Measurements of thermal conductivity for near stoichiometric (UPuAm)O (z = 0.05, 0.10, and 0.15)

Yokoyama, Keisuke; Watanabe, Masashi; Tokoro, Daishiro*; Sugimoto, Masatoshi*; Morimoto, Kyoichi; Kato, Masato; Hino, Tetsushi*

Nuclear Materials and Energy (Internet), 31, p.101156_1 - 101156_7, 2022/06

https://doi.org/10.1016/j.nme.2022.101156

In current nuclear fuel cycle systems, to reduce the amount of high-level radioactive waste, minor actinides (MAs) bearing MOX fuel is one option for burning MAs using fast reactor. However, the effects of Am content in fuel on thermal conductivity are unclear because there are no experimental data on thermal conductivity of high Am bearing MOX fuel. In this study, The thermal conductivities of near stoichiometric (UPuAm)O solid solutions(z = 0.05, 0.10, and 0.15) have been measured between room temperature (RT) and 1473 K. The thermal conductivities decreased with increasing Am content and satisfied the classical phonon transport model ((A+BT)) up to about 1473 K. A values increased linearly with increasing Am content because the change in ionic radius affects the conduction of the phonon due to the solid solution in U and Am. B values were independent of Am content.

structure observation of pyroelectric ceramics during power generation cycle

Kawasaki, Takuro; Fukuda, Tatsuo; Yamanaka, Satoru*; Sakamoto, Tomokazu*; Murayama, Ichiro*; Kato, Takanori*; Baba, Masaaki*; Hashimoto, Hideki*; Harjo, S.; Aizawa, Kazuya; et al.

Journal of Applied Physics, 131(13), p.134103_1 - 134103_7, 2022/04

https://doi.org/10.1063/5.0084166

Modeling and simulation of atmospheric corrosion of carbon steel considering environmental factor

Igarashi, Takahiro; Komatsu, Atsushi; Kato, Chiaki; Sakairi, Masatoshi*

Tetsu To Hagane, 107(12), p.998 - 1003, 2021/12

AA2020-0549.pdf:1.53MB

https://doi.org/10.2355/tetsutohagane.TETSU-2020-110

In order to clarify the effect of environmental factors on the amount of atmospheric corrosion of steel, novel model for predicting the reduction of atmospheric corrosion considering relative humidity and rain falls was developed. We conducted a one-year calculation simulation of atmospheric corrosion in Miyakojima City, Choshi City, and Tsukuba City using the developed model. Corrosion weight loss by the simulation could reproduce the measured value well. Corrosion weight loss at each point was greatly affected by the amount of flying sea salt, relative humidity, and rain falls.

Hydrogen absorption mechanism into iron in aqueous solution including metal cations by laser ablation tests and first-principles calculations

Igarashi, Takahiro; Otani, Kyohei; Kato, Chiaki; Sakairi, Masatoshi*; Togashi, Yusuke*; Baba, Kazuhiko*; Takagi, Shusaku*

ISIJ International, 61(4), p.1085 - 1090, 2021/04

https://doi.org/10.2355/isijinternational.ISIJINT-2020-065

In order to clarify the effect of metal cations (Zn, Mg, Na) in aqueous solution on hydrogen permeation into iron, the amount of hydrogen permeation from iron surface was measured by electrochemical tests with a laser ablation. Moreover, in order to obtain the basic mechanism of hydrogen permeation with metal cation, first-principles calculations were used to acquire the adsorption potential of the metal cation and the electronic state around iron surface. By Zn in solution, anodic reaction on ablated surface by laser irradiation was suppressed. Also, by quantum analysis Zn atoms were chemically bonded stronger than Na and Mg atoms to iron surface. It was suggested that the dissolution reaction of iron was suppressed by the formation of the Zn layer, and that lead suppression of hydrogen permeation into iron.

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

Effect of a raw material powder on sintered CeO pellets by 28 GHz microwave irradiation

Akashi, Masatoshi; Matsumoto, Taku; Kato, Masato

Transactions of the American Nuclear Society, 118, p.1391 - 1394, 2018/06

In this study, CeO pellet sintering by irradiating microwave at a frequency of 28 GHz was carried out to investigate the effect of particle diameter of raw powder on the density of sintered pellet. The highest bulk density is 94.2 %T.D. under the condition of 30 min holding at 1473 K. The bulk density decreases with increasing the particle diameter of used raw powder. On the other hand, all of the apparent density of sintered pellet is more than 93.5 %T.D.. The difference between the bulk density and the apparent density is caused by the difference of open porosity for each sample pellet. It seems that the high density sintered pellets with porous structure are obtained because sample pellet is heated internally and uniformly in microwave sintering.

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

http://doi.org/10.1002/adsu.201600020

no abstracts in English

Corrosion properties of Zircaloy-4 and M5 under simulated PWR water conditions

Shibata, Akira; Kato, Yoshiaki; Taguchi, Taketoshi; Futakawa, Masatoshi; Maekawa, Katsuhiro*

Nuclear Technology, 196(1), p.89 - 99, 2016/10

https://doi.org/10.13182/NT16-54

Cladding material Zircaloy-4 is gradually replaced by M5 (Zr-Nb alloy) and other new Nb added Zirconium alloys which are expected to have long operating life. Corrosion tests on Zircaloy-4 and M5 were performed in various hydrogen concentrations in water to research corrosion properties of those alloys. Specimens were exposed under PWR conditions. Increase of oxide layer was analysed by weight gain and observation. Electro chemical impedance spectroscopy was performed to compare corrosion properties. And effect of dissolved hydrogen concentration on increase of oxide layer of M5 is smaller than that of Zircaloy-4. M5 is less affected by local uniformity of dissolved hydrogen concentration and is more suitable as PWR fuel cladding. Results of Electro chemical spectroscopy shows that structural significant difference existed in oxidizing reaction of Zircaloy-4 and M5.

Review to give the public clear information on near surface disposal project of low-level radioactive wastes generated from research, industrial and medical facilities

Shobu, Nobuhiro; Kato, Masatoshi*; Takao, Tomoe*; Terashima, Daisuke*; Tanaka, Yoshie*; Shirasu, Hisanori*; Amazawa, Hiroya; Koibuchi, Hiroto; Nakata, Hisakazu

JAEA-Review 2013-028, 175 Pages, 2013/12

JAEA-Review-2013-028.pdf:10.13MB

JAEA has promoted near surface disposal project for low-level radioactive wastes generated from research, industrial and medical facilities. JAEA has carried out public information about the project. When some town meetings are held toward mutual understanding with the public more detailed and clear explanations for safety management of the project are needed especially. Therefore, the information provision method to make the public understand should be reviewed. Moreover, a survey should be carried out in order to get a sense of what the public knows, what it values and where it stands on nuclear energy and radiation issues, because the social environment surrounding nuclear energy and radiation issues has changed as a result of the accident at the Fukushima on March 11, 2011. This review clarified the points to keep in mind about public information on the project, and that public recognition or understanding toward nuclear energy and radiation was changed before and after the accident.

Melting temperature and thermal conductivities of corium prepared from UO and zircalloy-2

Kato, Masato; Uchida, Teppei; Hirooka, Shun; Akashi, Masatoshi; Komeno, Akira; Morimoto, Kyoichi

Materials Research Society Symposium Proceedings, Vol.1444, p.91 - 96, 2012/09

https://doi.org/10.1557/opl.2012.987