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Kai, Takeshi; Toigawa, Tomohiro; Matsuya, Yusuke*; Hirata, Yuho; Tsuchida, Hidetsugu*; Yokoya, Akinari*
Hoshasen Seibutsu Kenkyu, 61(2), p.112 - 126, 2026/06
This review introduces a chemical calculation code which can quantitatively evaluate the indirect effects of DNA damage. 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. 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 tens 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 by imparting energy to water in the extreme vicinity of DNA. Our results are one of the most important findings for understanding low-dose radiation risk.
Fujishima, Yohei*; Anderson, D.*; Abe, Yu*; Alkebsi, L.*; Oka, Toshitaka; Tani, Atsushi*; Kranrod, C.*; Toyoda, Shin*; Hamasaki, Kanya*; Hirota, Seiko*; et al.
Nihon Hoshasen Jiko, Saigai Igakkai Zasshi, 7(1), p.21 - 26, 2024/12
no abstracts in English
Hirata, Yuho; Kai, Takeshi; Ogawa, Tatsuhiko; Matsuya, Yusuke; Sato, Tatsuhiko
Hoshasen Kagaku (Internet), (118), p.21 - 28, 2024/10
Accurate dose evaluation by radiation detectors is crucial for the safe use of radiation. However, with certain types of radiation, the output from detectors can be nonlinear relative to the dose, thereby hindering correct dose assessments. To address these issues, it is vital to theoretically analyze the mechanisms affecting detector outputs. The radiation transport code PHITS includes a track structure analysis mode that precisely tracks radiation behavior. This review paper introduces the newly developed Electron Trajectory Structure Analysis Mode for Arbitrary Materials (ETSART), which facilitates the tracking of electron beams in various detector materials. Additionally, we present an example of phosphor quenching under ion beam irradiation, as analyzed using the PHITS track structure mode.
Hirose, Eri; Yokoya, Akinari*; Noguchi, Miho*; Huart, L.*; Suzuki, Keiji*
Hoshasen Seibutsu Kenkyu, 59(2), p.134 - 156, 2024/06
no abstracts in English
Mikami, Satoshi; Tokiyoshi, Masanori*; Sato, Rina*; Tanaka, Daisuke*; Yoshimura, Kazuya
Nihon Hoshasen Anzen Kanri Gakkai-Shi, 23(1), p.10 - 17, 2024/06
Taisei Corporation and Infocube LAFLA Co., Ltd. have developed the smartphone-wirelessly-connected dosemeters, aiming to apply it to real-time exposure management of multiple decontamination workers. In order to grasp the basic characteristics of the developed dosemeters, they were calibrated and tested their characteristics such as energy dependency, angle of incidence dependency, etc. at photon calibration fields in Japan Atomic Energy Agency. The results showed generally good characteristics in each test. We evaluated that the dosemeters can be effectively used for decontamination work.
Kumagai, Yuta
Hoshasen (Internet), 49(1), p.15 - 17, 2024/03
Water radiolysis induces oxidative dissolution of uranium oxides. Understanding of this process is a chemical basis for safety assessment of the deep geological repository of spent fuel and would serve as knowledge for retrieval and storage of fuel debris after a severe accident of nuclear power reactors. In order to evaluate the release rate of radioactive elements from the UO
matrix of spent nuclear fuel, several chemical kinetic models have been developed. However, the conventional reaction models were found out to be simplistic based on new insights obtained recent experimental studies. Therefore, the reaction mechanism of surface oxidation and dissolution of uranium is now a subject of revisit. Here, a few recent studies regarding the reaction mechanism are introduced.
Tagawa, Akihiro
Hoshasen (Internet), 49(1), p.2 - 4, 2024/03
The Great East Japan Earthquake occurred on March 11, 2011, and the accident at TEPCO's Fukushima Daiichi Nuclear Power Station caused widespread contamination in Fukushima Prefecture and elsewhere. JAEA started its activities on the day of March 11 when it was dispatched by a Self-Defense Forces helicopter from Hyakuri Air Base in Ibaraki Prefecture to the Okuma Town Off-Site Center. The activities included physical survey, health consultation telephone counter, temporary return home response for residents, whole body measurement of TEPCO employees and Fukushima Prefecture residents, environmental radiation monitoring, and others. The lecture reviewed the various events that took place during the first year after the disaster and introduced the dilemma under which JAEA has been working through simulated experiences.
Fujita, Natsuko; Matsubara, Akihiro*; Jinno, Satoshi; Kimura, Kenji
Hoshasen (Internet), 48(4), p.137 - 138, 2024/02
We have been developing a downsized AMS with a size of about 2 m 
2 m. This AMS is developed to demonstrate a new method of separating same-mass molecules, which are interfering nuclides during AMS measurement of carbon-14, using ion channeling.
Sr in environmental samples utilizing laser photo-detachmentHonda, Maki; Martschini, M.*; Marchhart, O.*; Steier, P.*; Golser, R.*; Sakaguchi, Aya*
Hoshasen (Internet), 48(4), p.130 - 136, 2024/02
Strontium-90 (Sr, 28.9 years) is a key fission product nuclide in internal dose assessment because it accumulates in bones and teeth in the body, causing health problems. Therefore, it is essential to know the distribution of Sr in the environment and its temporal variation (Sr enrichment in biota), which requires efficient analysis of many environmental samples. An analysis of environmental samples with known Sr concentrations conducted with the 3 MV AMS facility (VERA: Vienna Environmental Research Accelerator) at the University of Vienna, Austria, towards the practical application of Sr AMS, the results of which are detailed in this paper. In this study, the validity of the AMS method was demonstrated by analyzing environmental samples with known Sr concentrations (IAEA-447, IAEA-A-12, and IAEA-TEL-2015-03 sample 5: 1 dry-g each). The chemical separation developed in this study takes approximately two days and is a more straightforward procedure than conventional 
-ray detection methods. The Sr measurements were conducted on the AMS system combined with the Ion Laser InterAction Mass Spectrometry (ILIAMS) system. The AMS method achieved a limit of detection 
0.1 mBq ( 1.310
atoms) for Sr, which is 1/30th of typical -ray detection. As a result of the lower detection limit, the AMS method allows Sr quantification with smaller sample volumes. For example, a Japanese freshwater sample with a Sr concentration of 4 mBq/L requires a sample volume of 5 liter
Maeda, Shigetaka
Hoshasen Kagaku Furonteia, (5), P. 17, 2024/02
Regarding Actinium-225, which is one of the medical radioisotopes and has been attracting attention today, we will report on the domestic movement toward domestic production, the research and development plan and progress for production of Actinium-225 using the experimental fast reactor Joyo.
Kimura, Yoshiki; Takahashi, Tone; Hironaka, Kota; Mochimaru, Takanori*; Koizumi, Mitsuo
Hoshasen (Internet), 48(2), p.61 - 65, 2023/11
no abstracts in English
Arai, Masaji; Maeda, Shigetaka
Rinsho Hoshasen, 68(10), p.963 - 970, 2023/10
Ac-225 is attracting attention as an alpha-emitting medical radioisotope. Since its demand is expected to increase, domestic production of Ac-225 is required from the viewpoint of Japan's medical research and economic security. To establish the technical bases for the Ac-225 production, JAEA has evaluated the radioactivity that can be produced in the experimental fast reactor Joyo and designed the concept that upgrades the existing facilities for transporting the irradiated target from Joyo to a neighboring PIE facility rapidly. Efficient Actinium-225 Separation from Ra-226 irradiated in a fast reactor was studied. This study has revealed that Joyo can sufficiently produce Ac-225 as a raw material for pharmaceuticals.
Kawahara, Rika*; Ochi, Kotaro; Yamaguchi, Katsuhiko*; Torii, Tatsuo*
Hoshasen (Internet), 48(2), p.43 - 48, 2023/04
The accident at the Fukushima Daiichi NPP resulted in a large amount of radioactive material being dispersed into the surrounding environment. It is important to understand the radiation distribution in the area, which is still located in the difficult-to-return zone. In this study, a Compton camera and an optical camera were combined to produce a three-dimensional distribution map of source locations and their intensities. Two locations in the difficult-to-return zone (Okuma town) were surveyed: a park parking lot and the area around a private house. The distribution of air dose rates was determined by measurements with a survey meter with a wand-type GPS (Gamma Plotter H manufactured by Nippon Radiation Engineering Co. Measurements were taken with a Compton camera (H420, H3D, USA) at several different positions and angles towards the hotspots. The software (Application Programming Interface Example) allowed real-time confirmation of the radiation incident information (incident time, energy, x, y, z) obtained by the Compton camera. By photographing hotspots in high-dose areas from different positions and angles, the location of the radiation sources and their spatial extent could be confirmed.
Kumagai, Yuta
Hoshasen Kagaku (Internet), (115), p.43 - 49, 2023/04
Oxidation and dissolution of uranium oxide materials has been a subject of numerous studies as a basis of the geological disposal technology for spent nuclear fuel. The understandings obtained by these studies provide useful suggestions for research and development regarding the retrieval and storage of nuclear fuel debris generated by a nuclear severe accident. Here, these research backgrounds of oxidative dissolution of uranium oxides are briefly reviewed and some studies relating to radiation-induced reactions will be introduced.
Oka, Toshitaka
Shitterutsumori No Hoshasen Dokuhon , p.215 - 216, 2023/04
In relation to the estimation of external doses to wild Japanese macaques using ESR dosimetry, the history, principles, and sample preparation methods of ESR dosimetry are described.
Igarashi, Yu; Yamaguchi, Ichiro*; Oda, Keiji*; Fukushi, Masahiro*; Sakama, Minoru*; Iimoto, Takeshi*
Nihon Hoshasen Anzen Kanri Gakkai-Shi, 21(2), p.74 - 76, 2022/11
no abstracts in English
Terasaka, Yuta; Watanabe, Kenichi*; Uritani, Akira*
Hoshasen (Internet), 47(3), p.89 - 96, 2022/10
Hata, Kuniki; Sato, Tomonori
Hoshasen Kagaku (Internet), (114), p.33 - 38, 2022/10
no abstracts in English
O-induced oxidative degradation of simulated fuel debrisKumagai, Yuta; Kusaka, Ryoji; Nakada, Masami; Watanabe, Masayuki; Akiyama, Daisuke*; Kirishima, Akira*; Sato, Nobuaki*; Sasaki, Takayuki*
Hoshasen Kagaku (Internet), (113), p.61 - 64, 2022/04
The severe accident at TEPCO's Fukushima Daiichi Nuclear Power Station resulted in generation of fuel debris. The fuel debris is in contact with water and the radiolysis of water can accelerate degradation of the debris. The analysis of particles sampled from inside or near the damaged reactors indicates the complicated compositions of the fuel debris. It is challenging to estimate the effect of water radiolysis on such a complicated material. Therefore, in this study, we investigated the potential degradation process by leaching experiments of simulated fuel debris in aqueous HO solution. The results show that the reaction of HO induced uranium dissolution from most of the samples and then formation of uranyl peroxides. In contrast, a sample that had U-Zr oxide solid solution as the major phase exhibited remarkable resistance to HO. These findings revealed that the degradation of the simulated debris reflects the reactivity and stability of the uranium phase in the matrices.
