; Yokoyama, Tatsunori; Sakata, Shuhei*; Ono, Takeshi*

Journal of Asian Earth Sciences, 265, p.106091_1 - 106091_13, 2024/04

https://doi.org/10.1016/j.jseaes.2024.106091

Case study activities for nuclear security culture development in JAEA

Amano, Tsukasa; Shibata, Ryodai; Sato, Yoshiharu; Yamazaki, Katsuyuki; Shiromo, Hideo; Nakamura, Hironobu

Proceedings of INMM & ESARDA Joint Annual Meeting 2023 (Internet), 6 Pages, 2023/05

In Japan, about 10 years have passed since the law obligated nuclear operators to develop and maintain a nuclear security culture. During this period, the global nuclear situation has changed significantly, and it is becoming important to maintain a stance that emphasizes compliance with regulations and nuclear security culture. In JAEA, the policy of legal compliance and developing nuclear security culture is determined by the president of JAEA. For legal compliance and developing nuclear security culture, many activities are carried out based on that policy. Finally, these activities are evaluated and improved it every year. Case study is the one of activities that can obtain skills for legal compliance and developing nuclear security culture, such as sensitivity of nuclear security risks, correct understanding of the laws. The procedure for the case study was created with reference to a method called KY-Training which is often applied to safety training program in Japan. KY-Training is a training that participants (groups) can reach the conclusion how to respond to cases through four questions. Firstly, participants are given illustrations and descriptions which has potential of nuclear security risks. Then, participants make discussion according to four questions. Consequently, participants can effectively become aware of nuclear security risks. In the 2022 case study, we prepared 23 cases so that they can select choose freely according to role of participants such as in charge of nuclear security, guards, general employees. Finally, participants are asked to fill a questionnaire to evaluate effectiveness of case study. The result of questionnaires indicated that the case study was able to lead to improvement sensitivity of nuclear security risks and correct understanding of the laws. Overall, case study results suggested that JAEA's efforts were implying sufficiently to develop and maintain a nuclear security culture.

Efforts of procurement and quality managements for physical protection system in JAEA

Shibata, Ryodai; Yamazaki, Katsuyuki; Yamada, Hiroyuki; Miyaji, Noriko; Nakamura, Hironobu

Dai-42-Kai Nihon Kaku Busshitsu Kanri Gakkai Nenji Taikai Kaigi Rombunshu (Internet), 4 Pages, 2021/11

Physical protection systems (PPS) operated for security in nuclear facilities uses computer-controlled systems. If malicious peoples change program or install computer virus to PPS, they are invalidated. Due to insufficient surveillance etc., and then unauthorized removal and sabotage may be caused. This paper introduces efforts of necessary procurement and quality managements etc., for decreasing there affect, and their details.

Improvement in sputtering rate uniformity over large deposition area of large-scale ion beam sputtering system

Maruyama, Ryuji; Yamazaki, Dai; Akutsu, Kazuhiro*; Hanashima, Takayasu*; Miyata, Noboru*; Aoki, Hiroyuki; Soyama, Kazuhiko

JPS Conference Proceedings (Internet), 33, p.011092_1 - 011092_6, 2021/03

https://doi.org/10.7566/JPSCP.33.011092

no abstracts in English

New precise measurements of muonium hyperfine structure at J-PARC MUSE

Strasser, P.*; Abe, Mitsushi*; Aoki, Masaharu*; Choi, S.*; Fukao, Yoshinori*; Higashi, Yoshitaka*; Higuchi, Takashi*; Iinuma, Hiromi*; Ikedo, Yutaka*; Ishida, Katsuhiko*; et al.

EPJ Web of Conferences, 198, p.00003_1 - 00003_8, 2019/01

https://doi.org/10.1051/epjconf/201919800003

Development of high-polarization Fe/Ge neutron polarizing supermirror; Possibility of fine-tuning of scattering length density in ion beam sputtering

Maruyama, Ryuji; Yamazaki, Dai; Akutsu, Kazuhiro*; Hanashima, Takayasu*; Miyata, Noboru*; Aoki, Hiroyuki; Takeda, Masayasu; Soyama, Kazuhiko

Nuclear Instruments and Methods in Physics Research A, 888, p.70 - 78, 2018/04

https://doi.org/10.1016/j.nima.2018.01.068

The multilayer structure of Fe/Si and Fe/Ge systems fabricated by ion beam sputtering (IBS) was investigated using X-ray and polarized neutron reflectivity measurements and scanning transmission electron microscopy with energy-dispersive X-ray analysis. The obtained result revealed that the incorporation of sputtering gas particles (Ar) in the Ge layer gives rise to a marked reduction in the neutron scattering length density (SLD) and contributes to the SLD contrast between the Fe and Ge layers almost vanishing for spin-down neutrons. This leads to a possibility of fine-tuning of the SLD for the IBS, which is required to realize a high polarization efficiency of a neutron polarizing supermirror. Fe/Ge polarizing supermirror with fabricated showed a spin-up reflectivity of 0.70 at the critical momentum transfer. The polarization was higher than 0.985 for the range where the correction for the polarization inefficiencies of the beamline works properly.

Materials and Life Science Experimental Facility at the Japan Proton Accelerator Research Complex, 3; Neutron devices and computational and sample environments

Sakasai, Kaoru; Sato, Setsuo*; Seya, Tomohiro*; Nakamura, Tatsuya; To, Kentaro; Yamagishi, Hideshi*; Soyama, Kazuhiko; Yamazaki, Dai; Maruyama, Ryuji; Oku, Takayuki; et al.

Quantum Beam Science (Internet), 1(2), p.10_1 - 10_35, 2017/09

https://doi.org/10.3390/qubs1020010

Neutron devices such as neutron detectors, optical devices including supermirror devices and He neutron spin filters, and choppers are successfully developed and installed at the Materials Life Science Facility (MLF) of the Japan Proton Accelerator Research Complex (J-PARC), Tokai, Japan. Four software components of MLF computational environment, instrument control, data acquisition, data analysis, and a database, have been developed and equipped at MLF. MLF also provides a wide variety of sample environment options including high and low temperatures, high magnetic fields, and high pressures. This paper describes the current status of neutron devices, computational and sample environments at MLF.

Silver photo-diffusion and photo-induced macroscopic surface deformation of GeS/Ag/Si substrate

Sakaguchi, Yoshifumi*; Asaoka, Hidehito; Uozumi, Yuki; Kondo, Keietsu; Yamazaki, Dai; Soyama, Kazuhiko; Ailavajhala, M.*; Mitkova, M.*

Journal of Applied Physics, 120(5), p.055103_1 - 055103_10, 2016/08

https://doi.org/10.1063/1.4959207

Improvement of exchanging method of neutron startup source of high temperature engineering test reactor

Sawahata, Hiroaki; Shimazaki, Yosuke; Ishitsuka, Etsuo; Yamazaki, Kazunori; Yanagida, Yoshinori; Fujiwara, Yusuke; Takada, Shoji; Shinozaki, Masayuki; Hamamoto, Shimpei; Tochio, Daisuke

Proceedings of 24th International Conference on Nuclear Engineering (ICONE-24) (DVD-ROM), 8 Pages, 2016/06

https://doi.org/10.1115/ICONE24-60842

In the HTTR, Cf is loaded in the reactor core as a neutron startup source and changed at frequency. In this exchange work, there were two technical issues; slightly higher radiation exposure of workers by neutron leakage and reliability of neutron source transportation container in handling. To reduce the radiation dose by neutron leakage, detail numerical evaluations using PHITS code were carried out, the effective shielding method for fuel handling machine was proposed. Easily removable polyethylene blocks and particles were used as the neutron shielding, and installed in the cooling paths of the fuel handling machine. As a result, the collective effective dose by neutron was reduced from about 700 man-microSv to about 300 man-microSv. As to the neutron source transportation container, the handling performance was improved and the handling work was safety accomplished by downsizing.

Experiments of coolant accumulation in SG U tube and analytical model development

Yamaji, Tatsuya*; Koizumi, Yasuo; Yamazaki, Kohei*; Otake, Hiroyasu*; Hasegawa, Koji*; Onuki, Akira*; Kanamori, Daisuke*

Konsoryu Shimpojiumu 2015 Koen Rombunshu (USB Flash Drive), 2 Pages, 2015/08

Experiments of condensing counter-current two-phase flow in a vertical pipe were performed. This study was intended to examine water accumulation in the up-flow side of steam generator U-tubes of a PWR during the reflux cooling stage of a small break LOCA. It has been apprehended that the water accumulation may result in temporary core liquid level depression. The inner diameter and the length of a test flow channel used in the experiments were 18 mm and 4 m, respectively. The experiments were performed by using steam and water at 0.1 MPa. Two kinds of experiments were conducted; visualization experiments by using a transparent test section and quantitative water accumulation evaluation experiments by using a brass test section. Even if water on the inner surface of the test pipe could not flow downward at the lower portion of the test pipe, a part of water became to flow downward at the upper portion of the test pipe since steam velocity decreased because of condensation. Thus, two-phase mixture level was formed in the upper portion of the test pipe, which resulted in the water accumulation in the pipe. The model to predict the water accumulation was proposed. It predicted the water accumulation reasonably well.