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for production of 
Tc radioactive isotopeSuematsu, 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：17(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.
Kurata, Masaki; Nakamura, Kinya*; Yamada, Wataru*; Koyama, Toshiyuki*; Takaki, Tomohiro*; Nanko, Makoto*; Tokunaga, Tatsuya*
no journal, ,
A METI project is ongoing to develop multi scale and multi physics models and databases for elucidating fuel degradation mechanism in severe accident under collaboration among JAEA, CRIEPI, NSSMC, and universities. In JFY2012, technology investigation and model calculation were performed. Base MPFM was developed to study liquefaction condition in mesoscale. Combination between VOF and FLUENT shows high technical potential to simulate candling. A copling among VOF, FLUENT and MARC shows the high technical potential to simulate real scale fuel assembly degradation. As for thermodynamic database, various concerns were extracted from model calculation using conventional database like NUCLEA. In the project, not only developing models and databases but also constructing test facilities are planned. In JFY2012, preliminal tests were performed using conventional test apparatuses and basic concepts for three test facilities to be developed were extracted.
Kurata, Masaki; Nakamura, Kinya*; Tanaka, Masahiro*; Koyama, Toshiyuki*; Takaki, Tomohiro*; Tokunaga, Tatsuya*; Nanko, Makoto*
no journal, ,
The outline and the present status of METI project entitled Advanced Multi-scale Modeling and Experimental Tests on Fuel Degradation in Severe Accident Condition are overviewed.
for production of Tc by neutron irradiationSuematsu, 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 
200C/min to 500 600C 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 550C, 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.
powder for a radioisotope productionSato, Soma*; Nanko, Makoto*; Suzuki, Tsuneo*; Nakayama, Tadachika*; Suematsu, Hisayuki*; Niihara, Koichi*; Tsuchiya, Kunihiko
no journal, ,
no abstracts in English
for production of radioactive isotopesSuematsu, Hisayuki*; Seki, Misaki*; Sato, Soma*; Nanko, Makoto*; Tsuchiya, Kunihiko; Nishikata, Kaori; Suzuki, Tsuneo*; Nakayama, Tadachika*; Niihara, Koichi*
no journal, ,
no abstracts in English
C at elevated temperaturesPham, V. H.; Matsuura, Suguru*; Nanko, Makoto*; Nagae, Yuji; Kurata, Masaki
no journal, ,
for Production of Radioactive IsotopesSuematsu, 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.
and the neutron irradiation testsSuematsu, 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.
scale on fuel tube cladding by the melt of control rod assembleNakajima, Shotaro*; Matsuura, Suguru*; Nanko, Makoto*; Kurata, Masaki; Pham, V. H.
no journal, ,
scale formed on zircaloy in steam starvation conditionsNakajima, Shotaro*; Matsuura, Suguru*; Nanko, Makoto*; Kurata, Masaki; Pham, V. H.
no journal, ,
no abstracts in English
