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Journal Articles

Study on $$^{99m}$$Tc separation/concentration technology from $$^{99}$$Mo by (n, $$gamma$$) 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

Journal Articles

Extraction of $$^{99}$$Mo hot atoms made by a neutron capture method from $$alpha$$-MoO$$_{3}$$ to water

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

https://doi.org/10.1007/s10967-023-09125-7
 Times Cited Count：4 Percentile：71.02(Chemistry, Analytical)

Technetium-99m ($$^{99m}$$Tc) is the most widely used medical radioisotope in the world and is produced from molybdenum-99 ($$^{99}$$Mo). Production of $$^{99}$$Mo via the neutron capture method draws attention as an alternative to fission-derived $$^{99}$$Mo due to non-proliferation issues, but the specific radioactivity of $$^{99}$$Mo is extremely low. In this work, a porous $$alpha$$-MoO$$_{3}$$ wire was prepared as an irradiation target in order to improve the specific activity by extracting $$^{99}$$Mo. Porous $$alpha$$-MoO$$_{3}$$ wire is synthesized from Mo metal wire by a two-step heating procedure. The hot atom effect of $$^{99}$$Mo was confirmed by activity and isotope measurements of the porous $$alpha$$-MoO$$_{3}$$ wire after neutron irradiation and the water used for extraction. In term of the extraction effectiveness, the effectiveness of $$^{99}$$Mo extraction in the porous $$alpha$$-MoO$$_{3}$$ wire was comparable to that of commercial $$alpha$$-MoO$$_{3}$$ powder.

Journal Articles

$$beta$$-MoO$$_{3}$$ whiskers in $$^{99}$$Mo/$$^{rm 99m}$$Tc radioisotope production and $$^{99}$$Mo/$$^{rm 99m}$$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
 Times Cited Count：5 Percentile：60.95(Chemistry, Inorganic & Nuclear)

Technetium-99m ($$^{rm 99m}$$Tc) is one of the most important radioisotopes for diagnostic radio-imaging applications. $$^{rm 99m}$$Tc is a daughter product of the $$^{99}$$Mo isotope. There are two methods used to produce $$^{99}$$Mo/$$^{rm 99m}$$Tc: the nuclear fission (n,f) and the neutron capture (n,$$gamma$$) 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,$$gamma$$) method is being developed as a future replacement for the (n,f) method. In this work, $$beta$$-MoO$$_{3}$$ whiskers prepared by the thermal evaporation method and $$alpha$$-MoO$$_{3}$$ particles were irradiated in a nuclear reactor to produce $$^{99}$$Mo/$$^{rm 99m}$$Tc via neutron capture. The irradiated targets were dispersed into water to extract the $$^{99}$$Mo/$$^{rm 99m}$$Tc. As a result, $$beta$$-MoO$$_{3}$$ whisker yielded higher $$^{99}$$Mo extraction rate than that from $$alpha$$-MoO$$_{3}$$. In addition, by comparing the dissolved $$^{98}$$Mo concentrations in water, we clarified a prominent hot-atom of $$beta$$-MoO$$_{3}$$ whiskers. This research is the first demonstration of $$beta$$-MoO$$_{3}$$ being used as an irradiation target in the neutron capture method. On the basis of the results, $$beta$$-MoO$$_{3}$$ is considered a promising irradiation target for producing $$^{99}$$Mo/$$^{rm 99m}$$Tc by neutron capture and using water for the radioisotope extraction process in the future.

Journal Articles

Study on $$^{rm 99m}$$Tc separation/concentration technology from $$^{99}$$Mo by (n, $$gamma$$) method

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

https://www.rri.kyoto-u.ac.jp/PUB/report/PR/ProgRep2022/ProgressReport2022.pdf#page=125

no abstracts in English

Journal Articles

Radiochemical research for the advancement of $$^{99}$$Mo/$$^{rm 99m}$$Tc generator by (n, $$gamma$$) 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

Journal Articles

Mechanisms responsible for adsorption of molybdate ions on alumina for the production of medical radioisotopes

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

https://doi.org/10.1246/bcsj.20210249
 Times Cited Count：10 Percentile：60.41(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$$_{4}$$$$^{2-}$$ or AlMo$$_{6}$$O$$_{24}$$H$$_{6}$$$$^{3-}$$) are adsorbed by electrostatic interaction. Alumina dissolves slightly in an acidic solution to form AlMo$$_{6}$$O$$_{24}$$H$$_{6}$$$$^{3-}$$, which is more easily desorbed than MoO$$_{4}$$$$^{2-}$$. 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$$_{4}$$$$^{2-}$$ ions. These findings will assist researchers in engineering more efficient and stable alumina-based adsorbents for molybdenum adsorption used in medical radioisotope ($$^{99}$$Mo/$$^{99m}$$Tc) generators.

Journal Articles

Dynamic properties on $$^{99}$$Mo adsorption and $$^{rm 99m}$$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 ($$^{rm 99m}$$Tc), the daughter nuclide of Molybdenum-99 ($$^{99}$$Mo), is the most commonly used radioisotope in radiopharmaceuticals. The research and development (R&D) for the production of $$^{99}$$Mo by the neutron activation method ((n, $$gamma$$) method) has been carried out from viewpoints of no-proliferation and nuclear security, etc. Since the specific activity of $$^{99}$$Mo produced by the (n, $$gamma$$) method is extremely low, developing Al$$_{2}$$O$$_{3}$$ with a large Mo adsorption capacity is necessary to adapt (n, $$gamma$$)$$^{99}$$Mo to the generator. In this study, three kinds of Al$$_{2}$$O$$_{3}$$ specimens with different raw materials were prepared and compared their adaptability to generators by static and dynamic adsorption. MoO$$_{3}$$ pellet pieces (1.5g) were irradiated with 5 MW for 20 min in the Kyoto University Research Reactor (KUR). Irradiated MoO$$_{3}$$ pellet pieces were dissolved in 6M-NaOH aq. In dynamic adsorption, 1 g of Al$$_{2}$$O$$_{3}$$ was filled into a PFA tube ($$phi$$1.59 mm). The $$^{99}$$Mo adsorption capacity of Al$$_{2}$$O$$_{3}$$ specimens under dynamic condition was slightly reduced compared to that under static condition. The $$^{rm 99m}$$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 $$^{99}$$Mo/$$^{rm 99m}$$Tc ratio of dynamic condition was greatly reduced compared to that of static condition. Therefore, the $$^{rm 99m}$$Tc elution property is greatly affected by the method of adsorbing Mo, e.g., the column shape, the linear flow rate, etc.

Journal Articles

Radiochemical research for the advancement of $$^{99}$$Mo/$$^{rm 99m}$$Tc generator by (n, $$gamma$$) method, 3

Fujita, 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

Journal Articles

Two-step-pressurization method in pulsed electric current sintering of MoO$$_{3}$$ for production of $$^{99m}$$Tc radioactive isotope

Suematsu, Hisayuki*; Sato, Soma*; Nakayama, Tadachika*; Suzuki, Tatsuya*; Niihara, Koichi*; Nanko, Makoto*; Tsuchiya, Kunihiko

Journal of Asian Ceramic Societies (Internet), 8(4), p.1154 - 1161, 2020/12

https://doi.org/10.1080/21870764.2020.1824326
 Times Cited Count：4 Percentile：17.02(Materials Science, Ceramics)

Pulsed electric current sintering of molybdenum trioxide (MoO$$_{3}$$) was carried out by one- and two-step pressuring methods for fabrication of irradiation target using production of $$^{99}$$Mo and $$^{rm 99m}$$Tc nuclear medicine. At 550$$^{circ}$$C by the two-step pressurizing method, a relative density of 93.1% was obtained while, by the one-step pressurization method, the relative density was 76.9%. Direct sample temperature measurements were conducted by inserting a thermocouple in a punch. By the two-step pressurizing method, the sample temperature was higher than that by the one-step pressurizing method even almost the same die temperature. From voltage and current waveforms, it was thought that the conductivity of the sample increased by the two-step pressurizing method to increase the sample temperature and the relative density. The two-step pressurization method enables us to prepare dense targets at a low temperature from recycled and coarse-grained $$^{98}$$Mo enriched MoO$$_{3}$$ powder.

Journal Articles

Radiochemical research for the advancement of $$^{99}$$Mo/$$^{rm 99m}$$Tc generator by (n,$$gamma$$) method, 2

Fujita, 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

https://www.rri.kyoto-u.ac.jp/PUB/report/PR/ProgRep2019/ProgressReport2019_online.pdf#page=173

no abstracts in English

Journal Articles

Preparation of potassium and metakaolin based geopolymer foam with millimeter sized open pores for hydrogen recombining catalyst supports

Utsumi, Taro*; Terasawa, Toshiharu*; Kudo, Isamu*; Suzuki, Tsuneo*; Nakayama, Tadachika*; Suematsu, Hisayuki*; Ogawa, Toru

Journal of the Ceramic Society of Japan, 128(2), p.96 - 100, 2020/02

https://doi.org/10.2109/jcersj2.19175
 Times Cited Count：5 Percentile：21.14(Materials Science, Ceramics)

A method to control the millimeter-sized open porosity in geopolymer foam was attempted to produce hydrogen recombining supports for radioactive waste canisters. The raw materials were mixed with silicon powder as a foaming agent. Geopolymer foams with open porosities as high as 81% were obtained by a water bath treatment before pouring the slurry into the mold. The increase in the open porosity of geopolymer foam was observed by an increase in the water bath treatment time. It was thought that the viscosity of slurry increase induced the pores trapped inside the geopolymer foam and connected to form millimeter-sized and open pores. It was concluded that a simple method with a foaming agent and a water bath treatment to prepare geopolymer foams with high open porosity was developed.

Journal Articles

Radiochemical research for the advancement of $$^{99}$$Mo/$$^{rm 99m}$$Tc generator by (n,$$gamma$$) method

Fujita, 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

https://www.rri.kyoto-u.ac.jp/PUB/report/PR/ProgRep2018/KURNS_Progress_Report2018_web.pdf

no abstracts in English

Journal Articles

Characterization of ZrN, ZrO$$_{2}$$ and $$beta$$'-Zr$$_{7}$$O$$_{11}$$N$$_{2}$$ nanoparticles synthesized by pulsed wire discharge

Lam, Do Van*; Suematsu, Hisayuki*; Ogawa, Toru

Journal of the American Ceramic Society, 100(10), p.4884 - 4892, 2017/10

https://doi.org/10.1111/jace.15012
 Times Cited Count：2 Percentile：9.25(Materials Science, Ceramics)

Nanoparticles of ZrN, ZrO$$_{2}$$ and ZrN, $$beta$$'-Zr$$_{7}$$O$$_{11}$$N$$_{2}$$ were synthesized by pulsed wire discharge. Morphology and phase analyses were carried out by X-ray diffraction and field-emission transmission electron microscopy (FE-TEM). By bright field image observation, electron energy loss spectroscopy (EELS) and selected area electron diffraction (SAD) analyses, those nanoparticles were separately characterized.

Oral presentation

Synthesis and characterization of cesium silicate Cs$$_{2}$$Si$$_{4}$$O$$_{9}$$

Do, Thi Mai Dung*; Ngarayana, I.*; Nguyen, H. D.*; Murakami, Kenta*; Suematsu, Hisayuki*; Koide, Manabu*; Nakajima, Kunihisa; Suzuki, Eriko; Osaka, Masahiko

no journal, , 

Cs$$_{2}$$Si$$_{4}$$O$$_{9}$$ powder was synthesized by wet method using cesium carbonate powder and colloidal silica 40 wt.% suspension in H$$_{2}$$O as starting materials. The characteristic of Cs$$_{2}$$Si$$_{4}$$O$$_{9}$$ is investigated by using X-ray diffraction, Raman and Thermogravimetry-differential scanning calorimetry. The structure of Cs$$_{2}$$Si$$_{4}$$O$$_{9}$$ was analyzed by Transmission Electron Microscope.

Oral presentation

Porosity control of multifunction geopolymer foam

Ogawa, Toru; Utsumi, Taro*; Terasawa, Toshiharu*; Kudo, Isamu*; Suzuki, Tsuneo*; Nakayama, Tadachika*; Suematsu, Hisayuki*

no journal, , 

For the fuel debris management, we develop the preparation techniques for highly porous geopolymer, which would be used as the matrix of neutron absorber as well as hydrogen recombiner. By adding silicon powder to the raw materials, and hot water in mixing, we demonstrated the capability to prepare geopolymer with high fractions of open pores.

Oral presentation

Pulsed electric current sintering of MoO$$_{3}$$ and the neutron irradiation tests

Suematsu, Hisayuki*; Seki, Misaki; Nakayama, Tadachika*; Nishikata, Kaori; Nanko, Makoto*; Suzuki, Tatsuya*; Tsuchiya, Kunihiko

no journal, , 

Pulsed electric current sintering (PECS) of MoO$$_{3}$$ was carried out for a high density target to produce $$^{99m}$$Tc from $$^{98}$$Mo in a nuclear reactor. The green compacts of MoO$$_{3}$$ were heated in a PECS apparatus with a heating rate of 100 $$^{circ}$$C/min to 450 - 550 $$^{circ}$$C in vacuum and changing the pressurization profile from 0 to 40 MPa. After two step pressurization for sintering at 550 $$^{circ}$$C, the sintered MoO$$_{3}$$ bulk had a relative density of 94%, which was higher than that of one step pressurization. Direct temperature measurements near the sample were carried out. The results indicated that the sample temperature was higher for the two step than for the one step pressurization even in the same die temperature experiments. By the low pressure in two step pressurization, it was thought that open pores remained in the sintered body to reduce MoO$$_{3}$$ in vacuum. This oxygen depleted MoO$$_{3-x}$$ grains showed low electrical resistivity and formed a current path in the sintered body to increase the temperature to increase the relative density.

Oral presentation

Reaction products in Cs-adsorption on concrete in the 600$$sim$$150$$^{circ}$$C temperature range

Do, Thi-Mai-Dung*; Nhut, V. L.*; Murakami, Kenta*; Suematsu, Hisayuki*; Nakajima, Kunihisa; Nishioka, Shunichiro; Suzuki, Eriko; Miradji, F.; Osaka, Masahiko

no journal, , 

The interaction between Cs$$_{2}$$MoO$$_{4}$$ with concrete within the temperature range of 600$$sim$$150$$^{circ}$$C in Ar gas is studied. It seems that there is no reaction between Cs$$_{2}$$MoO$$_{4}$$ aerosol particles with concrete at these temperatures. However, because of the hygroscopic property, Cs$$_{2}$$MoO$$_{4}$$ aerosol particles change to the liquid phase and quickly diffused inside the concrete bulk.

Oral presentation

Spark plasma sintering of MoO$$_{3}$$ for production of $$^{99m}$$Tc by neutron irradiation

Suematsu, Hisayuki*; Sato, Soma*; Nanko, Makoto*; Tsuchiya, Kunihiko; Nishikata, Kaori; Suzuki, Tsuneo*; Nakayama, Tadachika*; Niihara, Koichi*

no journal, , 

Spark plasma sintering of MoO$$_{3}$$ was carried out for production of $$^{99m}$$Tc from $$^{98}$$Mo by the (n,$$gamma$$) method in a nuclear reactor. Powder of MoO$$_{3}$$ with an average grain size of 0.8$$mu$$m and a purity of 99.99% was pressed in a graphite die with a diameter of 20 mm. Then, the green compact was heated in a spark plasma sintering apparatus with heating rates of 100 $$sim$$ 200$$^{circ}$$C/min to 500 $$sim$$ 600$$^{circ}$$C in vacuum. After holding the temperature for 5 min, the sample was quenched. The sintered samples were characterized by powder X-ray diffraction for phase identifications, electron energy loss spectroscopy for compositional analyses and scanning electron microscopy for grain size measurements. After sintering at 550$$^{circ}$$C, a sintered bulk of MoO$$_{3}$$ with a relative density of 98% was obtained. These properties are good enough for separation of $$^{99m}$$Tc and recycle of Mo.

Oral presentation

Sintering evaluation using coarse-grained MoO$$_{3}$$ powder for a radioisotope production

Sato, Soma*; Nanko, Makoto*; Suzuki, Tsuneo*; Nakayama, Tadachika*; Suematsu, Hisayuki*; Niihara, Koichi*; Tsuchiya, Kunihiko

no journal, , 

no abstracts in English

Oral presentation

Pulsed Electric Current Sintering of MoO$$_{3}$$ for Production of Radioactive Isotopes

Suematsu, Hisayuki*; Sato, Soma*; Seki, Misaki*; Nanko, Makoto*; Nishikata, Kaori; Suzuki, Yoshitaka; Tsuchiya, Kunihiko; Suzuki, Tsuneo*; Nakayama, Tadachika*; Niihara, Koichi*

no journal, , 

$$^{99m}$$Tc has been utilized as a radioactive isotope in medical applications. The majority of this isotope has been separated from nuclear fission products in testing reactors with highly enriched $$^{235}$$U fuel. However, these reactors have been shut down because of the age and the nuclear security reasons. On the other hand, a nuclear reaction method has been proposed. This method is to irradiate $$^{98}$$Mo by neutrons in a reactor to form $$^{98}$$Mo and then to decay to $$^{99m}$$Tc. As the target, MoO$$_{3}$$ pellets are required. However, because of the low evaporation temperature (700 $$^{circ}$$C) and coarse grain size of $$^{98}$$Mo enriched powder, it was difficult to obtain high density MoO$$_{3}$$ pellets. To overcome this problem, a two-step loading method in pulsed electric current sintering was carried out in this study.

24 (Records 1-20 displayed on this page)