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Tc separation/concentration technology from 
Mo by (n,
) method, 4Suematsu, Hisayuki*; Yang, Y.*; Ito, Akito*; Le, A. V.*; Su, Y.*; Kato, Suzuna*; Do, T. M. D.*; Suzuki, Tatsuya*; Osawa, Naoki*; Fujita, Yoshitaka; et al.
KURNS Progress Report 2025, P. 118, 2026/06
no abstracts in English
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
-molybdenum trioxide particles into waterYang, Y.*; Ngo, M. C.*; Kitagawa, Taiga*; Fujita, Yoshitaka; Takahashi, Yukiko*; Suzuki, Tatsuya*; Nakayama, Tadachika*; Do, T. M. D.*; Niihara, Koichi*; Suematsu, Hisayuki*
RSC Advances (Internet), 15(22), p.17222 - 17229, 2025/05
Times Cited Count：1 Percentile：0.00(Chemistry, Multidisciplinary)no abstracts in English
Mo adsorption; Utilizing spray-dried mesoporous alumina for clinical-grade generator developmentAlowasheeir, A.*; Eguchi, Miharu*; Fujita, Yoshitaka; Tsuchiya, Kunihiko; Wakabayashi, Ryutaro*; Kimura, Tatsuo*; Ariga, Katsuhiko*; Hatano, Kentaro*; Fukumitsu, Nobuyoshi*; Yamauchi, Yusuke*
Bulletin of the Chemical Society of Japan, 97(10), p.uoae099_1 - uoae099_7, 2024/10
Times Cited Count：10 Percentile：66.83(Chemistry, Multidisciplinary)no abstracts in English
Mo/
Tc radioisotope separation by modified extraction methodPratama, C.*; Fujita, Yoshitaka; Saptiama, I.*; Marlina, M.*; Triyatna, F.*; Ilhami, A.*; Maria, C. P.*; Tsuchiya, Kunihiko; Teguh, A.*; Prasetyo, I.*
Journal of Physics; Conference Series, 2828, p.012025_1 - 012025_12, 2024/10
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
Hu, X.*; Fujita, Yoshitaka; Tsuchiya, Kunihiko; Fukutani, Satoshi*; Hori, Junichi*; Suzuki, Tatsuya*
Journal of Radioanalytical and Nuclear Chemistry, 333(11), p.6057 - 6063, 2024/05
Times Cited Count：0 Percentile：0.00(Chemistry, Analytical)no abstracts in English
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.
Mo hot atoms made by a neutron capture method from 
-MoO
to waterQuach, 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：5 Percentile：61.58(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.
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.
-MoO whiskers in Mo/Tc radioisotope production and Mo/Tc extraction using hot atomsNgo, 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：6 Percentile：50.69(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.
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
Mo/Tc by PWRNasu, Takuya*; Fujita, Yoshitaka
Enerugi Rebyu, 42(10), p.15 - 18, 2022/09
no abstracts in English
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
Seki, Misaki; Fujita, Yoshitaka; Fujihara, Yasuyuki*; Zhang, J.*; Yoshinaga, Hisao*; Sano, Tadafumi*; Hori, Junichi*; Nagata, Hiroshi; Otsuka, Kaoru; Omori, Takazumi; et al.
Genshiryoku Bakkuendo Kenkyu (CD-ROM), 29(1), p.2 - 9, 2022/06
no abstracts in English
Fujita, Yoshitaka; Niizeki, Tomotake*; Fukumitsu, Nobuyoshi*; Ariga, Katsuhiko*; Yamauchi, Yusuke*; Malgras, V.*; Kaneti, Y. V.*; Liu, C.-H.*; Hatano, Kentaro*; Suematsu, Hisayuki*; et al.
Bulletin of the Chemical Society of Japan, 95(1), p.129 - 137, 2022/01
Times Cited Count：11 Percentile：52.54(Chemistry, Multidisciplinary)In this work, the mechanisms responsible for the adsorption of molybdate ions on alumina are investigated using in-depth surface analyses carried out on alumina specimens immersed in solutions containing different molybdate ions at different pH values. The obtained results reveal that when alumina is immersed in an acidic solution containing molybdate ions, the hydroxyl groups present on the surface are removed to generate positively charged sites, and molybdate ions (MoO
or AlMo
O
H
) are adsorbed by electrostatic interaction. Alumina dissolves slightly in an acidic solution to form AlMoOH, which is more easily desorbed than MoO. Furthermore, the enhancement in the Mo adsorption or desorption property may be achieved by enriching the surface of the alumina adsorbent with many -OH groups and optimizing Mo solution to adsorb molybdate ions on alumina as MoO ions. These findings will assist researchers in engineering more efficient and stable alumina-based adsorbents for molybdenum adsorption used in medical radioisotope (Mo/Tc) generators.
Mo adsorption and Tc elution with alumina columnsFujita, Yoshitaka; Seki, Misaki; Sano, Tadafumi*; Fujihara, Yasuyuki*; Suzuki, Tatsuya*; Yoshinaga, Hisao*; Hori, Junichi*; Suematsu, Hisayuki*; Tsuchiya, Kunihiko
Journal of Physics; Conference Series, 2155, p.012018_1 - 012018_6, 2022/01
Technetium-99m (Tc), the daughter nuclide of Molybdenum-99 (Mo), is the most commonly used radioisotope in radiopharmaceuticals. The research and development (R&D) for the production of Mo by the neutron activation method ((n, ) method) has been carried out from viewpoints of no-proliferation and nuclear security, etc. Since the specific activity of Mo produced by the (n, ) method is extremely low, developing AlO with a large Mo adsorption capacity is necessary to adapt (n, )Mo to the generator. In this study, three kinds of AlO specimens with different raw materials were prepared and compared their adaptability to generators by static and dynamic adsorption. MoO pellet pieces (1.5g) were irradiated with 5 MW for 20 min in the Kyoto University Research Reactor (KUR). Irradiated MoO pellet pieces were dissolved in 6M-NaOH aq. In dynamic adsorption, 1 g of AlO was filled into a PFA tube (
1.59 mm). The Mo adsorption capacity of AlO specimens under dynamic condition was slightly reduced compared to that under static condition. The Tc elution rate was about 100% at 1.5 mL of milking in dynamic adsorption, while it was around 56-87% in static adsorption. The Mo/Tc ratio of dynamic condition was greatly reduced compared to that of static condition. Therefore, the Tc elution property is greatly affected by the method of adsorbing Mo, e.g., the column shape, the linear flow rate, etc.
Mo/Tc generator by (n, ) method, 3Fujita, Yoshitaka; Seki, Misaki; Namekawa, Yoji*; Nishikata, Kaori; Daigo, Fumihisa; Ide, Hiroshi; Tsuchiya, Kunihiko; Sano, Tadafumi*; Fujihara, Yasuyuki*; Hori, Junichi*; et al.
KURNS Progress Report 2020, P. 136, 2021/08
no abstracts in English
Mo-adsorption/Tc-elution properties of alumina with different surface structuresFujita, Yoshitaka; Seki, Misaki; Sano, Tadafumi*; Fujihara, Yasuyuki*; Kitagawa, Tomoya*; Matsukura, Minoru*; Hori, Junichi*; Suzuki, Tatsuya*; Tsuchiya, Kunihiko
Journal of Radioanalytical and Nuclear Chemistry, 327(3), p.1355 - 1363, 2021/03
Times Cited Count：4 Percentile：32.90(Chemistry, Analytical)We prepared three types of AlO with different surface structures and investigated Mo-adsorption/Tc-elution properties using [Mo]MoO that was irradiated in the Kyoto University Research Reactor. AlO adsorbed [Mo]molybdate ions in solutions at different pH; the lower was the pH, the higher was the Mo-adsorption capacity of AlO. The Tc-elution properties of molybdate ion adsorbed AlO were elucidated by flowing saline. Consequently, it was suggested that Mo-adsorption/desorption properties are affected by the specific surface of AlO and Tc-elution properties are affected by the crystal structure of AlO.
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
