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Myagmarjav, O.; Tanaka, Nobuyuki; Noguchi, Hiroki; Kamiji, Yu; Ono, Masato; Nomura, Mikihiro*; Takegami, Hiroaki
Progress in Nuclear Science and Technology (Internet), 7, p.235 - 242, 2025/05
Yamamoto, Keisuke; Nakagawa, Takuya; Shimojo, Hiroto; Kijima, Jun; Miura, Daiya; Onose, Yoshihiko*; Namba, Koji*; Uchida, Hiroaki*; Sakamoto, Kazuhiko*; Ono, Chika*; et al.
JAEA-Technology 2024-019, 211 Pages, 2025/02
JAEA-Technology-2024-019.pdf:35.35MB
The uranium enrichment facilities at the Nuclear Fuel Cycle Engineering Laboratories of Japan Atomic Energy Agency (JAEA) were constructed sequentially to develop uranium enrichment technology with centrifugal separation method. The developed technologies were transferred to Japan Nuclear Fuel Limited until 2001. And the original purpose has been achieved. Wastewater Treatment Facility, one of the uranium enrichment facilities, was constructed in 1976 to treat radioactive liquid waste generated at the facilities, and it finished the role in 2008. In accordance with the Medium/Long-Term Management Plan of JAEA Facilities, interior equipment installed in this facility had been dismantled and removed since November 2021 to August 2023. This report summarizes the findings obtained through the work related to the contamination inspection methods cancellation the controlled area of Wastewater Treatment Facility from September 2023 to March 2024.
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.
-HO system using deep neural networkTanaka, Nobuyuki; Takegami, Hiroaki; Noguchi, Hiroki; Kamiji, Yu; Myagmarjav, O.; Ono, Masato; Sugimoto, Chihiro
Chemical Engineering Science, 299, p.120479_1 - 120479_11, 2024/11
Times Cited Count：0 Percentile：0.00(Engineering, Chemical)We developed a deep neural network method to predict the composition of the iodine-sulfur process of thermochemical water-splitting hydrogen production using measurable properties. Unlike conventional titration analysis, this approach allows a quick understanding of fluid composition, providing essential information for controlling operating conditions. This study focused on the HI-I-HO three-component system within the IS process. Using Gibbs phase rule, the DNN model was constructed using online measurable parameters, such as temperature, pressure, and density, as input conditions. The model was trained with experimental data, and the structural parameters were tuned. Composition prediction using actual trend data demonstrated good correlation with titration analysis measurements. Furthermore, the local interpretable model-agnostic explanations method was incorporated to gain insights into the significance of input parameters for compositions from the DNN model, providing valuable information on crucial parameters for effective composition control.
Shimokita, Keisuke*; Yamamoto, Katsuhiro*; Miyata, Noboru*; Shibata, Motoki*; Nakanishi, Yohei*; Arakawa, Masato*; Takenaka, Mikihito*; Kida, Takumitsu*; Tokumitsu, Katsuhisa*; Tanaka, Ryo*; et al.
Langmuir, 40(30), p.15758 - 15766, 2024/07
Times Cited Count：0 Percentile：0.00(Chemistry, Multidisciplinary)
C ions based on first-principles calculationsSekikawa, Takuya; Matsuya, Yusuke; Hwang, B.*; Ishizaka, Masato*; Kawai, Hiroyuki*; Ono, Yoshiaki*; Sato, Tatsuhiko; Kai, Takeshi
Nuclear Instruments and Methods in Physics Research B, 548, p.165231_1 - 165231_6, 2024/03
Times Cited Count：1 Percentile：63.95(Instruments & Instrumentation)One of the main causes of radiation effects on the human body is thought to be damage to DNA, which carries genetic information. However, it is not fully understood what kind of molecular structural changes DNA undergoes upon radiation damage. Since it has been reported that various types of DNA damage are formed when DNA is irradiated, our group has investigated the relationship between DNA damage and various patterns of radiation-induced ionization induced by radiation. Although we have so far analyzed DNA damage in a simple system using a rigid body model of DNA, more detailed calculations are required to analyze the molecular structural changes in DNA, which are considered to be important in considering the effects on the human body. In this study, we attempted to clarify the molecular conformational changes of DNA using OpenMX, a first-principles calculation software that can discuss electronic states based on molecular structures. Specifically, we calculated the most stable structure, band dispersion, and wave function of DNA under the assumption that one and two electrons are ionized by various radiation. In the presentation, we will discuss the relationship between the energy dependence of each incident radiation type and the molecular conformational change of DNA. In addition, the radiation-induced changes in the basic physical properties of DNA (corresponding to the initial stage of DNA damage) will be discussed from the viewpoints of both radiation physics and solid state physics.
Ho, H. Q.; Ishii, Toshiaki; Nagasumi, Satoru; Ono, Masato; Shimazaki, Yosuke; Ishitsuka, Etsuo; Sawahata, Hiroaki; Goto, Minoru; Simanullang, I. L.*; Fujimoto, Nozomu*; et al.
Nuclear Engineering and Design, 417, p.112795_1 - 112795_6, 2024/02
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)
inferred from muon studyKadono, Ryosuke*; Hiraishi, Masatoshi*; Okabe, Hirotaka*; Koda, Akihiro*; Ito, Takashi
Journal of Physics; Condensed Matter, 35(28), p.285503_1 - 285503_13, 2023/07
Times Cited Count：1 Percentile：12.10(Physics, Condensed Matter)
dynamics in the H conductors LaH
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Tamatsukuri, Hiromu; Fukui, Keiga*; Iimura, Soshi*; Honda, Takashi*; Tada, Tomofumi*; Murakami, Yoichi*; Yamaura, Junichi*; Kuramoto, Yoshio*; Sagayama, Hajime*; Yamada, Takeshi*; et al.
Physical Review B, 107(18), p.184114_1 - 184114_8, 2023/05
Times Cited Count：1 Percentile：14.50(Materials Science, Multidisciplinary)Yamamoto, Kazami; Kinsho, Michikazu; Hayashi, Naoki; Saha, P. K.; Tamura, Fumihiko; Yamamoto, Masanobu; Tani, Norio; Takayanagi, Tomohiro; Kamiya, Junichiro; Shobuda, Yoshihiro; et al.
Journal of Nuclear Science and Technology, 59(9), p.1174 - 1205, 2022/09
Times Cited Count：7 Percentile：75.64(Nuclear Science & Technology)In the Japan Proton Accelerator Research Complex, the purpose of the 3 GeV rapid cycling synchrotron (RCS) is to accelerate a 1 MW, high-intensity proton beam. To achieve beam operation at a repetition rate of 25 Hz at high intensities, the RCS was elaborately designed. After starting the RCS operation, we carefully verified the validity of its design and made certain improvements to establish a reliable operation at higher power as possible. Consequently, we demonstrated beam operation at a high power, namely, 1 MW. We then summarized the design, actual performance, and improvements of the RCS to achieve a 1 MW beam.
Kono, Takahiko; Tanaka, Masato*; Tanaka, Hitomi*; Shimo, Michikuni*; Torii, Hiroyuki*; Uno, Kazuko*
Journal of Radiation Protection and Research, 47(3), p.167 - 179, 2022/09
After the accident at the Fukushima Daiichi Nuclear Power Plant, artificial radionuclides such as radioactive cesium and iodine were released into the environment. It caused great anxiety not only in the vicinity of the Fukushima Daiichi Nuclear Power Plant but also in other regions of the world. Some members of the Japan Health Physics Society (JHPS), a leading academic society in Japan in the field of radiation protection, volunteered to establish a website called "Question and Answer about radiation in Daily Life" shortly after the accident to help reduce the residents anxiety about the health effects of radiation. In August 2011, Committee for "Question and Answer about radiation in Daily Life" was established in JHPS, making the website-related activities a responsibility of JHPS. The Q&A website continued to respond to the questions from the general public with expertise and sincerity until February 2013 when the Committee members decided to end the activities because the number of questions received had gradually decreased with the passage of time. This paper aims to introduce the following: the activities of the Q&A website during the two years (2011-2013), the stance chosen for the activities, the information related to the website activities and the analysis of Twitter data. Building on the experience and the knowledge obtained from the activities, it also discusses issues and experiences that can be utilized in the initial response to emergencies for radiation protection experts as well as other fields.
Ho, H. Q.; Ishii, Toshiaki; Nagasumi, Satoru; Ono, Masato; Shimazaki, Yosuke; Ishitsuka, Etsuo; Goto, Minoru; Simanullang, I. L.*; Fujimoto, Nozomu*; Iigaki, Kazuhiko
Nuclear Engineering and Design, 396, p.111913_1 - 111913_9, 2022/09
Times Cited Count：1 Percentile：15.53(Nuclear Science & Technology)Ohshima, Hiroyuki; Morishita, Masaki*; Aizawa, Kosuke; Ando, Masanori; Ashida, Takashi; Chikazawa, Yoshitaka; Doda, Norihiro; Enuma, Yasuhiro; Ezure, Toshiki; Fukano, Yoshitaka; et al.
Sodium-cooled Fast Reactors; JSME Series in Thermal and Nuclear Power Generation, Vol.3, 631 Pages, 2022/07
This book is a collection of the past experience of design, construction, and operation of two reactors, the latest knowledge and technology for SFR designs, and the future prospects of SFR development in Japan. It is intended to provide the perspective and the relevant knowledge to enable readers to become more familiar with SFR technology.
Sb
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F observed by high-resolution synchrotron and neutron diffractionShimono, Seiya*; Ishibashi, Hiroki*; Nagayoshi, Yusuke*; Ikeno, Hidekazu*; Kawaguchi, Shogo*; Hagihara, Masato; Torii, Shuki*; Kamiyama, Takashi*; Ichihashi, Katsuya*; Nishihara, Sadafumi*; et al.
Journal of Physics and Chemistry of Solids, 163, p.110568_1 - 110568_7, 2022/04
Times Cited Count：2 Percentile：15.11(Chemistry, Multidisciplinary)Shamoto, Shinichi*; Akatsu, Mitsuhiro*; Matsuura, Masato*; Kawamura, Seiko; Harii, Kazuya*; Ono, Masao*; Chang, L.-J.*; Ito, Takashi; Nemoto, Yuichi*; Ieda, Junichi
Physical Review Research (Internet), 4(1), p.013245_1 - 013245_7, 2022/03
Ultrasound injection effect on a magnetic Bragg peak of yttrium iron garnet has been studied by quasielastic neutron scattering. The magnetic Bragg peak is vastly enhanced with decreasing temperature. The energy width increases proportionally to the square root of the sample temperature increase induced by the ultrasound injection. Because the magnetic Bragg peak is enhanced by the lattice vibration, the enhancement is expected to relate to the spin-lattice coupling closely. An observed sharp drop above 100 K in the longitudinal mode suggests the degradation of the spin-lattice coupling. It is consistent with the decline of spin Seebeck effect with increasing temperature above 100 K, proving the degradation mechanism by the spin-lattice coupling.
Ono, Masato; Shimizu, Atsushi; Ohashi, Hirofumi; Hamamoto, Shimpei; Inoi, Hiroyuki; Tokuhara, Kazumi*; Nomoto, Yasunobu*; Shimazaki, Yosuke; Iigaki, Kazuhiko; Shinozaki, Masayuki
Nuclear Engineering and Design, 386, p.111585_1 - 111585_9, 2022/01
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)In the late 1980s during the design stage, the seismic classification of the high temperature engineering test reactor (HTTR) was formulated. Owing to the lack of operation experiences of the HTTR to sufficiently understand the safety characteristics of high temperature gas cooled reactors (HTGR) at that time, the seismic classification of commercial light water reactors (LWR) was applied to HTTR. However, the subsequent operation experiences and test results using HTTR made it clear that the seismic classification of commercial LWR was somewhat too conservative for the HTGR. As a result, Class S facilities were downgraded compared to the commercial LWR. Moreover, the validity of the new seismic classification is confirmed. In June 2020, the Nuclear Regulatory Authority approved that the result of the seismic classification conformed to the standard rules of the reactor installation change.
Hamamoto, Shimpei; Ohashi, Hirofumi; Iigaki, Kazuhiko; Shimazaki, Yosuke; Ono, Masato; Shimizu, Atsushi; Ishitsuka, Etsuo
Proceedings of 2021 International Congress on Advances in Nuclear Power Plants (ICAPP 2021) (USB Flash Drive), 6 Pages, 2021/10
Since the HTGR has a large amount of graphite material in the core, it is necessary to assume an accident in which the reactor pressure boundary is damaged and air flows into the core. It is important to state that at the time of this accident, graphite does not burn and the accident does not develop due to the heat of oxidation reaction. Therefore, in this study, in order to evaluate the combustibility of graphite materials, we propose a method to compare the calorific value and heat removal amount of the material. When calculating the calorific value, the structural material of HTTR, a high-temperature gas reactor in Japan, was used as a reference. The amount of air in contact with the structural material is a value determined from the chimney effect. The amount of heat release is the sum of convection and radiation. As a result of comparing the heat generation amount with the heat removal amount, it was shown that the heat release amount was always larger than the heat generation amount. This result shows that the graphite material does not depend on the state at the time of the air inflow accident, the temperature decreases and does not burn. It is important to clearly explain the non-flammability of graphite materials when deciding how to deal with severe accidents in HTGRs. This quantitative evaluation method based on a simple theory is considered useful.
Tochio, Daisuke; Nagasumi, Satoru; Inoi, Hiroyuki; Hamamoto, Shimpei; Ono, Masato; Kobayashi, Shoichi; Uesaka, Takahiro; Watanabe, Shuji; Saito, Kenji
JAEA-Technology 2021-014, 80 Pages, 2021/09
JAEA-Technology-2021-014.pdf:5.87MB
In response to the new regulatory standards established in response to the accident at TEPCO's Fukushima Daiichi Nuclear Power Station in March 2011, measures and impact assessments related to internal flooding at HTTR were carried out. In assessing the impact, considering the characteristics of the high-temperature gas-cooled reactor, flooding due to assumed damage to piping and equipment, flooding due to water discharge from the system installed to prevent the spread of fire, and flooding due to damage to piping and equipment due to an earthquake. The effects of submersion, flooding, and flooding due to steam were evaluated for each of them. The impact of the overflow of liquids containing radioactive materials outside the radiation-controlled area was also evaluated. As a result, it was confirmed that flooding generated at HTTR does not affect the safety function of the reactor facility by taking measures.
Okuma, Ryutaro*; Kofu, Maiko; Asai, Shinichiro*; Avdeev, M.*; Koda, Akihiro*; Okabe, Hirotaka*; Hiraishi, Masatoshi*; Takeshita, Soshi*; Kojima, Kenji*; Kadono, Ryosuke*; et al.
Nature Communications (Internet), 12, p.4382_1 - 4382_7, 2021/07
Times Cited Count：10 Percentile：62.51(Multidisciplinary Sciences)