One-dimensional band structure in quasi-two-dimensional -MoO revealed by angle-resolved photoelectron spectroscopy and first-principles calculation

Sumida, Kazuki; Higaki, Sota*; Sato, Hitoshi*; Tsuru, Daichi*; Miyamoto, Koji*; Okuda, Taichi*; Kuroiwa, Yoshihiro*; Moriyoshi, Chikako*; Takase, Koichi*; Oguchi, Tamio*; et al.

Journal of the Physical Society of Japan, 92(8), p.084706_1 - 084706_6, 2023/08

https://doi.org/10.7566/JPSJ.92.084706

Space weather benchmarks on Japanese society

Ishii, Mamoru*; Shiota, Daiko*; Tao, Chihiro*; Ebihara, Yusuke*; Fujiwara, Hitoshi*; Ishii, Takako*; Ichimoto, Kiyoshi*; Kataoka, Ryuho*; Koga, Kiyokazu*; Kubo, Yuki*; et al.

Earth, Planets and Space (Internet), 73(1), p.108_1 - 108_20, 2021/12

https://doi.org/10.1186/s40623-021-01420-5

We surveyed the relationship between the scale of space weather events and their occurrence rate in Japan and we discussed the social impact of these phenomena during the Project for Solar-Terrestrial Environment Prediction (PSTEP). The information was compiled for domestic users of space weather forecasts for appropriate preparedness against space weather disasters. This paper gives a comprehensive summary of the survey, focusing on the fields of electricity, satellite operations, communication and broadcasting, satellite positioning usage, aviation, human space activity, and daily life on the Earth's surface, using the cutting-edge knowledge of space weather. Quantitative estimations of the economic impact of space weather events on electricity and aviation are also given.

Annual report on the environmental radiation monitoring around the Tokai Reprocessing Plant FY2018

Nakano, Masanao; Fujii, Tomoko; Nemoto, Masashi; Tobita, Keiji; Kono, Takahiko; Hosomi, Kenji; Nishimura, Shusaku; Matsubara, Natsumi; Maehara, Yushi; Narita, Ryosuke; et al.

JAEA-Review 2019-048, 165 Pages, 2020/03

JAEA-Review-2019-048.pdf:2.69MB

Environmental radiation monitoring around the Tokai Reprocessing Plant has been performed by the Nuclear Fuel Cycle Engineering Laboratories, based on "Safety Regulations for the Reprocessing Plant of Japan Atomic Energy Agency, Chapter IV - Environmental Monitoring". This annual report presents the results of the environmental monitoring and the dose estimation to the hypothetical inhabitant due to the radioactivity discharged from the plant to the atmosphere and the sea during April 2018 to March 2019. In this report, some data include the influence of the accidental release from the Fukushima Daiichi Nuclear Power Station of Tokyo Electric Power Co., Inc. (the trade name was changed to Tokyo Electric Power Company Holdings, Inc. on April 1, 2016) in March 2011. Appendices present comprehensive information, such as monitoring programs, monitoring methods, monitoring results and their trends, meteorological data and discharged radioactive wastes. In addition, the data which were influenced by the accidental release and exceeded the normal range of fluctuation in the monitoring, were evaluated.

Study on characterization of colloidal silica grout for rock excavation under saline groundwater

Tsuji, Masakuni*; Nakashima, Hitoshi*; Saito, Akira*; Okihara, Mitsunobu*; Sato, Toshinori

45th Annual Waste Management Conference (WM 2019); Encouraging Young Men & Women to Achieve Their Goals in Radwaste Management, Vol.7, p.4749 - 4763, 2020/01

A rock excavation grouting technology has been recently studied as significant technology for reducing the ingress of water into the deep repository. However, it has not been studied for applying to the coastal region, where it is discussed to be a more suitable region for the geological disposal in Japan. The latest material called colloidal silica grout (CSG) is good for sealing narrow fractures but is known to be sensitive to the salinity of groundwater because of its gelling property with salt accelerator. Although the gelling of CSG can be controlled by adding an acidic pH adjuster, the methodology for delivering the appropriate grout is not well established for such conditions of saline groundwater. Therefore, this research project was established to enhance the existing rock grouting technology for deep repositories.

Characterisation of colloidal silica grout under saline groundwater; Overall results for 3-year research project

Tsuji, Masakuni*; Aoyagi, Kazuhei; Nakashima, Hitoshi*; Okihara, Mitsunobu*; Sato, Toshinori

Proceedings of the Nordic Grouting Symposium 2019 (Internet), 15 Pages, 2019/09

This paper shows an overall result of the 3-year study on the characterisation of the colloidal silica grout (CSG) under saline groundwater, aiming to enhance the existing rock grouting technology, especially for the CSG under the saline groundwater. As a first step, we performed the survey of the latest grouting technology of CSG. We developed a feasible mixing methodology and have obtained the various CSG's properties impacted by the salty mixing water or submerged by saline water. Moreover, we proposed a theory for the grout penetration under saline water and performed the injection tests. In the second workshop in the final year, our overall findings in this study were recognised to attain some progress in the development of the grouting technology.

Gamma-ray spectroscopy of single -hypernuclei at J-PARC; Results and perspective

Koike, Takeshi*; Hasegawa, Shoichi; Hayakawa, Shuhei*; Hosomi, Kenji; Ichikawa, Yudai; Imai, Kenichi; Sako, Hiroyuki; Sato, Susumu; Sugimura, Hitoshi; Tamura, Hirokazu; et al.

AIP Conference Proceedings 2130, p.020011_1 - 020011_9, 2019/07

https://doi.org/10.1063/1.5118379

Safe and rapid development of capillary electrophoresis for ultratrace uranyl ions in radioactive samples by way of fluorescent probe selection for actinide ions from a chemical library

Haraga, Tomoko; Ouchi, Kazuki; Sato, Yoshiyuki; Hoshino, Hitoshi*; Tanana, Rei*; Fujihara, Takashi*; Kurokawa, Hideki*; Shibukawa, Masami*; Ishimori, Kenichiro; Kameo, Yutaka; et al.

Analytica Chimica Acta, 1032, p.188 - 196, 2018/11

https://doi.org/10.1016/j.aca.2018.05.077

The development of safe, rapid and highly sensitive analytical methods for radioactive samples, especially actinide (An) ions, represents an important challenge. Here we propose a methodology for selecting appropriate emissive probes for An ions with very low consumption and emission of radioactivity by capillary electrophoresis-laser-induced fluorescence detection (CE-LIF), using a small chemical library of probes with eight different chelating moieties. It was found that the emissive probe, which possesses the tetradentate chelating moiety, was suitable for detecting uranyl ions. The detection limit for the uranyl-probe complex using CE-LIF combined with dynamic ternary complexation and on-capillary concentration techniques was determined to be 0.7 ppt. This method was successfully applied to real radioactive liquid samples collected from nuclear facilities.

Preheat effect on titanium plate fabricated by sputter-free selective laser melting in vacuum

Sato, Yuji*; Tsukamoto, Masahiro*; Shobu, Takahisa; Yamashita, Yoshihiro*; Yamagata, Shuto*; Nishi, Takaya*; Higashino, Ritsuko*; Okubo, Tomomasa*; Nakano, Hitoshi*; Abe, Nobuyuki*

Applied Physics A, 124(4), p.288_1 - 288_6, 2018/04

https://doi.org/10.1007/s00339-018-1712-4

The dynamics of titanium (Ti) melted by laser irradiation was investigated in a synchrotron radiation experiment. As an indicator of wettability, the contact angle between a selective laser melting (SLM) baseplate and the molten Ti was measured by synchrotron X-rays at 30 keV during laser irradiation. As the baseplate temperature increased, the contact angle decreased, down to 28 degrees at a baseplate temperature of 500C. Based on this result, the influence of wettability of a Ti plate fabricated by SLM in a vacuum was investigated. It was revealed that the improvement of wettability by preheating suppressed sputtering generation, and a surface having a small surface roughness was fabricated by SLM in a vacuum.

Study on characterisation of colloidal silica grout under condition of sea water

Toguri, Satohito*; Okihara, Mitsunobu*; Tsuji, Masakuni*; Nakashima, Hitoshi*; Sugiyama, Hirokazu*; Saito, Akira*; Sato, Toshinori; Aoyagi, Kazuhei; Masunaga, Kosuke

JAEA-Research 2017-013, 131 Pages, 2018/02

JAEA-Research-2017-013.pdf:8.49MB

The discussions on scientifically promising site for the geological disposal has been made at the council of studying group on techniques for geological disposal of radioactive wastes, which is held by Resources and Energy Agency. From the aspect of ensuring safety during the transportation of disposal waste, the coastal area is discussed to be a more suitable area. This report shows the result of the first year of this project as following items; Study on the state-of-art technology and remain tasks; laboratory tests on characterization of colloidal silica grout under sea water; Study on the development of grouting technology (design and the evaluation method of influence on the rock mass).

Latest rock grouting technologies under sea water in Nordic countries and Japan

Tsuji, Masakuni*; Okihara, Mitsunobu*; Nakashima, Hitoshi*; Sato, Toshinori; Aoyagi, Kazuhei

Proceedings of 6th East Asia Forum on Radwaste Management Conference (EAFORM 2017) (Internet), 6 Pages, 2017/12

Regarding the engineering technology, the rock grouting has been recently studied as one of the most important technologies. Although the cement grout has not been reported to be affected by the sea water, the latest grouting material called colloidal silica grout is known to be sensitive to the saline water. The mechanism of its affection by sea water is not clear and its grouting methodology in such condition is not yet established either. Therefore, we studied on the latest grouting technologies for geological disposal in Nordic countries and Japan by article survey and a grouting workshop. As a result, it was found that the approach for countermeasures in grouting under sea water is different between Japan, Sweden, and Finland, which are based respectively on the mixture, on the design method, and on the controlling method. It seems that the best solution against this problem is to establish a hybrid and optimal grouting methodology under sea water by combining each country's developed grouting technology in the near future for saline condition, which is respectively based on mixing, design, and controlling method.