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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.
Honda, 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 (
1.3
10
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
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.
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.
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
Kumagai, 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 H
O
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 H
O
. These findings revealed that the degradation of the simulated debris reflects the reactivity and stability of the uranium phase in the matrices.
Matsuya, Yusuke; Kai, Takeshi; Ogawa, Tatsuhiko; Hirata, Yuho; Sato, Tatsuhiko
Hoshasen Kagaku (Internet), (112), p.15 - 20, 2021/11
Particle and Heavy Ion Transport code System (PHITS) is a general-purpose Monte Carlo code enabling radiation kinetics, which is often used in diverse research fields, such as atomic energy, engineering, medicine and science. After released in 2010, the PHITS code has been developed to expand its functions and to improve its convenience. In the few years, track-structure mode has been introduced in PHITS that can simulate each atomic interaction by electrons, positions, protons and carbon ions in liquid water. Thanks to the development of track-structure mode, the latest PHITS code enables microscopic dose calculations by decomposing it to the scale of DNA. Aiming at realizing the track-structure mode with high precision, the further developments of electron and ion track-structure mode for arbitrary materials are recently ongoing. This review shows the development history and future prospect of PHITS track-structure mode, which can expect to be further applied to the research fields of atomic physics, radiation chemistry, and quantum life science.
Miyazaki, Yasunori; Sano, Yuichi
Hoshasen Kagaku (Internet), (112), p.27 - 32, 2021/11
no abstracts in English
Kanzaki, Norie
Hoshasen Seibutsu Kenkyu, 56(3), p.295 - 307, 2021/09
The biological effects of low-dose radiation are confusing due to the various intertwined factors. The vital body responses are complex. In this review, we visualized the results of animal experiments using Self-organizing maps (SOM) and reported the results of the low-dose radiation biological effect assessment from a different viewpoint. For example, although the classification of these data which were the biological effects by low-dose radiation were impossible, SOM got the overall assessment and the intuitive understanding. We reported the results and the usefulness of data visualization of radiation biological effects using machine learning.
Fukunaga, Hisanori*; Matsuya, Yusuke
Hoshasen Seibutsu Kenkyu, 56(2), p.208 - 223, 2021/06
Boron Neutron Capture Therapy (BNCT) is one of the radiation therapies, enabling selectively eradicating tumors by short-range a-particles and Li ions generated through the nuclear reaction between thermal neutron and B within tumor cells. With the development of the accelerator-based neutron source in the recent decades, it is expected that BNCT will be available in many medical facilities worldwide in the future. BNCT irradiation needs a relatively long dose-delivery time after taking up boron drug into tumor cells by intravenous injection. During the period, it is suspected that the boron drug is heterogeneously taken up into cells and its concentration changes continuously, leading to the modification of curative effects from the pharmacological and biological viewpoints. However, the model development for precisely predicting curative effects after BNCT irradiation is still ongoing. Here, we introduce the forefront of model development for estimating the curative effects during BNCT irradiation with high accuracy. This review can create the synergetic effects through an interdisciplinary research approach that can connect the fields of physics, pharmacology, biology and medicine, and would pave the way for new era of BNCT.
Torii, Tatsuo*; Sanada, Yukihisa
Hoshasen, 46(3), p.93 - 101, 2021/05
Ten years have passed since the Fukushima Nuclear Power Plant accident, and various measurements of radiation conditions in the environment are revealing the relationship between changes in trends and their environmental factors. In radiation measurement technology, many new methods have been proposed for environmental measurement and decommissioning after the accident. This paper outlines these latest trends.
Oka, Toshitaka; Takahashi, Atsushi*
Hoshasen Kagaku (Internet), (110), p.13 - 19, 2020/10
The article depicts how to estimate the external exposure dose for wild animals using electron spin resonance (ESR) spectroscopy. The relationship between the CO radical intensity and the absorbed dose, that is, dose response curve of tooth enamel of Japanese macaque was observed, and the detection limit of our method was estimated. The estimated detection limit of 33.5 mGy is comparable to the previously reported detection limit for human molar teeth. The external exposure dose for seven wild Japanese macaques captured in Fukushima prefecture were examined using this dose response curve. The estimated external exposure dose were ranged between 45 mGy to 300 mGy.