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Ishijima, Yasuhiro; Kato, Chiaki; Motooka, Takafumi; Yamamoto, Masahiro; Kano, Yoichi*; Ebina, Tetsunari*
Materials Transactions, 54(6), p.1001 - 1005, 2013/06
Times Cited Count：7 Percentile：39.39(Materials Science, Multidisciplinary)Zirconium has been utilized in nuclear fuel reprocessing plants because of its superior corrosion resistance in nitric acid solutions. However, stress corrosion cracking (SCC) susceptibility of zirconium has been reported in boiling nitric acid solutions at the passivity breakdown potential. However, it has not been clear the SCC initiation and propagation behavior of zirconium. In this study, to clarify the SCC initiation and propagation behavior of zirconium, constant load tensile tests were carried out in boiling nitric acid solutions. From the results, many cracks were initiated under the oxide film and maximum crack led to rupture in the potentials that nobler than passivity breakdown potential. These results showed that the SCC of zirconium in boiling nitric acid solutions is due to the oxide formation. And this SCC behavior suggests that the SCC behavior of zirconium can be attributed to tarnish rupture model.
Ueno, Fumiyoshi; Uchiyama, Yohei*; Kato, Chiaki; Yamamoto, Masahiro; Ebina, Tetsunari*; Shimogawara, Shigeru*; Kano, Yoichi*
Nihon Genshiryoku Gakkai Wabun Rombunshi, 9(3), p.279 - 287, 2010/09
An application of cathodic protection method with impressed current system to control corrosion of austenitic stainless steel in boiling nitric acid solution was studied to improve corrosion resistance of components in fuel reprocessing plant. Plate and tube type specimens made of ultra low carbon type 304 stainless steel (SUS304ULC) were immersed in boiling nitric acid solutions using electrochemical test cells, electrochemical potentiostatic tests and cathodic protection tests were performed. Corrosion rates in the solution with and without protection were measured. As the results, corrosion rates of plate type specimens with cathodic protection were decreased from 1/40 to 1/10 against without protection. In the case of tube type specimen, loss of outer surface thickness was decreased about 1/8, and no deviation of the loss was observed. Authors were concluded that cathodic protection method was expectative as one of the maintenance methods of components in fuel reprocessing plant.
Yamamoto, Masahiro; Kato, Chiaki; Ishijima, Yasuhiro; Kano, Yoichi*; Ebina, Tetsunari*
no journal, ,
Zirconium had been used in nuclear fuel reprocessing plants, because of its superior corrosion resistance in nitric acid solution. However, stress corrosion cracking (SCC) was reported at highly concentrated nitric acid solution. In this report, electrochemical measurements were utilized to clarify the criteria of SCC occurrence of zirconium in boiling nitric acid solutions. For the relations between potentials and SCC susceptibilities, SCC behavior of zirconium was attributed to tarnish rupture model. The observations of fractured surfaces and cross sections of cracks also supported the validity of the model. SCC susceptibility of zirconium was mainly affected by the thick oxide film formation at the surface. In our whole observations, SCC of zirconium occurred only at transpassive regions. When a reprocessing plant made of zirconium operates in the passivity state, there is no SCC occurrence in the equipment.
Ishijima, Yasuhiro; Motooka, Takafumi; Kato, Chiaki; Yamamoto, Masahiro; Kano, Yoichi*; Ebina, Tetsunari*
no journal, ,
Zirconium has been utilized in reprocessing plant because of its superior corrosion resistance. But Stress corrosion cracking (SCC) susceptibility had been reported in some conditions. In order to clarify the SCC occurrence criteria of Zr in boiling nitric acid solution, constant load tests at potentiostatic condition were conducted. From the results, SCC of Zr in nitric acid solution occurred only at transpassive region. From the observation of intermediate samples, many cracks initiate under oxide film and then the maximum crack grown to rupture. If the reprocessing plant operates in the potential of passivity region, SCC of Zr will not occur.
Ishijima, Yasuhiro; Motooka, Takafumi; Kato, Chiaki; Yamamoto, Masahiro; Kano, Yoichi*; Ebina, Tetsunari*
no journal, ,
Zirconium has been utilized in reprocessing plant because of its superior corrosion resistance. But stress corrosion cracking (SCC) susceptibility had been reported in some conditions. In order to clarify the SCC occurrence criteria of Zr in boiling nitric acid solution, constant load tests at potentiostatic condition were conducted. From the results, SCC of Zr in nitric acid solution occurred only at transpassive region. And it is attributes to tarnish rupture model. From the observation of intermediate samples, many cracks initiate under oxide film and then the maximum crack has grown to rupture. If the reprocessing plant operates in the potential of passivity region, SCC of Zr will not occur.
Ueno, Fumiyoshi; Yamamoto, Masahiro; Kato, Chiaki; Tarui, Hirofumi; Ebina, Tetsunari*; Shimogawara, Shigeru*; Kano, Yoichi*
no journal, ,
An application of cathodic protection method with impressed current system to control corrosion of austenitic stainless steel in boiling nitric acid solution was studied to improve corrosion resistance of components in fuel reprocessing plant. Tube type specimens made of ultra low carbon type 304 stainless steel (SUS304ULC) were immersed in boiling nitric acid solutions using electrochemical test cells, electrochemical potentiostatic tests and cathodic protection tests were performed. Corrosion rates in the solution with and without protection were measured. As the results, loss of outer surface thickness of the tubes was decreased about 1/8, and no deviation of the loss was observed. Authors were concluded that cathodic protection method was expectative as one of the maintenance methods of components in fuel reprocessing plant.
Yamamoto, Masahiro; Ueno, Fumiyoshi; Kato, Chiaki; Tarui, Hirofumi; Ebina, Tetsunari*; Shimogawara, Shigeru*; Kano, Yoichi*
no journal, ,
In order to decrease corrosion rate of stainless steel in boiling nitric acid solution, cathodic protection method was attempted to utilize to reprocessing process. However, the effect of cathodic protection was confirmed in laboratory, there exist some evaluations of setups of electrodes and cathodic current densities. In this report, the calculation results of potentials and current density of cathodic protection conditions using low price scripted FEM software are introduced.
Kato, Chiaki; Soma, Yasutaka; Ueno, Fumiyoshi; Okada, Kiyotaka*; Ebina, Tetsunari*; Kano, Yoichi*; Nakayama, Jumpei
no journal, ,
no abstracts in English
Sugiyama, Hiroshi*; Okada, Kiyotaka*; Ebina, Tetsunari*; Kano, Yoichi*; Soma, Yasutaka; Kato, Chiaki; Ueno, Fumiyoshi; Nakayama, Jumpei*
no journal, ,
no abstracts in English
