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Fujita, Natsuko; Miyake, Masayasu; Matsubara, Akihiro*; Ishii, Masahiro*; Watanabe, Takahiro; Jinno, Satoshi; Nishio, Tomohiro*; Ogawa, Yumi; Kimura, Kenji; Shimada, Akiomi; et al.
Dai-35-Kai Tandemu Kasokuki Oyobi Sono Shuhen Gijutsu No Kenkyukai Hokokushu, p.17 - 19, 2024/03
The JAEA-AMS-TONO facility at the Tono Geoscience Center, JAEA has three accelerator mass spectrometers. We report the present status of the JAEA-AMS-TONO.
Hirota, Noriaki; Nakano, Hiroko; Fujita, Yoshitaka; Takeuchi, Tomoaki; Tsuchiya, Kunihiko; Demura, Masahiko*; Kobayashi, Yoshinao*
The IV International Scientific Forum "Nuclear Science and Technologies"; AIP Conference Proceedings 3020, p.030007_1 - 030007_6, 2024/01
Dynamic strain aging (DSA) and intergranular stress corrosion cracking (intragranular SCC) occur in high temperature pressurized water simulating a boiling water reactor environment due to changes in dissolved oxygen (DO) content, respectively. In order to clearly understand the difference between these phenomena, the mechanism of their occurrence was summarized. As a result, it was found that DSA due to intragranular cracking occurred in SUS304 stainless steel at low DO 1 ppb, while DSA was suppressed at DO 100 to 8500 ppb due to the formation of oxide films on the surface. On the other hand, when DO was increased to 20000 ppb, the film was peeled from the matrix, O element diffused to the grain boundary of the matrix, resulting in intergranular SCC. These results are indicated that the optimum DO concentration must be adjusted to suppress crack initiation due to DSA and intergranular SCC.
Yokoyama, Hiroya; Maehara, Yushi; Fujita, Hiroki; Takada, Chie
KEK Proceedings 2023-2, p.126 - 131, 2023/11
no abstracts in English
Niwa, Masakazu; Shimada, Koji; Sueoka, Shigeru; Fujita, Natsuko; Yokoyama, Tatsunori; Ogita, Yasuhiro; Fukuda, Shoma; Nakajima, Toru; Kagami, Saya; Ogata, Manabu; et al.
JAEA-Review 2023-017, 27 Pages, 2023/10
This report is a plan of research and development (R&D) on geosphere stability for long-term isolation of high-level radioactive waste (HLW) in Japan Atomic Energy Agency (JAEA), in fiscal year 2023. The objectives and contents in fiscal year 2023 are described in detail based on the JAEA 4th Medium- and Long-term Plan (fiscal years 2022-2028). In addition, the background of this research is described from the necessity and the significance for site investigation and safety assessment, and the past progress. The plan framework is structured into the following categories: (1) Development and systematization of investigation techniques, (2) Development of models for long-term estimation and effective assessment, (3) Development of dating techniques.
Niwa, Masakazu; Shimada, Koji; Sueoka, Shigeru; Ishihara, Takanori; Ogawa, Hiroki; Hakoiwa, Hiroaki; Watanabe, Tsuyoshi; Nishiyama, Nariaki; Yokoyama, Tatsunori; Ogata, Manabu; et al.
JAEA-Research 2023-005, 78 Pages, 2023/10
This annual report documents the progress of research and development (R&D) in the 1st fiscal year of the Japan Atomic Energy Agency 4th Medium- and Long-term Plan (fiscal years 2022-2028) to provide the scientific base for assessing geosphere stability for long-term isolation of high-level radioactive waste. The plan framework is structured into the following categories: (1) Development and systematization of investigation techniques, (2) Development of models for long-term estimation and effective assessment, (3) Development of dating techniques. The current status of R&D activities with previous scientific and technological progress is summarized.
Quach, N. M.*; Ngo, M. C.*; Yang, Y.*; Nguyen, T. B.*; Nguyen, V. T.*; Fujita, Yoshitaka; Do, T. M. D.*; Nakayama, Tadachika*; Suzuki, Tatsuya*; Suematsu, Hisayuki*
Journal of Radioanalytical and Nuclear Chemistry, 332(10), p.4057 - 4064, 2023/10
Times Cited Count:0 Percentile:0.01(Chemistry, Analytical)Technetium-99m (Tc) is the most widely used medical radioisotope in the world and is produced from molybdenum-99 (Mo). Production of Mo via the neutron capture method draws attention as an alternative to fission-derived Mo due to non-proliferation issues, but the specific radioactivity of Mo is extremely low. In this work, a porous -MoO wire was prepared as an irradiation target in order to improve the specific activity by extracting Mo. Porous -MoO wire is synthesized from Mo metal wire by a two-step heating procedure. The hot atom effect of Mo was confirmed by activity and isotope measurements of the porous -MoO wire after neutron irradiation and the water used for extraction. In term of the extraction effectiveness, the effectiveness of Mo extraction in the porous -MoO wire was comparable to that of commercial -MoO powder.
Ikeda, Yoichi*; Umemoto, Yoshihiko*; Matsumura, Daiju; Tsuji, Takuya; Hashimoto, Yuki*; Kitazawa, Takafumi*; Fujita, Masaki*
Materials Transactions, 64(9), p.2254 - 2260, 2023/09
Times Cited Count:0Fujita, Yoshitaka
JAEA-Review 2023-010, 108 Pages, 2023/08
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 (AlO), 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.
Ngo, M. C.*; Fujita, Yoshitaka; Suzuki, Tatsuya*; Do, T. M. D.*; Seki, Misaki; Nakayama, Tadachika*; Niihara, Koichi*; Suematsu, Hisayuki*
Inorganic Chemistry, 62(32), p.13140 - 13147, 2023/08
Times Cited Count:0 Percentile:0.01(Chemistry, Inorganic & Nuclear)Technetium-99m (Tc) is one of the most important radioisotopes for diagnostic radio-imaging applications. Tc is a daughter product of the Mo isotope. There are two methods used to produce Mo/Tc: the nuclear fission (n,f) and the neutron capture (n,) methods. Between them, the (n,f) method is the main route, used for approximately 90% of the world's production. However, the (n,f) method faces numerous problems, including the use of highly enriched uranium, the release of highly radioactive waste, and nonproliferation problems. Therefore, the (n,) method is being developed as a future replacement for the (n,f) method. In this work, -MoO whiskers prepared by the thermal evaporation method and -MoO particles were irradiated in a nuclear reactor to produce Mo/Tc via neutron capture. The irradiated targets were dispersed into water to extract the Mo/Tc. As a result, -MoO whisker yielded higher Mo extraction rate than that from -MoO. In addition, by comparing the dissolved Mo concentrations in water, we clarified a prominent hot-atom of -MoO whiskers. This research is the first demonstration of -MoO being used as an irradiation target in the neutron capture method. On the basis of the results, -MoO is considered a promising irradiation target for producing Mo/Tc by neutron capture and using water for the radioisotope extraction process in the future.
Kitazawa, Takafumi; Ikeda, Yoichi*; Sakakibara, Toshiro*; Matsuo, Akira*; Shimizu, Yusei*; Tokunaga, Yo; Haga, Yoshinori; Kindo, Koichi*; Nambu, Yusuke*; Ikeuchi, Kazuhiko*; et al.
Physical Review B, 108(8), p.085105_1 - 085105_7, 2023/08
Fujita, 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
Kokubu, Yoko; Fujita, Natsuko; Watanabe, Takahiro; Matsubara, Akihiro; Ishizaka, Chika; Miyake, Masayasu*; Nishio, Tomohiro*; Kato, Motohisa*; Ogawa, Yumi*; Ishii, Masahiro*; et al.
Nuclear Instruments and Methods in Physics Research B, 539, p.68 - 72, 2023/06
Times Cited Count:0 Percentile:0.02(Instruments & Instrumentation)The JAEA-AMS-TONO facility at the Tono Geoscience Center, JAEA has an accelerator mass spectrometer (JAEA-AMS-TONO-5MV). The spectrometer enabled us to use a multi-nuclide AMS of carbon-14 (C), beryllium-10, aluminium-26 and iodine-129, and we have recently been proceeding test measurement of chlorine-36. In response to an increase of samples, we installed a state-of-the-art multi-nuclide AMS with a 300 kV Tandetron accelerator in 2020. Recently, we are driving the development of techniques of isobar separation in AMS and of sample preparation. Ion channeling is applied to remove isobaric interference and we are building a prototype AMS based on this technique for downsizing of AMS. The small sample graphitization for C has been attempted using an automated graphitization equipment equipped with an elemental analyzer.
Chen, Y.*; Asano, Shun*; Wang, T.*; Xie, P.*; Kitayama, Shinnosuke*; Ishii, Kenji*; Matsumura, Daiju; Tsuji, Takuya; Taniguchi, Takanori*; Fujita, Masaki*
JPS Conference Proceedings (Internet), 38, p.011050_1 - 011050_6, 2023/05
Matsubara, Akihiro*; Fujita, Natsuko; Miyake, Masayasu; Ishii, Masahiro*; Watanabe, Takahiro; Kokubu, Yoko; Nishio, Tomohiro*; Ogawa, Yumi; Jinno, Satoshi; Kimura, Kenji; et al.
JAEA-Conf 2022-002, p.55 - 62, 2023/03
We report the present status of the JAEA-AMS-TONO. Particularly, the destructions of varistors used in the beamline equipment will be presented. The cause of the destruction as well as implementation of the safety measures are mentioned.
Fujita, Natsuko; Miyake, Masayasu; Matsubara, Akihiro*; Ishii, Masahiro*; Watanabe, Takahiro; Jinno, Satoshi; Nishio, Tomohiro*; Ogawa, Yumi; Yamamoto, Yusuke; Kimura, Kenji; et al.
Dai-23-Kai AMS Shimpojiumu Hokokushu, p.1 - 4, 2022/12
The JAEA-AMS-TONO facility at the Tono Geoscience Center, JAEA has three accelerator mass spectrometers. We report the present status of the JAEA-AMS-TONO.
Jinno, Satoshi; Fujita, Natsuko; Tanuma, Hajime*
Dai-23-Kai AMS Shimpojiumu Hokokushu, p.89 - 92, 2022/12
The measurement of chlorine-36 (Cl) in AMS, which is important for the dating of saline groundwater, is more difficult than other nuclides due to the isobaric interference by sulfur-36 (S). In general, acceleration voltages of 6 MV or higher are required to separate Cl and S. Therefore, this study aims to develop an ion funnel reaction cell and incorporate it into the low energy side of JAEA-AMS-TONO-5MV to selectively suppress S.
Yasuoka, Yumi*; Fujita, Hiroki; Tsuji, Tomoya; Tsujiguchi, Takakiyo*; Sasaki, Michiya*; Miyazaki, Tomoyuki*; Hashima, Shun*; Yasuda, Hiroshi*; Shimada, Kazumasa; Hirota, Seiko*
Hoken Butsuri (Internet), 57(3), p.146 - 155, 2022/12
no abstracts in English
Fujita, Natsuko; Miyake, Masayasu*; Matsubara, Akihiro; Kokubu, Yoko; Klein, M.*; Scognamiglio, G.*; Mous, D. J. W.*; Columna, E. L.*; Shimada, Akiomi; Ishimaru, Tsuneari
Nuclear Instruments and Methods in Physics Research B, 533, p.91 - 95, 2022/12
Times Cited Count:1 Percentile:33.4(Instruments & Instrumentation)In the Tono Geoscience Center, Japan Atomic Energy Agency, investigation of deep underground environments for R&D program related to the geological disposal of High-Level Radioactive Waste has been performed by using various dating systems including an AMS system. In response to the increasing demand for our AMS measurements especially from a newly established R&D program supporting development of technology for geological disposal of HLW, a state-of-the-art multi-nuclide AMS system was installed. This system is equipped with a 300 kV AMS. The system has capability to measure four nuclides: carbon-14, beryllium-10, aluminium-26 and iodine-129. The system structure and features, as well as the results of performance test will be presented.
Fujita, Natsuko; Matsubara, Akihiro; Kimura, Kenji; Jinno, Satoshi; Kokubu, Yoko
Nuclear Instruments and Methods in Physics Research B, 532, p.13 - 18, 2022/12
Times Cited Count:1 Percentile:33.4(Instruments & Instrumentation)Over the last decade, significant technological advances were made to downsize the AMS systems. Japan Atomic Energy Agency has started a project for developing a prototype downsized AMS system (with the footprint of the system is 1.9 m 1.9 m) based on the surface stripper technique. Although the system configuration using an ion source, magnets, and detectors is similar to that in conventional systems, there is no tandem accelerator as well as a gas stripper. The ion acceleration is provided in the ion source (maximum ion energy 40 keV). For proof-of-principle experiments, we have planned two steps: (1) Observation of the specular reflection and the dissociation by using a compact electrostatic analyzer located just behind the stripper, and (2) Demonstration of C measurement, along with the experimental confirmation of the isobar suppression capability of the surface stripper.
Fujita, Manami; Hasegawa, Shoichi; Hosomi, Kenji; Ichikawa, Masaya; Ichikawa, Yudai; Kim, S.; Nanamura, Takuya; Sako, Hiroyuki; Tamura, Hirokazu; Yamamoto, Takeshi; et al.
Progress of Theoretical and Experimental Physics (Internet), 2022(12), p.123D01_1 - 123D01_17, 2022/12
Times Cited Count:0 Percentile:0.01(Physics, Multidisciplinary)