Introduction to the simulation disaster challenge of world robot summit harsh environment F-REI challenge pre-tournament event

Nakamura, Keita*; Suzuki, Kenta; Kaneko, Eiichiro*; Abe, Yoshitaka*; Shimizu, Masaru*; Ogane, Katsuji*

Journal of Robotics and Mechatronics, 38(1), p.192 - 201, 2026/02

https://doi.org/10.20965/jrm.2026.p0192

Temperature and time dependence on extraction of Molybdenum-99 hot atoms from neutron-irradiated -molybdenum trioxide particles into water

Yang, 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

https://doi.org/10.1039/D5RA01952D

no abstracts in English

Study on Tc separation/concentration technology from Mo by (n, ) method, 2

Fujita, 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

Extraction of gold nanoparticles based on temperature-dependent phase separation using zwitterionic 3-(nonyldimethylammonio)-propyl sulfate

Nakagawa, Taichi; Suzuki, Reika*; Matsueda, Makoto; Terashima, Motoki; Hinze, W. L.*; Takagai, Yoshitaka*

Solvent Extraction Research and Development, Japan, 31(2), p.49 - 56, 2024/00

https://doi.org/10.15261/serdj.31.49

-MoO whiskers in Mo/Tc radioisotope production and Mo/Tc extraction using hot atoms

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

https://doi.org/10.1021/acs.inorgchem.3c02125

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.

Radiochemical research for the advancement of Mo/Tc generator by (n, ) method, 4

Fujita, 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

https://www.rri.kyoto-u.ac.jp/PUB/report/PR/ProgRep2021/ProgressReport2021_online.pdf#page=134

no abstracts in English

Dynamic properties on Mo adsorption and Tc elution with alumina columns

Fujita, 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

BB2021-0617.pdf:0.77MB

https://doi.org/10.1088/1742-6596/2155/1/012018

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.

Effect on Mo-adsorption/Tc-elution properties of alumina with different surface structures

Fujita, 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

AA2020-0805.pdf:0.77MB

https://doi.org/10.1007/s10967-021-07616-z

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.

Development and operation of an electrostatic time-of-flight detector for the Rare RI storage Ring

Nagae, Daisuke*; Abe, Yasushi*; Okada, Shunsuke*; Omika, Shuichiro*; Wakayama, Kiyoshi*; Hosoi, Shun*; Suzuki, Shinji*; Moriguchi, Tetsuro*; Amano, Masamichi*; Kamioka, Daiki*; et al.

Nuclear Instruments and Methods in Physics Research A, 986, p.164713_1 - 164713_7, 2021/01

https://doi.org/10.1016/j.nima.2020.164713

Comparative evaluation of response reliability during accidents in light water reactors and fast reactors

Suzuki, Masaaki*; Demachi, Kazuyuki*; Takaya, Shigeru; Chikazawa, Yoshitaka

Mechanical Engineering Journal (Internet), 7(4), p.19-00570_1 - 19-00570_11, 2020/08

https://doi.org/10.1299/mej.19-00570

To identify functions and facilities that are critical for ensuring safety in advanced reactors, for which only a limited usage history is available, it is necessary to consider the characteristics of each reactor type by utilizing more risk-related information. In this study, we compare the response capability during an accident for light water reactors and fast reactors to quantitatively evaluate the impact of the reactor type on resilience. A resilience evaluation procedure is developed for assessing the response margin and response reliability of a nuclear power plant during an accident; this procedure is then applied to a simple pressurized-water reactor and a sodium-cooled fast reactor plant model using an accident scenario involving an earthquake and leakage of coolant from the primary heat-transport system. Our research indicates a relatively large difference between the response reliability with respect to time for the two reactor types.