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Terada, Atsuhiko; Thwe Thwe, A.; Hino, Ryutaro*; Harai, Yasutaka*; Sasaki, Gaku*; Shingeya, Hideshi*; Yamashita, Toshiyuki*; Yoneda, Jiro*; Okabayashi, Kazuki*; Sakamoto, Hiroyuki*; et al.
JAEA-Data/Code 2025-012, 151 Pages, 2025/12
JAEA-Data-Code-2025-012.pdf:9.69MB
Based on the lessons learned from the Fukushima Daiichi Nuclear Power Station accident, we have highly paid attention to the advancement of the fundamental technologies which are indispensable in timely response to hydrogen safety measures and assessments especially in both nuclear reactors and decommissioning. Focusing on this attention, we developed an analysis system that predicts the behavior of hydrogen from generation to diffusion, combustion and explosion. The system utilizes the commercial computational fluid dynamics software (FLUENT, AUTODYN), and incorporates new modules and pre/post-processors in order to withstand the general practical use. We also developed a system by utilizing open-source code (OpenFOAM) that can be used in hydrogen disaster prevention plans for nuclear facilities. So far, we have expanded the system to deal with the phenomena that should be considered from the practical point of view for PWR (Pressurized Water Reactor) in nuclear power plants. This report summarizes the overview of the integrated analysis system for hydrogen behavior, the handling method, and real scale analysis examples.
Hayashi, Teppei*; Yamashita, Takuma*; Mitsuyasu, Yusuke*; Ono, Kenta*; Iwami, Satone*; Kino, Yasushi*; Sekine, Tsutomu*; Oka, Toshitaka; Takahashi, Atsushi*; Shimizu, Yoshinaka*; et al.
International Journal of Radiation Biology, 8 Pages, 2025/00
Times Cited Count：0 Percentile：0.00(Biology)no abstracts in English
Yamashita, Takuma*; Hayashi, Teppei*; Mitsuyasu, Yusuke*; Ono, Kenta*; Iwami, Satone*; Kino, Yasushi*; Sekine, Tsutomu*; Oka, Toshitaka; Takahashi, Atsushi*; Shimizu, Yoshinaka*; et al.
International Journal of Radiation Biology, 8 Pages, 2025/00
Times Cited Count：1 Percentile：68.76(Biology)no abstracts in English
Yamashita, Takuma*; Iwami, Satone*; Mitsuyasu, Yusuke*; Ono, Kenta*; Oka, Toshitaka; Takahashi, Atsushi*; Kino, Yasushi*; Sekine, Tsutomu*; Shimizu, Yoshinaka*; Chiba, Mirei*; et al.
KEK Proceedings 2024-6, p.85 - 90, 2024/12
To clarify the radiation effects of the accident at the TEPCO's Fukushima Daiichi NPP on living organisms, it is important to accurately estimate the dose to each individual. We have developed a multi-component analysis program using random number optimization to extract only the components derived from carbonate radicals from the ESR spectra.
Iwami, Satone*; Yamashita, Takuma*; Mitsuyasu, Yusuke*; Ono, Kenta*; Oka, Toshitaka; Takahashi, Atsushi*; Kino, Yasushi*; Sekine, Tsutomu*; Shimizu, Yoshinaka*; Chiba, Mirei*; et al.
KEK Proceedings 2024-6, p.91 - 95, 2024/12
We aim to improve the detection limit of the ESR dosimetry method. In this study, the saturation behavior of each radical was investigated by varying the microwave power during ESR measurement. Based on the difference in spin relaxation time between carbonate radicals and native radicals, it is expected that the signal-to-noise ratio improves and the detection limit can be lowered when the microwave power is increased to 4.0 mW.
Mitsuyasu, Yusuke*; Oka, Toshitaka; Takahashi, Atsushi*; Kino, Yasushi*; Okutsu, Kenichi*; Sekine, Tsutomu*; Yamashita, Takuma*; Shimizu, Yoshinaka*; Chiba, Mirei*; Suzuki, Toshihiko*; et al.
Radiation Protection Dosimetry, 199(14), p.1620 - 1625, 2023/09
Times Cited Count：2 Percentile：31.60(Environmental Sciences)We have been conducting dose assessments for Japanese macaques captured in Fukushima to reveal radiobiological effects on the low-dose expose animals. To accurately determine the external exposure dose, it is desirable to examine the analysis of the CO
radical intensity. We examined ESR spectra of teeth of 10 macaques captured in Fukushima by two spectrum-decomposition algorithms.
Mitsuyasu, Yusuke*; Oka, Toshitaka; Takahashi, Atsushi*; Kino, Yasushi*; Okutsu, Kenichi*; Sekine, Tsutomu*; Yamashita, Takuma*; Shimizu, Yoshinaka*; Chiba, Mirei*; Suzuki, Toshihiko*; et al.
KEK Proceedings 2022-2, p.120 - 125, 2022/11
We investigate the effect of sample's anisotropy and measurement condition to obtain the higher reproducibility for the shape of the ESR spectrum and the intensity of CO radical.
Oka, Toshitaka; Takahashi, Atsushi*; Koarai, Kazuma; Kino, Yasushi*; Sekine, Tsutomu*; Shimizu, Yoshinaka*; Chiba, Mirei*; Suzuki, Toshihiko*; Osaka, Ken*; Sasaki, Keiichi*; et al.
Journal of Radiation Research (Internet), 63(4), p.609 - 614, 2022/07
Times Cited Count：5 Percentile：43.28(Biology)Electron spin resonance (ESR) dosimetry is one of the most powerful tools for radiation dose reconstruction. The detection limit of this technique using human teeth is reported to be 56 mGy or 67 mGy; however, the absorbed dose of Fukushima residents after the Fukushima Daiichi Nuclear Power Plant (FNPP) accident was estimated to be lower than this detection limit. Our aim is to assess the absorbed radiation dose of children in Fukushima Prefecture after the accident; therefore, it is important to estimate the detection limit for their teeth. The detection limit for enamel of deciduous teeth of Japanese children separated by the mechanical method is estimated to be 115.0 mGy. The density separation method can effectively separate enamel from third molars of Japanese people. As we have collected thousands of teeth from children in Fukushima, the present technique may be useful to examine their external absorbed dose after the FNPP accident.
Mitsuyasu, Yusuke*; Oka, Toshitaka; Takahashi, Atsushi*; Koarai, Kazuma; Kino, Yasushi*; Okutsu, Kenichi*; Sekine, Tsutomu*; Yamashita, Takuma*; Shimizu, Yoshinaka*; Chiba, Mirei*; et al.
KEK Proceedings 2021-2, p.91 - 96, 2021/12
We examined whether the ESR dose estimation method could be applied to wild Japanese macaque. In this work, we investigated the enamel preparation protocol and the analytical method of the ESR spectra.
Sr in cattle bone and tooth samples by inductively coupled plasma mass spectrometryKoarai, Kazuma; Matsueda, Makoto; Aoki, Jo; Yanagisawa, Kayo*; Terashima, Motoki; Fujiwara, Kenso; Kino, Yasushi*; Oka, Toshitaka; Takahashi, Atsushi*; Suzuki, Toshihiko*; et al.
Journal of Analytical Atomic Spectrometry, 36(8), p.1678 - 1682, 2021/08
Times Cited Count：8 Percentile：52.37(Chemistry, Analytical)Rapid analysis of Sr in bone and tooth samples of cattle were achieved by an inductively coupled plasma mass spectrometry (ICP-MS) coupled with mass shift and solid phase extraction techniques. Limit of detection (LOD) in the ICP-MS measurement of 0.1 g samples was lower than that of the radioactivity measurement. Analytical time of the ICP-MS method was reduced from 20 days to 11 hours, compared with the radiometric method. Therefore, the ICP-MS method can be rapid and useful procedure of Sr in small bone and tooth samples derived from terrestrial animals.
Takahashi, Atsushi*; Chiba, Mirei*; Tanahara, Akira*; Aida, Jun*; Shimizu, Yoshinaka*; Suzuki, Toshihiko*; Murakami, Shinobu*; Koarai, Kazuma; Ono, Takumi*; Oka, Toshitaka; et al.
Scientific Reports (Internet), 11(1), p.10355_1 - 10355_11, 2021/05
Times Cited Count：13 Percentile：46.50(Multidisciplinary Sciences)Oka, Toshitaka; Takahashi, Atsushi*; Koarai, Kazuma; Mitsuyasu, Yusuke*; Kino, Yasushi*; Sekine, Tsutomu*; Shimizu, Yoshinaka*; Chiba, Mirei*; Suzuki, Toshihiko*; Osaka, Ken*; et al.
Radiation Measurements, 134, p.106315_1 - 106315_4, 2020/06
Times Cited Count：10 Percentile：64.09(Nuclear Science & Technology)The relationship between the CO
radical intensity and the absorbed dose (dose response curve) of tooth enamel of Japanese macaque was observed by electron spin resonance and the detection limit of our system was estimated to be 33.5 mGy, which is comparable to the detection limit for human molar teeth. Using the dose response curve, external exposure dose for seven wild Japanese macaques captured in Fukushima prefecture were examined. The results suggest that the external exposure dose for the wild Japanese macaques were ranged between 45 mGy to 300 mGy.
Sakanaka, Shogo*; Ago, Tomonori*; Enomoto, Atsushi*; Fukuda, Shigeki*; Furukawa, Kazuro*; Furuya, Takaaki*; Haga, Kaiichi*; Harada, Kentaro*; Hiramatsu, Shigenori*; Honda, Toru*; et al.
Proceedings of 11th European Particle Accelerator Conference (EPAC '08) (CD-ROM), p.205 - 207, 2008/06
Future synchrotron light sources based on the energy-recovery linacs (ERLs) are expected to be capable of producing super-brilliant and/or ultra-short pulses of synchrotron radiation. Our Japanese collaboration team is making efforts for realizing an ERL-based hard X-ray source. We report recent progress in our R&D efforts.
Ichige, Hisashi; Honda, Masao; Sasaki, Shunichi; Takenaga, Hidenobu; Matsuzawa, Yukihiro; Haga, Saburo; Ishige, Yoichi
JAEA-Technology 2007-037, 16 Pages, 2007/07
JAEA-Technology-2007-037.pdf:2.91MB
In JT-60U, pellet injector has been developed for improvement of density controllability and long operation duration consistent with a long pulse discharge (
65 s) started from FY2003. The injection frequency and operation duration were limited by extrusion speed and volume of the piston type pellet extruder, respectively, in the previous system. The screw type pellet extruder made in Russian company was newly installed in the system, which can continuously extrude the pellet at high speed and has been used in other fusion devices. After parts of the pellet injector system moved from JT-60 torus hall for efficient work, the previous piston type pellet extruder was changed to the new screw type pellet extruder and the tests for continuous pellet extrusion were performed. In the extrusion test using deuterium gas as a working gas, continuous pellet extrusion up to 330s was achieved, which is sufficient performance for applying it to JT-60U experiments.
Chijimatsu, Masakazu*; Fukudome, Kazuto*; Urano, Kazuhiko*; Imai, Hisashi*; Sasaki, Hajime*; Amemiya, Kiyoshi*
JNC TJ8400 2004-027, 87 Pages, 2005/02
JNC-TJ8400-2004-027.pdf:2.13MB
This study investigates the methodology for the engineered barriers performance confirmation. First of all the investigation about the monitoring concept in foreign countries were performed and the monitoring aiming was fixed at the performance confirmation of the engineered barriers. The monitoring item and the element of engineered barriers were set as followings, namely temperature, hydraulic pressure, water contents, pH, Eh and the chemistry of solutions. The indirect measuring method of items both providing the engineered barriers performance and varying with exhibition of performance from the rock around the engineered barriers is proposed for the engineered barriers performance confirmation monitoring.
Chijimatsu, Masakazu*; Imai, Hisashi*; Sasaki, Hajime*; Moro, Yoshiji*
JNC TJ8400 2003-090, 116 Pages, 2004/02
JNC-TJ8400-2003-090.pdf:3.43MB
This study investigates the methodology for the engineered barriers performance confirmation. First of all the investigation about the monitoring concept in foreign countries were performed and the monitoring aiming was fixed at the performance confirmation of the engineered barriers. The monitoring item and the element of engineered barriers were set as followings, namely temperature, hydraulic pressure, water contents, pH, Eh and the chemistry of solutions. The indirect measuring method of items both providing the engineered barriers performance and varying with exhibition of performance from the rock around the engineered barriers is proposed for the engineered barriers performance confirmation monitoring. Finally the problems to be solved for the future monitoring program are clarified, and the plan of R&D for sensing methods in the performance assessment, and the in-situ experimental plan in the Horonobe deep underground research center are proposed.
Chijimatsu, Masakazu*; Imai, Hisashi*; Fukudome, Kazuto*; Kayukawa, Koji*; Sasaki, Hajime*; Moro, Yoshiji*
JNC TJ8400 2003-089, 354 Pages, 2004/02
JNC-TJ8400-2003-089.pdf:17.22MB
After emplacement of the engineered barrier system (EBS), it is expected that the near-field environment will be impacted by phenomena such as heat dissipation by conduction and other heat transfer mechanisms, infiltration of groundwater from the surrounding rock in to the engineered barrier system, stress imposed by the overburden pressure and generation of swelling pressure in the buffer due to water infiltration. In order to recognize and evaluate these coupled thermo-hydro-mechanical (THM) phenomena, it is necessary to make a confidence of the mathematical models and computer codes. Evaluating these coupled THM phenomena is important in order to clarify the initial transient behavior of the EBS within the near field. DECOVALEX project is an international co-operative project for the DEvelopment of COupled models and their VALidation against EXperiments in nuclear waste isolation and it is significance to participate this project and to apply the code for the validation. Therefore, we tried to apply the developed numerical code against the subjects of DECOVALEX. We carried out the simulation against the Task1 (simulation of FEBEX in-situ full-scale experiment), Task 3 BMT1 (Bench Mark Test against the near field coupling phenomena) and Task3 BMT2 (Bench Mark Test against the up-scaling of fractured rock mass). This report shows the simulation results against these tasks. Furthermore, technical investigations about the in-situ full-scale experiment (called Prototype Repository Project) in Aspo HRL facility by SKB of Sweden were performed. In order to evaluate the coupled phenomena in the engineered barrier, we use the new swelling model based on the theoretical approach. In this paper, we introduce the modeling approach and applicability about the new model.
Imai, Hisashi*; Fukudome, Kazuto*; Kayukawa, Koji*; Sasaki, Hajime*; Chijimatsu, Masakazu*; Moro, Yoshiji*
JNC TJ5400 2003-009, 223 Pages, 2004/02
JNC-TJ5400-2003-009.pdf:59.94MBJNC-TJ5400-2003-009(errata).pdf:0.08MB
In order to search for an appropriate methodology of the regional groundwater flowanalysis for sedimentary rock mass area, the following four studies were carried out: 1) Two simulation region setting and data set arrangement of the two region for numerical simulation of groundwater flow 2) Evaluation of regional groundwater flow characteristics in the Horonobe Project site using the results of the numerical simulation and obtained field data 3) Estimation of the shaft excavation effect on the groundwater flow such as the inflow rate of groundwater into the shafts, the chroline contents of groundwater flowing into the shafts and the hydraulic head evolution around the shafts 4) Proposal of desirable investigations for the next stage : the methodology of evaluating groundwater flow characteristics
Sasaki, Akira; Sudo, Keiko; Yokota, Hisashi*
JAERI-Data/Code 2002-003, 54 Pages, 2002/03
JAERI-Data-Code-2002-003.pdf:4.26MB
no abstracts in English
Kizu, Kaname; Hosogane, Nobuyuki; Hiratsuka, Hajime; Ichige, Hisashi; Sasajima, Tadayuki; Masaki, Kei; Miya, Naoyuki; Honda, Masao; Iwahashi, Takaaki*; Sasaki, Noboru*; et al.
Fusion Engineering and Design, 58-59, p.331 - 335, 2001/11
Times Cited Count：16 Percentile：72.06(Nuclear Science & Technology)no abstracts in English
