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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

 Times Cited Count:0 Percentile:0.01

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

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

 Times Cited Count:1 Percentile:17.37(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

Pyroelectric power generation with ferroelectrics (1-x)PMN-xPT

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:56.38(Materials Science, Multidisciplinary)

Journal Articles

Relationship between the material properties and pyroelectric-generating performance of PZTs

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

Journal Articles

Novel electrothermodynamic power generation

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:60.6(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 $textit{in-situ}$ synchrotron X-ray diffraction measurements under controlled conditions and $textit{Operando}$ 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$$^circ$$ domain switching extremely improves generating power, and the true energy breakeven with temperature variation is firstly achieved.

Journal Articles

The Self-regenerative "intelligent" catalyst for automotive emissions control

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

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

Two step pressurization in pulsed electric current sintering of MoO$$_{3}$$ for production of radioactive isotopes

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

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.

Oral presentation

Nuclide separation by water for development of $$^{99}$$Mo/$$^{99m}$$Tc generator for medical

Seki, Misaki*; Suematsu, Hisayuki*; Nakayama, Tadachika*; Suzuki, Tsuneo*; Niihara, Koichi*; Suzuki, Tatsuya*; Tsuchiya, Kunihiko; Duong Van, D.*

no journal, , 

no abstracts in English

Oral presentation

Isotope production using novel MoO$$_{3}$$ targets; Contribution by vietnamese institutes, staffs and students

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, $$^{99m}$$Tc has been widely used in gamma ray diagnoses. $$^{99}$$Mo, the raw material for $$^{99m}$$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 $$^{98}$$Mo(n,$$gamma$$)$$^{99}$$Mo reaction in low enriched uranium reactors can be an alternative method. In this research, we revealed that $$beta$$-MoO$$_{3}$$, a low-temperature phase of MoO$$_{3}$$, as a neutron irradiation target promotes the diffusion of $$^{99}$$Mo from the target to water due to the hot atom effect. Utilizing this phenomenon can contribute to the stable supply of $$^{99}$$Mo and $$^{99m}$$Tc. The first nuclear reaction in/water dispersion experiments using an $$alpha$$-MoO$$_{3}$$ 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 $$beta$$-MoO$$_{3}$$ whisker target by Vietnamese students and staffs. Their contributions to this research will be explained in the presentation.

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