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Katsunuma, Yasushi*; Sato, Kaoru; Hasegawa, Takayuki*; Koba, Yusuke*
Radiological Physics and Technology, 14 Pages, 2025/12
In recent years, head CT scans have been used to diagnose subarachnoid hemorrhage, brain tumors, and head trauma. However, because the lens located in the head is at increased risk of cataracts due to radiation exposure, reducing radiation dose is a key challenge. Therefore, adjusting the angle of the gantry (the generator and detector of X ray) of the CT scanner has been used as a means of reducing lens dose. However, the specific angle and imaging range have not been defined in the protocol. In this study, we simulated the behavior of X rays emitted during head CT scans using the JF103 phantom and PHITS code developed by the JAEA, and analyzed the dose distribution in body. Our results quantitatively demonstrated that optimizing the gantry angle and imaging range can significantly reduce the lens dose. This finding will be important for revising protocols to optimize lens protection during head CT scans.
Iketani, Shotaro; Suzuki, Takeshi; Yokobori, Tomohiko; Sugawara, Satoshi; Yokota, Akira; Kikuchi, Genta; Muraguchi, Yoshinori; Kitahara, Masaru; Seya, Manato; Kurosawa, Tsuyoshi; et al.
JAEA-Technology 2025-001, 169 Pages, 2025/08
JAEA-Technology-2025-001.pdf:14.22MB
The radioactive waste treatment facilities at the Nuclear Science Research Institute includes the Radioactive Waste Treatment Facility No. 3, Waste Size Reduction and Storage Facility, and Waste Volume Reduction Facility. These three facilities come under the purview of the Act on the Regulation of Nuclear Source Material, Nuclear Fuel Material and Reactors, and are included under Class C of the act based on the seismic requirements specified in the Act. We assessed the seismic capacity of these three radioactive waste treatment facilities based on the current Building Standards Act, to verify whether they comply with the new regulatory requirements enforced by the Nuclear Regulation Authority (NRA) in the aftermath of the 2011 nuclear accident at the Fukushima Daiichi Nuclear Power Station operated by the Tokyo Electric Power Company. We found that the allowable stress of a few structural members used in the construction of the facilities did not meet the regulatory requirements. After studying the approval granted by the NRA for the construction plans, including the design and construction methods (design and construction plans) of the three facilities on March 5, 2021, we made aseismic reinforcement at these facilities between 2021 and 2022. This report presents an overview of the seismic design of these facilities and an outline of the aseismic reinforcement conducted, management system existing, safety measures adopted, and the preoperational inspections conducted at these facilities.
Murakami, Masashi; Yoshida, Yukihiko; Nango, Nobuhito*; Kubota, Shogo*; Kurosawa, Takuya*; Sasaki, Toshiki
Journal of Nuclear Science and Technology, 62(7), p.650 - 661, 2025/07
Times Cited Count：1 Percentile：68.76(Nuclear Science & Technology)
Tc separation/concentration technology from 
Mo by (n,
) method, 3Suematsu, Hisayuki*; Yang, Y.*; Kitagawa, Taiga*; Do, T. M. D.*; Suzuki, Tatsuya*; Fujita, Yoshitaka; Fujihara, Yasuyuki*; Yoshinaga, Hisao*; Hori, Junichi*
KURNS Progress Report 2024, P. 123, 2025/06
no abstracts in English
Saito, Shota; Kimura, Masanori; Hiraoka, Hirokazu
Kotsu Kogaku Kenkyu Happyokai Koenshu, 45, p.844 - 849, 2025/00
no abstracts in English
Tc separation/concentration technology from Mo by (n, ) method, 2Fujita, Yoshitaka; Hu, X.*; Yang, Y.*; Kitagawa, Taiga*; Fujihara, Yasuyuki*; Yoshinaga, Hisao*; Hori, Junichi*; Do, T. M. D.*; Suzuki, Tatsuya*; Suematsu, Hisayuki*; et al.
KURNS Progress Report 2023, P. 122, 2024/07
no abstracts in English
Maeda, Masaki*; Tanabe, Tadao*; Nishiwaki, Tomoya*; Aoki, Takayuki*; Dozaki, Koji*; Nishimura, Koshiro*; Fujii, Sho*; Ueno, Fumiyoshi; Tanaka, Akio*; Suzuki, Yusuke*; et al.
Transactions of the 27th International Conference on Structural Mechanics in Reactor Technology (SMiRT 27) (Internet), 10 Pages, 2024/03
Mo/Tc generators using the (n,) method (Thesis)Fujita, Yoshitaka
JAEA-Review 2023-010, 108 Pages, 2023/08
JAEA-Review-2023-010.pdf:6.62MB
Tc (technetium-99m) is the most widely used radioisotope in radiopharmaceutical and is decayed from the parent nuclide Mo (molybdenum-99). Most of Mo is generated as one of the fission products of uranium, but recently, from the viewpoint of nuclear security and nuclear nonproliferation, a uranium-free Mo production method is desired. One such method is the (n,) method, in which 
Mo is irradiated by neutrons. However, since the specific activity of Mo produced by this method is extremely low, it is necessary to improve the Mo adsorption and Tc elution property of alumina (Al
O
), which is used as a Mo adsorbent, to apply this method to the Mo/Tc generator, a device for separation and concentration of Tc from Mo. Therefore, the objective of this thesis is to elucidate the parameters effective for improving the performance of alumina for the practical use of the Mo/Tc generator using the (n,) method, and to contribute to the development of alumina columns that may be applicable to low specific activity Mo. In this study, alumina with different starting materials was prepared and its applicability as Mo adsorbent for Mo/Tc generator was evaluated. The effects of crystal structure and specific surface area of alumina on Mo adsorption properties were clarified, and the Mo adsorption mechanism was elucidated based on the results of surface analysis of alumina. In addition, Tc elution properties and Tc solution quality were evaluated using MoO irradiated in the Kyoto University Research Reactor (KUR), and a new column shape with potential application to generators was proposed based on the experiment results of alumina columns designed for current generators.
Tc separation/concentration technology from Mo by (n, ) methodFujita, Yoshitaka; Hu, X.*; Takeuchi, Tomoaki; Takeda, Ryoma; Fujihara, Yasuyuki*; Yoshinaga, Hisao*; Hori, Junichi*; Suzuki, Tatsuya*; Suematsu, Hisayuki*; Ide, Hiroshi
KURNS Progress Report 2022, P. 110, 2023/07
no abstracts in English
Hiraoka, Hirokazu; Komatsuzaki, Joji*; Hanaka, Norihiko*; Okamoto, Akiko; Saito, Yoshihiko*; Munakata, Masahiro; Togawa, Orihiko
JAEA-Technology 2022-003, 70 Pages, 2022/07
JAEA-Technology-2022-003.pdf:2.53MB
In contamination inspections for public in nuclear emergency, it is assumed that a large number of motor vehicles and evacuees will be inspected. At present, first measurement points of vehicles are tires and around a wiper, and they are basically inspected by persons using portable radiation surface contamination meters such as GM survey meters. However, in order to efficiently inspect contamination of vehicles, utilization of portable radiation portal monitors is being considered for the inspection. In this study, examination of performance of the portal monitor was conducted in order to obtain basic data. In this examinations, sealed radiation sources, 
Ba, were substituted for the contamination of Operational Intervention Level 4 (OIL4), the evaluation criteria to conduct simple decontamination in the contamination inspection. The radiation source was attached practically to a tire and around the wipers of a vehicle, and the counting rate of -rays from the radiation sources was measured using the portal monitor. Three examinations were conducted: static examination with a vehicle stationary, moving examination to mock the actual inspection, and high back ground examination to investigate performance of the equipment in high back ground environment. The vehicle mainly used in the experiments was a sedan, which is generally used as standard vehicles. And, a van whose front body is like that of a bus was used at this experiment. In addition, the "Gamma Pole" manufactured by the Chiyoda Technol Corporation was used as the portal monitor. As the result, it was estimated that the case of contamination equivalent to 40,000 cpm, the default value of the OIL4, deposited on the tread on a vehicle tire, when the vehicle passes through the portal monitor at 10 km/h or less, the contamination would be detected with a probability of 99% or more. Similarly, when the contamination deposited on around the wipers and the vehicle speed is 5 km/h or less,
Mo/Tc generator by (n, ) method, 4Fujita, Yoshitaka; Seki, Misaki; Ngo, M. C.*; Do, T. M. D.*; Hu, X.*; Yang, Y.*; Takeuchi, Tomoaki; Nakano, Hiroko; Fujihara, Yasuyuki*; Yoshinaga, Hisao*; et al.
KURNS Progress Report 2021, P. 118, 2022/07
no abstracts in English
Takeyasu, Masanori; Fujiwara, Kenso
JAEA-Review 2021-061, 11 Pages, 2022/03
JAEA-Review-2021-061.pdf:1.78MB
Internal dose examination by whole body counter (WBC) for the Fukushima residents (hereinafter referred to as "Fukushima WBC examination") is being conducted by the Fukushima Prefecture. The Japan Atomic Energy Agency has cooperated continually from the starting of the Fukushima WBC examination. In this paper, the Fukushima WBC examination were reviewed such as the results of the examination and the correspondence to the questions from the residents. Also, as a reference, the results of examinations were shown which were conducted by the other organizations and opened to the public.
Project 6 Meeting Members for Tsukuba International Strategic Zone
JAEA-Review 2021-016, 102 Pages, 2021/11
JAEA-Review-2021-016.pdf:12.76MB
In December 2011, the Prime Minister designated Tsukuba and some areas in Ibaraki Prefecture as "Comprehensive Special Zones". In the Tsukuba International Strategic Zone, nine advanced research and development (R&D) projects are underway with the goal of promoting industrialization of life innovation and green innovation utilizing the science and technology in Tsukuba. In these projects, the domestic production of medical radioisotope (Technetium-99m, Tc) was certified as a new project in October 2013, and R&D have been performed in collaboration with related organizations with Japan Atomic Energy Agency (JAEA) as the project leader. Japan is the third largest consumer of molybdenum-99 (Mo) after the United States and Europe, and all Mo are imported. Supply will be insufficient if overseas reactors are shut down due to trouble or if transportation (air and land transportations) is stopped due to volcanic eruptions and some accidents. Thus, early domestic production of Mo is strongly required. This project is a technology development aimed at domestic production of Mo, which is a raw material of Tc used as a diagnostic agent. This report summarizes the activities carried out in the first and second phase of the domestic production of medical radioisotope (Tc) (here referred to as the "Project 6") in Tsukuba International Strategic Zone (FY2014-2020).
Mo/Tc generator by (n,) method, 2Fujita, Yoshitaka; Seki, Misaki; Namekawa, Yoji*; Nishikata, Kaori; Kato, Yoshiaki; Sayato, Natsuki; Tsuchiya, Kunihiko; Sano, Tadafumi*; Fujihara, Yasuyuki*; Hori, Junichi*; et al.
KURNS Progress Report 2019, P. 157, 2020/08
no abstracts in English
Katsuyama, Jinya; Miyamoto, Yuhei*; Lu, K.; Mano, Akihiro; Li, Y.
Proceedings of ASME 2020 Pressure Vessels and Piping Conference (PVP 2020) (Internet), 8 Pages, 2020/08
We have developed a probabilistic fracture mechanics (PFM) analysis code PASCAL4 for evaluating failure frequency of reactor pressure vessels (RPVs). It is known that flaw distributions have an important role in failure frequency calculation in PFM analysis. Previously, we proposed likelihood function to obtain more realistic flaw distributions applicable for both case when flaws are detected and when there is no flaw indication as the inspection results based on Bayesian update methodology. Here, it can be applied to independently obtain posterior distributions of flaw depth and density. In this study, we improve the likelihood function to enable them to update flaw depth and density simultaneously. Based on the improved likelihood function, an example is presented in which flaw distributions are estimated by reflecting NDI results through Bayesian update and PFM analysis. The results indicate that the improved likelihood functions are useful for estimating flaw distributions.
Wakui, Takashi; Wakai, Eiichi; Kogawa, Hiroyuki; Naoe, Takashi; Hanano, Kohei; Haga, Katsuhiro; Takada, Hiroshi; Shimada, Tsubasa*; Kanomata, Kenichi*
JPS Conference Proceedings (Internet), 28, p.081002_1 - 081002_6, 2020/02
A mercury target vessel of J-PRAC is designed with a triple-walled structure consisting of the mercury vessel and a double-walled water shroud with internal and external vessels. During the beam operation at 500 kW in 2015, small water leakages from a water shroud of the mercury target vessel occurred twice. Design, fabrication and inspection processes were improved based on the lessons learned from the target failures. The total length of welding lines at the front of the mercury target vessel decreases drastically to approximately 55% by adopting monolithic structure cut out from a block of stainless steel by the wire-electrical discharge machining. Thorough testing of welds by radiographic testing and ultrasonic testing was conducted. The fabrication of the mercury target vessel #8 was finished on September 2017 and the beam operation using it started. Stable beam operation at 500 kW has been achieved and it could experience the maximum beam power of 1 MW during a beam test.
Mo/Tc generator by (n,) methodFujita, Yoshitaka; Seki, Misaki; Namekawa, Yoji*; Nishikata, Kaori; Kimura, Akihiro; Shibata, Akira; Sayato, Natsuki; Tsuchiya, Kunihiko; Sano, Tadafumi*; Fujihara, Yasuyuki*; et al.
KURNS Progress Report 2018, P. 155, 2019/08
no abstracts in English
Fukumitsu, Nobuyoshi*; Yamauchi, Yusuke*; Saptiama, I.*; Ariga, Katsuhiko*; Hatano, Kentaro*; Kumada, Hiroaki*; Fujita, Yoshitaka; Tsuchiya, Kunihiko
Isotope News, (760), p.15 - 18, 2018/12
no abstracts in English
pellets for Mo-99 productionFujita, Yoshitaka; Nishikata, Kaori; Namekawa, Yoji*; Kimura, Akihiro; Shibata, Akira; Sayato, Natsuki; Tsuchiya, Kunihiko; Sano, Tadafumi*; Fujihara, Yasuyuki*; Zhang, J.*
KURRI Progress Report 2017, P. 126, 2018/08
no abstracts in English
pellets for Mo-99 production, 3Ishida, Takuya; Suzuki, Yoshitaka; Nishikata, Kaori; Yonekawa, Minoru; Kato, Yoshiaki; Shibata, Akira; Kimura, Akihiro; Matsui, Yoshinori; Tsuchiya, Kunihiko; Sano, Tadafumi*; et al.
KURRI Progress Report 2015, P. 64, 2016/08
no abstracts in English
