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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
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:4 Percentile:62.75(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.
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:5 Percentile:54.36(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.
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
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
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:10 Percentile:61.73(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 AlMo
O
H
, 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.
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
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 Al
O
with a large Mo adsorption capacity is necessary to adapt (n,
)
Mo to the generator. In this study, three kinds of Al
O
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 Al
O
was filled into a PFA tube (
1.59 mm). The
Mo adsorption capacity of Al
O
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.
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
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
Times Cited Count:4 Percentile:12.68(Materials Science, Ceramics)Pulsed electric current sintering of molybdenum trioxide (MoO) was carried out by one- and two-step pressuring methods for fabrication of irradiation target using production of
Mo and
Tc nuclear medicine. At 550
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
Mo enriched MoO
powder.
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
no abstracts in English
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
Times Cited Count:5 Percentile:21.60(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.
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
no abstracts in English
Lam, Do Van*; Suematsu, Hisayuki*; Ogawa, Toru
Journal of the American Ceramic Society, 100(10), p.4884 - 4892, 2017/10
Times Cited Count:2 Percentile:9.28(Materials Science, Ceramics)Nanoparticles of ZrN, ZrO and ZrN,
'-Zr
O
N
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.
Do, Thi Mai Dung*; Ngarayana, I.*; Nguyen, H. D.*; Murakami, Kenta*; Suematsu, Hisayuki*; Koide, Manabu*; Nakajima, Kunihisa; Suzuki, Eriko; Osaka, Masahiko
no journal, ,
CsSi
O
powder was synthesized by wet method using cesium carbonate powder and colloidal silica 40 wt.% suspension in H
O as starting materials. The characteristic of Cs
Si
O
is investigated by using X-ray diffraction, Raman and Thermogravimetry-differential scanning calorimetry. The structure of Cs
Si
O
was analyzed by Transmission Electron Microscope.
Suematsu, Hisayuki*; Seki, Misaki; Nakayama, Tadachika*; Nishikata, Kaori; Nanko, Makoto*; Suzuki, Tatsuya*; Tsuchiya, Kunihiko
no journal, ,
Pulsed electric current sintering (PECS) of MoO was carried out for a high density target to produce
Tc from
Mo in a nuclear reactor. The green compacts of MoO
were heated in a PECS apparatus with a heating rate of 100
C/min to 450 - 550
C in vacuum and changing the pressurization profile from 0 to 40 MPa. After two step pressurization for sintering at 550
C, the sintered MoO
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
in vacuum. This oxygen depleted MoO
grains showed low electrical resistivity and formed a current path in the sintered body to increase the temperature to increase the relative density.
Sato, Soma*; Nanko, Makoto*; Suzuki, Tsuneo*; Nakayama, Tadachika*; Suematsu, Hisayuki*; Niihara, Koichi*; Tsuchiya, Kunihiko
no journal, ,
no abstracts in English
Suematsu, Hisayuki*; Sato, Soma*; Nanko, Makoto*; Tsuchiya, Kunihiko; Nishikata, Kaori; Suzuki, Tsuneo*; Nakayama, Tadachika*; Niihara, Koichi*
no journal, ,
Spark plasma sintering of MoO was carried out for production of
Tc from
Mo by the (n,
) method in a nuclear reactor. Powder of MoO
with an average grain size of 0.8
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
200
C/min to 500
600
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
C, a sintered bulk of MoO
with a relative density of 98% was obtained. These properties are good enough for separation of
Tc and recycle of Mo.
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 CsMoO
with concrete within the temperature range of 600
150
C in Ar gas is studied. It seems that there is no reaction between Cs
MoO
aerosol particles with concrete at these temperatures. However, because of the hygroscopic property, Cs
MoO
aerosol particles change to the liquid phase and quickly diffused inside the concrete bulk.
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.
Seki, Misaki*; Suematsu, Hisayuki*; Nakayama, Tadachika*; Suzuki, Tsuneo*; Niihara, Koichi*; Suzuki, Tatsuya*; Tsuchiya, Kunihiko; Duong Van, D.*
no journal, ,
no abstracts in English