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Yokoyama, Kenichi*; Murata, Yusuke*; Shiimori, Fusae*; Sakai, Junichi*; Yamamoto, Masahiro; Uchiyama, Gunzo; Nojima, Yasuo*; Fujine, Sachio*
Fushoku Boshoku Kyokai Dai-58-Kai Zairyo To Kankyo Toronkai Koenshu, p.11 - 12, 2011/09
Characteristics of hydrogen embrittlement of pure Ti and Ti-5Ta alloys were evaluated by stress loading and constant load tests. Mechanical properties of these materials were affected by hydride formation of surface layers. Although elongation was reduced by hydrogen absorption, embrittlement was observed only in the surface hydride area. It is also suggested that Ti-5Ta alloy was better susceptibility of hydrogen embrittlement than pure Ti.
Miura, Tatsuya*; Nishikata, Atsushi*; Tsuru, Toru*; Yamamoto, Masahiro; Uchiyama, Gunzo; Nojima, Yasuo*; Fujine, Sachio*
Fushoku Boshoku Kyokai Dai-58-Kai Zairyo To Kankyo Toronkai Koenshu, p.15 - 16, 2011/09
There exist some equipments made of Ti or Ti-5Ta alloy in the spent nuclear fuel reprocessing plant. These equipments are investigated for failure by hydrogen embrittlement. To evaluate the stabilities of hydrogen in the solutions using at the reprocessing plant, channel-flow-ellectrode (CFE) method was utilized. The method to determine the dissolved hydrogen concentration was considered from the results of anodic polarization curves.
Kato, Chiaki; Motooka, Takafumi; Yamamoto, Masahiro
Fushoku Boshoku Kyokai Dai-58-Kai Zairyo To Kankyo Toronkai Koenshu, p.17 - 20, 2011/09
It is reported that high concentration NO
ion accelerated corrosion of stainless steel in nitric acid solutions including the high concentration nitrate due to reoxidation of oxidizability ions such as Cr(VI). The valence state of oxidizability ions in a boiling nitric acid aqueous solution was calculated quantitatively by developed thermodynamics model of boiling nitric acid solutions and comparison with the measured value and calculated value was conducted. As the applications of the thermodynamics model, the influence of the NO concentration in high concentration nitrate solutions accelerated re-oxidation of oxidizability ions such as Cr(VI) was investigated. As a result, optimized thermodynamics model of boiling nitric acid solutions is able to calculate REDOX potential of nitric acid solution and evaluate quantitatively the valence state of oxidizability ions in a boiling nitric acid aqueous solution.
Shiimori, Fusae*; Sakai, Junichi*; Yokoyama, Kenichi*; Motooka, Takafumi; Uchiyama, Gunzo; Nojima, Yasuo*; Fujine, Sachio*
Fushoku Boshoku Kyokai Dai-58-Kai Zairyo To Kankyo Toronkai Koenshu, p.13 - 14, 2011/09
In reprocessing plants, hydrogen gas was released by radiolysis of aqueous solution. The relationship of the amount of hydrogen gas and the amount of hydrogen absorption to titanium and Ti-5Ta were not clear. In this study, hydrogen was absorbed to titanium by the cathode charging and irradiation. Then, the amount of the hydrogen gas from solutions and the amount of the hydrogen absorbed to titanium was compared. It was found that a very small amount of the hydrogen by radiolysis was absorbed to titanium. It was suggested that the difference of the hydrogen absorption rate was caused by the difference of the hydrogen concentration on the metal surface.
Sato, Tomonori; Yamamoto, Masahiro; Kato, Chiaki; Tsukada, Takashi; Ogi, Hirokazu
Fushoku Boshoku Kyokai Dai-58-Kai Zairyo To Kankyo Toronkai Koenshu, p.185 - 188, 2011/09
The environmental factors for the corrosion of stainless steel were measured by the electrochemical impedance spectrometry in the high temperature pure water. And the analysis of the distribution of the flowing current between the electrodes was carried out to determine the cell factor for the impedance measurement system in this study and to determine the conductivity of the high temperature water more precisely. The current obtained theoretical analysis was 1.3 times larger than the current in the case that the cross section of the current path was equal to the area of the test specimen. The obtained conductivity relatively agreed with the literature data.