-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.

Two-step-pressurization method in pulsed electric current sintering of MoO for production of 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

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 550C 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.

Electrical and crystallographic study of an electrothermodynamic cycle for a waste heat recovery

Kim, J.*; Yamanaka, Satoru*; Nakajima, Akira*; Kato, Takanori*; Kim, Y.*; Fukuda, Tatsuo; Yoshii, Kenji; Nishihata, Yasuo; Baba, Masaaki*; Takeda, Masatoshi*; et al.

Advanced Sustainable Systems (Internet), 2(11), p.1800067_1 - 1800067_8, 2018/11

https://doi.org/10.1002/adsu.201800067

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

https://doi.org/10.1080/00150193.2017.1349991

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

https://doi.org/10.1002/aenm.201401942

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.

Sintering evaluation using coarse-grained MoO 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

Pulsed Electric Current Sintering of MoO 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, , 

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.

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.

Isotope production using novel MoO 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, 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.