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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.
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:3 Percentile:16.14(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.
Kim, J.*; Yamanaka, Satoru*; Nakajima, Akira*; Kato, Takanori*; Kim, Y.*; Fukuda, Tatsuo; Yoshii, Kenji; Nishihata, Yasuo; Baba, Masaaki*; Takeda, Masatoshi*; et al.
Ferroelectrics, 512(1), p.92 - 99, 2017/08
Times Cited Count:14 Percentile:55.47(Materials Science, Multidisciplinary)Yamanaka, Satoru*; Kim, J.*; Nakajima, Akira*; Kato, Takanori*; Kim, Y.*; Fukuda, Tatsuo; Yoshii, Kenji; Nishihata, Yasuo; Baba, Masaaki*; Yamada, Noboru*; et al.
Advanced Sustainable Systems (Internet), 1(3-4), p.1600020_1 - 1600020_6, 2017/04
no abstracts in English
Kim, Y.*; Kim, J.*; Yamanaka, Satoru*; Nakajima, Akira*; Ogawa, Takashi*; Serizawa, Takeshi*; Tanaka, Hirohisa*; Baba, Masaaki*; Fukuda, Tatsuo; Yoshii, Kenji; et al.
Advanced Energy Materials, 5(13), p.1401942_1 - 1401942_6, 2015/07
Times Cited Count:18 Percentile:59.95(Chemistry, Physical)An innovative electro-thermodynamic cycle based on temporal temperature variations using pyroelectric effect has been presented. Practical energy is successfully generated in both synchrotron X-ray diffraction measurements under controlled conditions and
real engine dynamometer experiments. The main generating origin is revealed as a combination of a crystal structure change and dipole change phenomenon corresponds to the temperature variation. In particular, the electric field induced 180
domain switching extremely improves generating power, and the true energy breakeven with temperature variation is firstly achieved.
Tan, Isao*; Taniguchi, Masashi*; Tanaka, Hirohisa*; Uenishi, Mari*; Kajita, Nobuhiko*; Nishihata, Yasuo; Mizuki, Junichiro; Niihara, Koichi*
Key Engineering Materials, 317-318, p.833 - 836, 2006/08
no abstracts in English
Suematsu, Hisayuki*; Ngo, M. C.*; Quach, N. M.*; Fujita, Yoshitaka; Do, T. M. D.*; Nakayama, Tadachika*; Suzuki, Tatsuya*; Nguyen, V. T.*; Niihara, Koichi*
no journal, ,
Radiopharmacies have been used in various medical diagnoses/therapies and their market has been growing by ten times in fifteen years. In particular, Tc has been widely used in gamma ray diagnoses.
Mo, the raw material for
Tc, is currently produced as a fission product by irradiating highly enriched uranium in nuclear reactors. Efforts are being made worldwide to reduce the use of uranium from the perspective of nuclear non-proliferation. A
Mo(n,
)
Mo reaction in low enriched uranium reactors can be an alternative method. In this research, we revealed that
-MoO
, a low-temperature phase of MoO
, as a neutron irradiation target promotes the diffusion of
Mo from the target to water due to the hot atom effect. Utilizing this phenomenon can contribute to the stable supply of
Mo and
Tc. The first nuclear reaction in/water dispersion experiments using an
-MoO
powder target was carried out in Dalat Nuclear Reactor, Vietnam Atomic Energy Institute to show the hot atom effect. Then, the water recovery efficiency was dramatically improved using a novel
-MoO
whisker target by Vietnamese students and staffs. Their contributions to this research will be explained in the presentation.
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.
Suematsu, Hisayuki*; Seki, Misaki*; Sato, Soma*; Nanko, Makoto*; Tsuchiya, Kunihiko; Nishikata, Kaori; Suzuki, Tsuneo*; Nakayama, Tadachika*; Niihara, Koichi*
no journal, ,
no abstracts in English
Seki, Misaki*; Suematsu, Hisayuki*; Nakayama, Tadachika*; Suzuki, Tsuneo*; Niihara, Koichi*; Suzuki, Tatsuya*; Tsuchiya, Kunihiko; Duong Van, D.*
no journal, ,
no abstracts in English
Suematsu, Hisayuki*; Sato, Soma*; Seki, Misaki*; Nanko, Makoto*; Nishikata, Kaori; Suzuki, Yoshitaka; Tsuchiya, Kunihiko; Suzuki, Tsuneo*; Nakayama, Tadachika*; Niihara, Koichi*
no journal, ,
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
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
Mo by neutrons in a reactor to form
Mo and then to decay to
Tc. As the target, MoO
pellets are required. However, because of the low evaporation temperature (700
C) and coarse grain size of
Mo enriched powder, it was difficult to obtain high density MoO
pellets. To overcome this problem, a two-step loading method in pulsed electric current sintering was carried out in this study.
Sato, Soma*; Nanko, Makoto*; Suzuki, Tsuneo*; Nakayama, Tadachika*; Suematsu, Hisayuki*; Niihara, Koichi*; Tsuchiya, Kunihiko
no journal, ,
no abstracts in English