Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
-ray beam measurementsOmer, M.; Shizuma, Toshiyuki*; Koizumi, Mitsuo; Taira, Yoshitaka*; Zen, H.*; Ogaki, Hideaki*; Hajima, Ryoichi*
Radiation Physics and Chemistry, 240, p.113467_1 - 113467_8, 2026/03
Times Cited Count：0 Percentile：0.00(Chemistry, Physical)Kato, Yuya; Kimura, Takashi
Dai-46-Kai Nihon Kaku Busshitsu Kanri Gakkai Nenji Taikai Kaigi Rombunshu (Internet), 3 Pages, 2025/12
no abstracts in English
Tazaki, Makiko; Kimura, Takashi
Dai-46-Kai Nihon Kaku Busshitsu Kanri Gakkai Nenji Taikai Kaigi Rombunshu (Internet), 4 Pages, 2025/12
no abstracts in English
Rossi, F.; Lee, J.; Yoshimi, Yuki*; Shiba, Tomooki; Terada, Kazushi*; Hori, Junichi*
Dai-46-Kai Nihon Kaku Busshitsu Kanri Gakkai Nenji Taikai Kaigi Rombunshu (Internet), 4 Pages, 2025/12
Hanawa, Kazutaka; Hirata, Tomohiro; Shibata, Ryodai; Yamada, Hiroyuki; Miyaji, Noriko
Dai-46-Kai Nihon Kaku Busshitsu Kanri Gakkai Nenji Taikai Kaigi Rombunshu (Internet), 4 Pages, 2025/12
no abstracts in English
Hasegawa, Rie; Nozaki, Teo; Maruyama, Hajime; Miyaji, Noriko
Dai-46-Kai Nihon Kaku Busshitsu Kanri Gakkai Nenji Taikai Kaigi Rombunshu (Internet), 4 Pages, 2025/12
no abstracts in English
Shirafuji, Masaya; Sano, Kyohei; Horiuchi, Masakazu; Kato, Akane; Watanabe, Kazuki; Tanigawa, Masafumi; Maruyama, Hajime; Kitao, Takahiko; Conner, J.*; LaFleur, A.*; et al.
Dai-46-Kai Nihon Kaku Busshitsu Kanri Gakkai Nenji Taikai Kaigi Rombunshu (Internet), 4 Pages, 2025/12
Hirata, Tomohiro; Hanawa, Kazutaka; Shibata, Ryodai; Yamada, Hiroyuki; Yamazaki, Katsuyuki
Dai-46-Kai Nihon Kaku Busshitsu Kanri Gakkai Nenji Taikai Kaigi Rombunshu (Internet), 4 Pages, 2025/12
no abstracts in English
Imamura, Yuri
Dai-46-Kai Nihon Kaku Busshitsu Kanri Gakkai Nenji Taikai Kaigi Rombunshu (Internet), 4 Pages, 2025/12
no abstracts in English
Rossi, F.; Lee, J.; Yoshimi, Yuki*; Hironaka, Kota; Koizumi, Mitsuo; Shiba, Tomooki; Terada, Kazushi*; Hori, Junichi*
ESARDA Bulletin (Internet), 67, p.59 - 67, 2025/12
Koizumi, Mitsuo; Yogo, Akifumi*
Isotope News, (802), p.11 - 14, 2025/12
no abstracts in English
Furuno, Akiko; Omori, Ryuta*; Tateoka, Hisanori*; Minakawa, Yuya*; Kurihara, Toshiyuki; Yamamoto, Yoichi; Tomita, Yutaka
Pure and Applied Geophysics, 182(12), p.5175 - 5188, 2025/12
Times Cited Count：1 Percentile：14.96(Geochemistry & Geophysics)The Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) Okinawa radionuclide monitoring station (JPP37) is located on a hill facing the East China Sea at the center of the main island of Okinawa. It occasionally detects Cs-137, although no nuclear facilities are located on the island. This study focused on the detection of Cs-137 at JPP37 and examined the ratio of simultaneous detections at nearby stations of the International Monitoring System (IMS) of the CTBTO and the relationship with Asian dust from inland East Asia. The detection of Cs-137 in JPP37 from 2020 to 2023, which motivated this study, was high in spring. Among the nine IMS radionuclide stations in East Asia, the detections in Beijing, Lanzhou, and Ulaanbaatar, Mongolia, were also high in spring. This suggested a high association with the detection of Asian dust in East Asia. Thus, we confirmed the detection of Cs-137 at nine nearby IMS stations when Asian dust was observed at any of the sites in Japan. In addition, we observed that the detection rates were high in Takasaki, Beijing, Lanzhou, and Ulaanbaatar. It can be inferred that the Cs-137 observed mainly in spring at the IMS particulate radionuclide stations in the East Asian region around Japan were likely to pick up the effects of global fallout conveyed by Asian dust. Thereafter, we conducted a preliminary source estimation analysis for Asian dust arrival near Japan. Atmospheric dispersion simulations explained the detection of Cs-137 at nearby IMS particulate radionuclide stations, assuming that Cs-137 was emitted from the desert, the source of the Asian dust.
Takahashi, Tone; Koizumi, Mitsuo; Yoshimi, Yuki*; Mochimaru, Takanori*
JAEA-Technology 2025-007, 26 Pages, 2025/11
JAEA-Technology-2025-007.pdf:1.6MB
To prevent the smuggling of nuclear and radioactive materials into event venues for the purpose of terrorism, it is common practice to individually inspect people and vehicles entering and exiting using radiation detectors. However, since there remains a risk of such inspections being bypassed, it is necessary to complement them with a wide-area radiation survey to ensure that no nuclear or radioactive materials have been brought in. Radiation mapping is an effective method for efficiently surveying large areas. In this method, a gamma-ray detector equipped with GPS is used to record location data and radiation dose rates while moving. By utilizing network connectivity, measurement data from multiple detectors can be aggregated at a central command post, allowing real-time monitoring of survey progress. This system helps to prevent both redundant and missing measurements and enables the prompt detection of suspicious radiation sources. Furthermore, by incorporating spectrometers into the gamma -ray detectors, it becomes possible to identify radioactive isotopes, thereby enabling appropriate responses. To enable such wide-area radiation surveys, we developed real-time mapping software. The developed software receives measurement data transmitted from GPS-equipped gamma-ray spectrometers, processes it sequentially in real time, and plots it onto pre -downloaded map data. Additionally, by integrating the spectral data collected from regions showing abnormal radiation levels can be displayed immediately. To enhance information security, the software is designed to function within local networks without requiring internet connectivity. In this report, we introduce an overview of the developed software and provide a simplified version of the source code as an appendix. The provided code is developed using open and free operating systems, libraries, and environments, making it freely available and usable by anyone.
Takahashi, Tone; Mochimaru, Takanori*; Koizumi, Mitsuo; Yoshimi, Yuki*; Yamanishi, Hirokuni*; Wakabayashi, Genichiro*; Ito, Fumiaki*
JAEA-Review 2025-039, 34 Pages, 2025/11
JAEA-Review-2025-039.pdf:2.18MB
To prevent acts of terrorism involving nuclear or radioactive materials at major public events, it is required to have surveillance technologies that either prevent these materials from being brought in or detect quickly if somebody brings them in secretly. Setting radiation gate monitors to survey pedestrians and vehicles is one of the effective methods. However, considering the possibility of individuals bypassing these monitors, complementary technologies are needed to continuously survey areas inside the gates. To survey extensive areas, radiation mapping is effective. By using multiple detectors and aggregating the data, the survey becomes much more efficient. We have developed mobile detectors capable of simultaneously measuring location data and radiation levels outdoors, with the ability to aggregate measurement results via a network and immediately visualize them on a map. For indoor environments, we have developed a technology that integrates radiation measurement results with environmental mapping created using SLAM (Simultaneous Localization and Mapping) to produce 3D maps of the surveyed areas. Additionally, we have been working on the development of a source search technology using a fast neutron detector to quickly detect neutron sources, including nuclear materials. In this report, we describe a concept of the wide area survey system and report technology development results so far.
Kimura, Yoshiki; Yamaguchi, Tomoki
Radioisotopes, 74(3), p.251 - 264, 2025/11
Radioisotope identification (RIID) by gamma-ray spectral analysis has been widely used, and accurate identification of radioisotopes is an important issue in various fields. Handheld instruments are commonly used for on-site RIID but often suffer from limited performance. This paper proposes a spectral deconvolution using unsupervised neural network models for RIID with handheld instruments in field use. This approach allows optimization of the neural network for deconvolution based on a measured spectrum combined with an energy-broadening matrix, and it does not require extensive training datasets or the precise modeling of the detector and measurement conditions. The performance of the proposed approach was examined in simulated and measured spectra, assuming the measurements of several radioisotopes with CsI(Tl) spectrometers. It was demonstrated that the unsupervised neural network models can improve the peak resolution more significantly compared to conventional deconvolution algorithms and contribute to RIID performance in the low energy resolution spectra.
Shimizu, Ryo; Tazaki, Makiko; Kimura, Takashi; Hori, Masato
JAEA-Review 2025-030, 42 Pages, 2025/10
JAEA-Review-2025-030.pdf:1.35MB
To find measures to lead the expected denuclearization in the future successfully, effectively, and efficiently, we conducted the "Research on Factor Analysis and Technical Process for Achieving Denuclearization" from FY 2018 to FY2023. In the latter part of this research, as a study of the technical process to achieve denuclearization, the process of verification and dismantlement/disposal of nuclear materials and nuclear development-related facilities, etc., which are necessary to implement denuclearization in the target states, is studied based on technical knowledge and summarized with explanations especially from a technical perspective. However, nuclear weapons and their fabrication facilities were not included in the study because we do not have sufficient knowledge about them. These results will serve as a basis for future consideration of the denuclearization process and will also assist in considering how to guide the denuclearization of countries that have not yet achieved denuclearization, thereby contributing to the implementation of future denuclearization work.
Integrated Support Center for Nuclear Nonproliferation, Security and Human Resource Development
JAEA-Review 2025-029, 341 Pages, 2025/09
JAEA-Review-2025-029.pdf:6.27MB
The Integrated Support Center for Nuclear Nonproliferation, Security and Human Resources Development (ISCN) aims to realize a world without nuclear weapons and nuclear terrorism and to promote the sound development of nuclear science and technology. To achieve this goal and to promote public understanding of the importance of nuclear nonproliferation and nuclear security, the ISCN Newsletter is published monthly. This report is a re-edited version of articles in the category of "Trends in Nuclear Nonproliferation and Nuclear Security (Commentary and Analysis)" from the ISCN Newsletter published in fiscal year 2024 (April 2024 issue (No.0328) to March 2025 (No.0339)) by topic and chronological order to make it easier to understand the history of the 2024 fiscal year. Each article is basically published as it was when it was written and published, except for the unification of language and the notation of URLs as of April 2025 due to rechecking of references and sources in footnotes. In addition, a list of the above articles in the order of the publication of the Newsletter is posted as Appendix.
Kimura, Yoshiki; Yamaguchi, Tomoki
Progress in Nuclear Science and Technology (Internet), 7, p.60 - 66, 2025/03
Tanigawa, Masafumi; Seya, Kazuhito*; Asakawa, Naoya*; Hayashi, Hiroyuki*; Horigome, Kazushi; Mukai, Yasunobu; Kitao, Takahiko; Nakamura, Hironobu; Henzlova, D.*; Swinhoe, M. T.*; et al.
JAEA-Technology 2024-014, 63 Pages, 2025/02
JAEA-Technology-2024-014.pdf:3.02MB
The liquid waste treatment process generated sludge items at the plutonium conversion development facility. They are highly heterogeneous and contain large amounts of impurities (Na, Fe, Ni etc.). Therefore, the sludge items have very large sampling uncertainty and so the total measurement uncertainty is very large (approximately 24%). The plutonium scrap multiplicity counter (PSMC) measurement technique for sludge items was developed by joint research between the Japan Atomic Energy Agency (JAEA) and Los Alamos National Laboratory (LANL). The technical validity for sludge items using the PSMC was evaluated using various types of sample measurements and Monte Carlo N-Particle transport code calculations. The PSMC measurement parameters were found to be valid for use with sludge items and the validity of multiplicity analysis was confirmed and demonstrated through comparisons with standard MOX powder and a standard sludge. As a result, the PSMC measurement values were shown to be consistent and reasonable and the large amount of impurity (Fe, Ni etc.) did not impact the results. Therefore, the measurement uncertainty of the improved nuclear material accountancy (NMA) procedure by combined PSMC and high-resolution gamma spectrometry was shown to be 6.5%. In addition, an acceptance test was conducted using PSMC/HRGS and IAEA benchmark equipment. Measured Pu mass by both equipment agrees within the measurement uncertainty of each method, and so the validity for Pu mass measurement by PSMC/HRGS was confirmed. The above results confirm the applicability of PSMC/HRGS as an additional NMA method for sludge and a newly designed NDA procedure based on this study is applied to sludge for NMA in PCDF.
Lee, J.; Rossi, F.; Kodama, Yu; Hironaka, Kota; Koizumi, Mitsuo; Sano, Tadafumi*; Matsuo, Yasunori*; Hori, Junichi*
Annals of Nuclear Energy, 211, p.111017_1 - 111017_7, 2025/02
Times Cited Count：1 Percentile：23.55(Nuclear Science & Technology)