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Wada, Yuki*; Morimoto, Takeshi*; Wu, T.*; Wang, D.*; Kikuchi, Hiroshi*; Nakamura, Yoshitaka*; Yoshikawa, Eiichi*; Ushio, Tomoo*; Tsuchiya, Harufumi
Science Advances (Internet), 11(21), p.eads6906_1 - eads6906_10, 2025/05
Times Cited Count：0Endo, Akira
ESI-News, 43(2), p.37 - 41, 2025/04
The International Commission on Radiation Units and Measurements (ICRU) published ICRU Report 95 in 2020, revising the operational quantities for external exposure. This article provides an overview of the developments in the discussions within the ICRU, the International Commission on Radiological Protection (ICRP), and experts from Japan, and explores the background and process that led the ICRU to revise the operational quantities, as well as future responses and challenges. The article aims to enhance the understanding of the experts of the new operational quantities and to contribute to their smooth implementation in the future.
Kai, Takeshi; Toigawa, Tomohiro; Matsuya, Yusuke*; Hirata, Yuho; Tsuchida, Hidetsugu*; Yokoya, Akinari*
Journal of Chemical Physics, 162(15), p.154102_1 - 154102_11, 2025/04
Times Cited Count：0Scientific knowledge of low-energy electrons resulting from water radiolysis is required to estimate radiation DNA damage. However, since the analysis of water radiolysis is very complex, this study focuses on the experimental values of low-energy electrons related to simple water photolysis and those generated by photoirradiation of electrodes in water. Both experimental analyses involve the presence or absence of a Coulomb field in the parent ion. In this study, we analyzed these experimental values using a calculation code that combines Monte Carlo and molecular dynamics methods. As a result, it was shown that the code reproduced the experimental values even under different experimental conditions, and the code was validated. The calculation code will be a powerful tool for analyzing the interaction between low-energy electrons and DNA, and is expected to be applied to elucidate the formation mechanism of radiation DNA damage.
Joung, S.*; Ji, Y.-Y.*; Choi, Y.*; Lee, E.*; Ji, W.*; Sasaki, Miyuki; Ochi, Kotaro; Sanada, Yukihisa
Journal of Instrumentation (Internet), 20(4), p.P04027_1 - P04027_10, 2025/04
Times Cited Count：0Sweet, M.*; Mishima, Kenji*; Harada, Masahide; Kurita, Keisuke; Iikura, Hiroshi; Tasaki, Seiji*; Kikuchi, Norio*
Quantum Beam Science (Internet), 9(2), p.11_1 - 11_17, 2025/04
Neutron beam, being electrically neutral and highly penetrating, offers unique advantages for irradiation of biological species such as plants, seeds, and microorganisms. We comprehensively investigated the potential of neutron irradiation for inducing genetic mutations using simulations of J-PARC BL10, JRR-3 TNRF, and KUANS for spallation, reactor, and compact neutron sources.
Co gamma irradiation test results with calculated resultsTakeda, Ryoma; Shibata, Hiroshi; Takeuchi, Tomoaki; Nakano, Hiroko; Seki, Misaki; Ide, Hiroshi
JAEA-Testing 2024-007, 33 Pages, 2025/03
JAEA-Testing-2024-007.pdf:1.63MB
Japan Materials Testing Reactor (JMTR) in Oarai Research and Development Institute of the Japan Atomic Energy Agency (JAEA) has been developing various reactor materials, irradiation techniques and instruments for more than 30 years. Among them, the development of self-powered neutron detectors (SPNDs) and gamma detectors (SPGDs) has been carried out, and several research results have been reported. In this report, we compare and verify these test results with the theoretical output results obtained by the calculation code created in the JAEA report (JAEA-Data/Code 2021-018). The comparison was made with the irradiation test results of SPGD, a cobalt-60 gamma irradiation facility. As a result, it was found that the calculation results reproduced the test results well when the emitter diameter was relatively small compared to the range of Compton scattered electrons by the gamma rays. On the other hand, when the emitter diameter is relatively large, the output current in the test results is only about half of the calculated output current. The self-shielding effect of the emitter may be one of the reasons for the difference in the emitter diameter, and a new formulation, such as incorporating the effect of self-shielding caused by a larger emitter diameter or a non-isotropic 
-ray field as a change in the mean electron range or mean minimum energy in the calculation code, is necessary. The new formulation is necessary.
elik, Y.*; Stankovskiy, A.*; Iwamoto, Hiroki; Iwamoto, Yosuke; Van den Eynde, G.*
Annals of Nuclear Energy, 212, p.111048_1 - 111048_12, 2025/03
Times Cited Count：1 Percentile：57.00(Nuclear Science & Technology)Kai, Takeshi; Toigawa, Tomohiro; Matsuya, Yusuke*; Hirata, Yuho; Tsuchida, Hidetsugu*; Ito, Yuma*; Yokoya, Akinari*
Communications Chemistry (Internet), 8, p.60_1 - 60_9, 2025/03
Times Cited Count：1 Percentile：0.00(Chemistry, Multidisciplinary)Radiation DNA damage is formed from direct and indirect effects. The direct effect is the interaction between DNA and a radiation, while the indirect effect is the chemical reaction between DNA and radiolytic chemical species. We believed that when the direct effect is induced, multiple lesions are formed within 10 base pairs (about 3.4 nm) of DNA. The damage reduces repair efficiency and induces biological effects. In this study, DNA damage induced by only indirect effects was quantitatively evaluated. Our results indicated that the multiple damage is formed when only 10s of eV energy is deposited to water in the vicinity of DNA, although its formation probability is less than 1%. In other words, the possibility of late biological effects cannot be excluded simply by imparting energy to water in the extreme vicinity of DNA without direct interaction between radiation and DNA. Our results are one of the most important findings for understanding low-dose radiation risk.
Sasaki, Miyuki; Abe, Yuki*; Sanada, Yukihisa; Torii, Tatsuo*
Nuclear Instruments and Methods in Physics Research A, 1072, p.170207_1 - 170207_12, 2025/03
Times Cited Count：0 Percentile：0.00(Instruments & Instrumentation)We have developed an omnidirectional radiation imager with fractal geometry named the FRIE system. This paper presents the development and evaluation of the FRIE system, designed to accurately estimate radioactivity distribution within decommissioning environments, such as the Fukushima Daiichi Nuclear Power Station. The FRIE system is a unit of tetrahedral radiation sensors; 16 sensors are arranged in a Sierpinski tetrahedron shape, and the space between the sensors is filled with tungsten-based alloy for radiation shielding. This study assessed the performance of the FRIE system in estimating radiation distribution through simulations and actual measurement tests. From the results of the simulations and experimental data, it was confirmed that by maintaining a measurement density of at least 2 points/m
, limiting the positional error to within 
10 cm, and the angular error to within 10 degrees, it is possible to estimate the source location with an angular resolution of approximately 30 degrees. Future improvements in the arrangement of the FRIE system's crystals and shielding should enhance the performance metrics. This research signifies a pioneering implementation of fractal-based radiation imaging technology, offering a new direction in radiation measurement.
Sato, Yuki
Radioisotopes, 74(1), p.141 - 148, 2025/03
no abstracts in English
Miyazaki, Yasunori; Sano, Yuichi; Ishigami, Ryoya*
EPJ Web of Conferences, 317, p.01006_1 - 01006_7, 2025/01
Times Cited Count：0 Percentile：0.00(Chemistry, Inorganic & Nuclear)The gamma-ray and He
ion beam (which is simulated for alpha-ray from 
Am, for example) were irradiated on the TEHDGA adsorbent to evaluate the hydrogen gas production, leaching amount of organics in the immersed 3 M HNO
solution, thermal characteristics and speciation of the degradation products. These were combined to assess the safety of the 1st run of the MA separation process from the raffinate at a dose rate of 1 kGy/h.
Sato, Yuki
FBNews, (577), p.2 - 6, 2025/01
no abstracts in English
Endo, Akira
Annals of the ICRP, 52(4), p.5 - 7, 2024/12
In its Publication 155, International Commission on Radiological Protection (ICRP) has developed data on the Specific Absorbed Fraction (SAF) for reference males and females at ages of newborn, 1 year, 5 years, 10 years, and 15 years. The SAF represents the fraction of energy emitted within a source region which is absorbed in a target region per mass of the target region and is essential for calculating absorbed doses in organs or tissues for internal exposure. By combining the data of Publication 155 with the SAF data for reference adult males and females already published as Publication 133, an SAF dataset for the calculation of age-dependent dose coefficients for members of the public for environmental intakes of radionuclides has been completed. This, together with revised biokinetic models and nuclear decay data, means that the key building blocks for calculating new dose coefficients are in place. The outcome will soon be available in a series of ICRP Publications of Dose Coefficients for Intakes of Radionuclides by Members of the Public.
Sato, Nobuaki*; Kameo, Yutaka; Sato, Soichi; Kumagai, Yuta; Sato, Tomonori; Yamamoto, Masahiro*; Watanabe, Yutaka*; Nagai, Takayuki; Niibori, Yuichi*; Watanabe, Masayuki; et al.
Introduction to Dismantling and Decommissioning Chemistry, 251 Pages, 2024/09
This book focuses on the dismantling and decommissioning of nuclear facilities and reactors that have suffered severe accidents. In Part 1, we introduce basic aspects ranging from fuel chemistry, analytical chemistry, radiation chemistry, corrosion, and decontamination chemistry to waste treatment and disposal. Then, Part 2 covers the chemistry involved in the decommissioning of various nuclear facilities, and discusses what chemical approaches are necessary and possible for the decommissioning of TEPCO's Fukushima Daiichi Nuclear Power Plants, how decommissioning should be carried out, and what kind of research and development and also human resource development are required for this.
Tsuchida, Hidetsugu*; Tezuka, Tomoya*; Kai, Takeshi; Matsuya, Yusuke*; Majima, Takuya*; Saito, Manabu*
Journal of Chemical Physics, 161(10), p.104503_1 - 104503_8, 2024/09
Times Cited Count：0 Percentile：0.00(Chemistry, Physical)Although fast ion beams can damage DNA by chemical products such as secondary electrons produced by their interaction with water in living cells, the process of formation of these chemical products in the Bragg peak region used in particle therapy is not fully understood. To investigate this process, we performed experiments to evaluate the yields of radiolytic products produced when a liquid water jet in vacuum is irradiated with a MeV-energy carbon beam. In addition, ionization processes in water due to incident ions and secondary electrons were simulated using a radiation transport Monte Carlo code. The results indicated that the primary source of ionization in water is secondary electrons. Finally, we show that these elementary processes contribute to the development of radiation biophysics and biochemistry to study the formation mechanism of DNA damage.
Machida, Masahiko; Yamada, Susumu; Kim, M.; Tanaka, Satoshi*; Tobita, Yasuhiro*; Iwata, Ayako*; Aoki, Yuto; Aoki, Kazuhisa; Yanagisawa, Kenichi*; Yamaguchi, Takashi; et al.
RIST News, (70), p.3 - 22, 2024/09
Inside the Fukushima Daiichi Nuclear Power Plant (1F), there are many locations with high radiation levels due to contamination by radioactive materials that leaked from the reactor. These pose a significant obstacle to the smooth progress of decommissioning work. To help solve this issue, the Japan Atomic Energy Agency (JAEA), under a subsidy from the Ministry of Economy, Trade, and Industry's decommissioning and contaminated water management project, is conducting research and development on digital technologies to improve the radiation environment inside the decommissioning site. This project, titled "Development of Technology to Improve the Environment Inside Reactor Buildings (Enhancing Digital Technology for Environment and Source Distribution to Reduce Radiation Exposure)," began in April of FY 2023. In this project, the aim is to develop three interconnected systems: FrontEnd, Pro, and BackEnd. The FrontEnd system, based on the previously developed 3D-ADRES-Indoor (prototype) from FY 2021-2022, will be upgraded to a high-speed digital twin technology usable on-site. The Pro system will carry out detailed analysis in rooms such as the new office building at 1F, while the BackEnd system will serve as a database to centrally manage the collected and analyzed data. This report focuses on the FrontEnd system, which will be used on-site. After point cloud measurement, the system will quickly create a 3D mesh model, estimate the radiation source from dose rate measurements, and refine the position and intensity of the estimated source using recalculation techniques (re-observation instructions and re-estimation). The results of verification tests conducted on Unit 5 are also presented. Furthermore, the report briefly discusses the future research and development plans for this project.
Nagai, Haruyasu; Nakayama, Hiromasa; Satoh, Daiki; Tanimori, Toru*
Dai-52-Kai Kashika Joho Shimpojiumu Koen Rombunshu (Internet), 4 Pages, 2024/07
A novel monitoring method for the quantitative visualization of 3D distribution of a radioactive plume accidentally released from a nuclear facility is proposed, and the feasibility of its analysis method is demonstrated by preliminary test using hypothetical data. The proposed method is the combination of gamma-ray imaging spectroscopy with the electron tracking Compton camera (ETCC) and real-time high-resolution atmospheric dispersion simulation based on 3D wind observation with Doppler lidar. ETCC can acquire the angle distribution images of direct gamma-ray from a specific radionuclide in a target radioactive plume. The 3D distribution of radioactive plume is inversely reconstructed from direct gamma-ray images by several ETCCs located around the target by harmonizing with the air concentration distribution pattern of the plume predicted by real-time atmospheric dispersion simulation. Analysis methods were developed and tested by using hypothetical data generated by numerical simulations of atmospheric dispersion and radiation transport.
Tanigawa, Masafumi; Nakamura, Daishi; Asakawa, Naoya*; Seya, Kazuhito*; Omori, Fumio*; Koiso, Katsuya*; Horigome, Kazushi; Shimizu, Yasuyuki
JAEA-Technology 2024-001, 37 Pages, 2024/05
JAEA-Technology-2024-001.pdf:2.32MB
At plutonium conversion development facility, the neutralization sedimentation and the coagulation sedimentation (sludge) items are stored in a polyethylene container packed in the plastic bag. The neutralization sedimentation items and the coagulation sedimentation items are stored in the globe box and storage room in the facility, respectively. Some sludge items generate gases, that swelled the plastic bag. We should ensure whether the bag swelling by visual confirmation. When the swelling is confirmed, those containers are transferred to the glove box to exchange the plastic bag for new one. By keeping the above procedure, those items were stored safely in the facility since its founding. The stabilization work for enhance the safe storage was planned to reduce the gas generation of the sludge items caused by the radiolysis of water. Those sludge items have the containing a sodium nitrate that has moisture-absorption characteristic. Therefore, the stabilization method aimed to remove the sodium nitrate from the items. The work was conducted from August 2018 to August 2022. The sodium concentration in items were reduced to 3 wt% or lower. Each stabilized sludge item packed in plastic bag were confirmed its swelling for over one year in the storage place. No gas generation from all item has been observed for more than the one year. And while both the neutralization and the coagulation sedimentation items were stored they were not the increasing of the moisture in the items. As a result, those items were evaluated that will not generate gases any more and confirmed to be stabilized after this treatment. Then, those neutralization sedimentation items were stored in powder cans and transferred to powder storage room as a retained waste. Based on the above results, risks of the gas generation from sludge items were decreased enough. Therefore, the safety of the stored sludge item was improved and confirmed.
Tsuchiya, Harufumi; Hibino, Kinya*; Kawata, Kazumasa*; Onishi, Munehiro*; Takita, Masato*; Munakata, Kazuoki*; Kato, Chihiro*; Shimoda, Susumu*; Shi, Q.*; Wang, S.*; et al.
Progress of Earth and Planetary Science (Internet), 11, p.26_1 - 26_14, 2024/05
Times Cited Count：0 Percentile：0.00(Geosciences, Multidisciplinary)Takasaki, Koji
Hokeikyo Nyusu, (73), p.2 - 5, 2024/04
The development of radiation measurement and digital technology for the decommissioning of the Fukushima Daiichi Nuclear Power Plant, which is being conducted by the Remote System and Sensing Technology Division of CLADS, will be presented.
