Cesium sorption onto alkaline activated materials

Hagiwara, Hiroki; Takaku, Atsushi*; Sagawa, Hiroshi*; Kanno, Futoshi*; Ito, Azusa; Ando, Taichi*; Ichihara, Masatsugu*; Watanabe, Yusuke; Koarai, Kazuma; Kato, Jun; et al.

Proceedings of Waste Management Symposia 2026 (WM2026) (Internet), 7 Pages, 2026/03

Visualisation and quantitative evaluation of chlorides in corroded crevice of stainless steel using radioisotope Cl

Aoki, So; Abe, Yosuke; Abe, Hiroshi*; Watanabe, Yutaka*; Yamamoto, Masahiro*

Corrosion Science, 255, p.113119_1 - 113119_10, 2025/10

https://doi.org/10.1016/j.corsci.2025.113119

This study aimed to visualise the distribution of chloride in the corroded crevice of stainless steel and to evaluate the chloride content quantitatively. Crevice corrosion tests were carried out using Cl, a radioactive isotope of chloride, as a tracer in NaCl test solutions. After crevice corrosion tests, stainless steel specimens were placed on an imaging plate. The imaging plate was sensitised by -ray emitted by Cl adhering to the crevice. As a result, the chloride distribution in the corroded area inside the crevice was visualised. A calibration curve for the amount of Cl was obtained from the relationship between the time of photosensitivity to -ray emitted by Cl and the luminance of the imaging plate. The chloride content in the corroded crevice was quantitatively evaluated based on the calibration curve. These visualisation and quantitative evaluation methods were also applied to tests in which specimens were left in pure water after crevice corrosion tests, and the behaviour of chloride in crevice corrosion was discussed.

Start-up of a test equipment for corrosion evaluation using copper thin film

Suganuma, Kazuaki; Sekiyama, Yoshio*; Honda, Tomoyuki*; Dei, Tatsumi; Suzuki, Katsuo; Fujirai, Kosuke; Suzuki, Hiroshi*; Nakata, Morihiro*; Hosokawa, Hideaki*; Watanabe, Yasuhiro; et al.

Proceedings of 21st Annual Meeting of Particle Accelerator Society of Japan (Internet), p.738 - 740, 2024/10

https://www.pasj.jp/web_publish/pasj2024/proceedings/PDF/THP0/THP061.pdf

In the J-PARC accelerator, the inner surface of the copper tubes that make up most of the coolant pipes is corroded. Generally, additives are added to the coolant to prevent corrosion, but the accelerator is in a radiation environment and additives cannot be used in the coolant to avoid impurities in the coolant become polluted by radiation. For example, in materials research in the nuclear field, there is a lot of research on strong acidic or strong alkaline solutions and corrosion resistant materials, but there is little literature on corrosion protection studies of purified water and copper materials. In general, we believe this is because the use of purified water and copper together in a radiation environment is limited. Corrosion testing of purified water and copper materials is unique to accelerators. The use of a thin copper film was considered as a possible method. In this case, we report on the current status of a new initiative, testing with copper thin films.

Recent status of the cryogenic sample environment at the MLF, J-PARC

Ishikado, Motoyuki*; Takahashi, Ryuta*; Yamauchi, Yasuhiro*; Nakamura, Masatoshi*; Ishimaru, Sora*; Yamauchi, Sara*; Kawamura, Seiko; Kira, Hiroshi*; Sakaguchi, Yoshifumi*; Watanabe, Masao; et al.

JPS Conference Proceedings (Internet), 41, p.011010_1 - 011010_7, 2024/05

https://doi.org/10.7566/JPSCP.41.011010

Neutron production in the interaction of 200-MeV deuterons with Li, Be, C, Al, Cu, Nb, In, Ta, and Au

Watanabe, Yukinobu*; Sadamatsu, Hiroki*; Araki, Shohei; Nakano, Keita; Kawase, Shoichiro*; Kin, Tadahiro*; Iwamoto, Yosuke; Satoh, Daiki; Hagiwara, Masayuki*; Yashima, Hiroshi*; et al.

EPJ Web of Conferences, 284, p.01041_1 - 01041_4, 2023/05

https://doi.org/10.1051/epjconf/202328401041

Intensive fast neutron sources using deuteron accelerators have been proposed for the study of medical RI production, radiation damage for fusion reactor materials, nuclear transmutation of radioactive waste, and so on. Neutron production data from various materials bombarded by deuterons are required for the design of such neutron sources. In the present work, we have conducted a systematic measurement of double-differential neutron production cross sections (DDXs) for a wide atomic number range of targets (Li, Be, C, Al, Cu, Nb, In, Ta, and Au) at an incident energy of 200 MeV in the Research Center for Nuclear Physics (RCNP), Osaka University. A deuteron beam accelerated to 200 MeV was transported to the neutron experimental hall and focused on a thin target foil. Emitted neutrons from the target were detected by two different-size EJ301 liquid organic scintillators located at two distances of 7 m and 20 m, respectively. The neutron DDXs were measured at six angles from 0 to 25). The neutron energy was determined by a conventional time-of-flight (TOF) method. The measured DDXs were compared with theoretical model calculations by the DEUteron-induced Reaction Analysis Code System (DEURACS) and PHITS. The result indicated that the DEURACS calculation provides better agreement with the measured DDXs than the PHITS calculation.

A Safer preprocessing system for analyzing dissolved organic radiocarbon in seawater

Otosaka, Shigeyoshi*; Jeon, H.*; Hou, Y.*; Watanabe, Takahiro; Aze, Takahiro*; Miyairi, Yosuke*; Yokoyama, Yusuke*; Ogawa, Hiroshi*

Nuclear Instruments and Methods in Physics Research B, 527, p.1 - 6, 2022/09

https://doi.org/10.1016/j.nimb.2022.07.003

The measurement the radiocarbon of dissolved organic matter (DOC) in seawater can provide information about a timescale of the dynamics of dissolved organic matter as well as about its sources in the ocean. Due to the low DOC concentration in seawater, in spite of the development of accelerator mass spectrometry, a relatively large volume of seawater (1 L) is required for that analysis. In addition, complicated processing such as UV irradiation that emits high heat is required. In this study, we have developed a safer and easier method to analyze DOC in seawater than the conventional method. A particularly significant change was the adoption of a low-pressure mercury lamp in the decomposition system, which enabled direct decomposition of organic matter at lower temperatures. We also propose a method to quantitatively evaluate the accuracy of this system by analyzing simulated seawater consists of a soluble reference material of organic matter and sodium chloride. This method is expected to be applied not only to carbon isotope ratio analysis but also to analysis of trace elements and isotopes of various dissolved organic substances.

Ground-state -decay spectroscopy of Ta

Mukai, Momo*; Hirayama, Yoshikazu*; Watanabe, Yutaka*; Watanabe, Hiroshi*; Koura, Hiroyuki; Jeong, S. C.*; Miyatake, Hiroari*; Brunet, M.*; Ishizawa, Satoshi*; Kondev, F. G.*; et al.

Physical Review C, 105(3), p.034331_1 - 034331_6, 2022/03

https://doi.org/10.1103/PhysRevC.105.034331

Thermally altered subsurface material of asteroid (162173) Ryugu

Kitazato, Kohei*; Milliken, R. E.*; Iwata, Takahiro*; Abe, Masanao*; Otake, Makiko*; Matsuura, Shuji*; Takagi, Yasuhiko*; Nakamura, Tomoki*; Hiroi, Takahiro*; Matsuoka, Moe*; et al.

Nature Astronomy (Internet), 5(3), p.246 - 250, 2021/03

https://doi.org/10.1038/s41550-020-01271-2

Here we report observations of Ryugu's subsurface material by the Near-Infrared Spectrometer (NIRS3) on the Hayabusa2 spacecraft. Reflectance spectra of excavated material exhibit a hydroxyl (OH) absorption feature that is slightly stronger and peak-shifted compared with that observed for the surface, indicating that space weathering and/or radiative heating have caused subtle spectral changes in the uppermost surface. However, the strength and shape of the OH feature still suggests that the subsurface material experienced heating above 300 C, similar to the surface. In contrast, thermophysical modeling indicates that radiative heating does not increase the temperature above 200 C at the estimated excavation depth of 1 m, even if the semimajor axis is reduced to 0.344 au. This supports the hypothesis that primary thermal alteration occurred due to radiogenic and/or impact heating on Ryugu's parent body.

Status of study of long-term assessment of transport of radioactive contaminants in the environment of Fukushima (FY2018) (Translated document)

Nagao, Fumiya; Niizato, Tadafumi; Sasaki, Yoshito; Ito, Satomi; Watanabe, Takayoshi; Dohi, Terumi; Nakanishi, Takahiro; Sakuma, Kazuyuki; Hagiwara, Hiroki; Funaki, Hironori; et al.

JAEA-Research 2020-007, 249 Pages, 2020/10

JAEA-Research-2020-007.pdf:15.83MB

The accident of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. occurred due to the Great East Japan Earthquake, Sanriku offshore earthquake, of 9.0 magnitude and the accompanying tsunami. As a result, large amount of radioactive materials was released into the environment. Under these circumstances, Japan Atomic Energy Agency (JAEA) has been conducting "Long-term Assessment of Transport of Radioactive Contaminants in the Environment of Fukushima" concerning radioactive materials released in environment, especially migration behavior of radioactive cesium since November 2012. This report is a summary of the research results that have been obtained in environmental dynamics research conducted by JAEA in Fukushima Prefecture.

Vertical and horizontal distributions of Cs on paved surfaces affected by the Fukushima Dai-ichi Nuclear Power Plant accident

Yoshimura, Kazuya; Watanabe, Takayoshi; Kurikami, Hiroshi

Journal of Environmental Radioactivity, 217, p.106213_1 - 106213_6, 2020/06

https://doi.org/10.1016/j.jenvrad.2020.106213