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Kano, Koichi*; Hagiwara, Satoshi*; Igarashi, Takahiro; Otani, Minoru*
Electrochimica Acta, 377, p.138121_1 - 138121_10, 2021/05
Times Cited Count：17 Percentile：71.29(Electrochemistry)We investigated the free corrosion potential at an interface between an Al electrode and an aqueous NaCl solution under acidic conditions via density functional theory combined with the effective screening medium and reference interaction site model (ESM-RISM). The electrode potentials for the anodic and cathodic corrosion reactions were obtained from the grand potential profile as a function of the electron chemical potential at the interface. Thereafter, we determined the free corrosion potential using the Tafel extrapolation method. The results of the free corrosion potential were consistent with previous experimental data. By controlling the pH, we determined the pH dependence of the free corrosion potential, and the results agreed well with the experimental results. Our results indicated that the ESM-RISM method duly described the environmental effect of an acidic solution and precisely determined the free corrosion potential.
Ueno, Fumiyoshi
Zairyo To Kankyo, 68(1), p.2 - 8, 2019/01
It is important to control the cooling water of light water reactors (boiling water reactor and pressurized water reactor) to suitable quality in order to reduce corrosion of structural materials and generation of radioactive corrosion products. For that purpose, monitoring of water quality using electrochemical measurement method is necessary. In this article, the application of ECP measurement to BWR is mainly focused, I describe the water quality of light water reactors and the necessity of electrochemical measurement.
Hanawa, Satoshi; Uchida, Shunsuke; Hata, Kuniki; Chimi, Yasuhiro; Kasahara, Shigeki*; Nishiyama, Yutaka
Proceedings of 20th Nuclear Plant Chemistry International Conference (NPC 2016) (USB Flash Drive), 11 Pages, 2016/10
ECP is the exclusive index to evaluate corrosion condition directly at the points of interest in the mixing of neutron and 
-ray environment. ECP can be calculated through the combination of water radiolysis and ECP model. A water radiolysis model have been applied to experiments performed in in-pile loops in the experimental reactors and applicability was confirmed. An ECP model based on the Butler-Volmer equation was also prepared. ECP of stainless steel was measured under well controlled water chemistry condition in in-pile loop in the Halden reactor, and the model was applied to evaluate ECP measured in the Halden reactor. The measured data were well explained by the water radiolysis calculation and ECP model. Accumulation of in-pile ECP data are expected for further validation of the models.
Kato, Chiaki; Sato, Tomonori; Ueno, Fumiyoshi; Yamagishi, Isao; Yamamoto, Masahiro
Zairyo To Kankyo 2015 Koenshu (CD-ROM), p.83 - 86, 2015/05
In relation to the consideration for long-term storage of spent Cs adsorption vessels containing zeolites in the Fukushima Daiichi Nuclear Power Station, corrosion of the vessel material in the spent Cs adsorption vessel is one of important issues. We performed electrochemical tests of stainless steel (SUS 316L) in the zeolites containing artificial seawater under gamma-ray irradiation. The spontaneous potential (ESP) and critical pitting potential (VC), of SUS316L were measured to understand the corrosion resistance of the stainless steel in this study. The rest potential of the stainless steel increased with increasing time after gamma-ray irradiation. The ESP, defined as the steady rest potential, increased with increasing dose rate, while increasing ESP was suppressed by contact with the zeolites. Concentration of H
O in bulk water increased with increasing dose rate. The concentration increasing was suppressed by contact with the zeolites due to decomposition of HO. There was good relationship between ESP and the concentration of HO. The VC of SUS316L contacted with the zeolites decreased with increasing Cl
ion concentration and is slightly smaller than the VC in the bulk water. The contact with the zeolites causes the suppressant of increasing ESP under the irradiation. The contact with the zeolites can reduce probability in the localized corrosion for SUS316L.
Tsukada, Takashi; Miwa, Yukio; Ugachi, Hirokazu; Matsui, Yoshinori; Itabashi, Yukio; Nagata, Nobuaki*; Dozaki, Koji*
Proceedings of International Conference on Water Chemistry of Nuclear Reactor Systems (CD-ROM), 5 Pages, 2004/10
IASCC initiation and propagation tests will be performed on the per-irradiated specimen in the Japan Materials Testing Reactor (JMTR). Since in core, the radiolysis of water causes a generation of various kind of radical species and some oxidizing species such as hydrogen peroxide, the water chemistry in irradiation capsules must be assessed by measurements of the electrochemical corrosion potential (ECP). For the in-core measurement of ECP in JMTR, we fabricated and tested the Fe/Fe
O
type ECP sensor. After the fabrication, the function of each sensor was examined in high temperature water by out-of-core thermal cycling and high temperature holding tests.
Shimogori, Kazutoshi*; Tomari, Haruo*; *; Fujiwara, Kazuo*; Masugata, Tsuyoshi*
PNC TJ1074 98-002, 270 Pages, 1998/02
None
Ishikawajima-Harima Heavy Industries*
PNC TJ1150 94-001, 19 Pages, 1994/03
None
-ray irradiationSato, Tomonori; Kato, Chiaki; Ueno, Fumiyoshi
no journal, ,
The structural materials of the instruments used in Fukushima Daiichi Nuclear Power Station are exposed to the corrosive condition under the -ray irradiation. In order to determine the effects of the temperature of water under -ray irradiation on the corrosion potential of stainless steel, the measurements of the corrosion potential under -ray irradiation condition was performed. The dissolved oxygen concentration was aerated condition in each temperature in this study. And the corrosive condition under the irradiation was evaluated by the water radiolysis calculation and the measurements of the included hydrogen peroxide in the water after the irradiation. As parameters, the temperature of water and the -ray dose rate were changed. The major results are listed as follows; (1) The corrosion potentials rose about 400 mV by the -ray irradiation in all temperature conditions. (2) The potential was low with higher temperature under irradiation with the aerated condition. It was assumed that the lower dissolved oxygen concentration with higher temperature will cause the dependency of the corrosion potential on the temperature under irradiation. (3) The generation of some ppm of hydrogen peroxide was confirmed by the measurements of hydrogen peroxide concentration. It was indicated that the increase of the corrosion potential by the irradiation was caused by the generation of the high concentration of hydrogen peroxide. (4) It was confirmed that the generation of hydrogen peroxide was lower in higher temperature condition due to the lower dissolved oxygen concentration in high temperature. It was indicated that lower potential in high temperature water was caused by not only lower dissolved oxygen but also lower generation of hydrogen peroxide.
Hata, Kuniki; Hanawa, Satoshi; Chimi, Yasuhiro; Uchida, Shunsuke
no journal, ,
no abstracts in English
Uchida, Shunsuke; Hata, Kuniki; Hanawa, Satoshi; Chimi, Yasuhiro
no journal, ,
no abstracts in English
Uchida, Shunsuke; Hata, Kuniki; Hanawa, Satoshi; Chimi, Yasuhiro
no journal, ,
The direct effects of hydrogen concentrations on the ECP were discussed in the previous presentation (the series #2). The parameters to determine ECP, e.g., pH and dose rate as well as hydrogen concentration, were different between in PWRs and BWRs. In the presentation, the direct and indirect effects of pH on ECP due to water radiolysis, surface properties and metallic ion solubilities are discussed. It was concluded that the corrosive conditions in the wide pH range which covered both PWR primary cooling water and BWR cooling water could be evaluated with a set of analysis codes for water radiolysis and ECP with applying the pH-dependent reaction constants.
Hata, Kuniki; Hanawa, Satoshi; Chimi, Yasuhiro; Uchida, Shunsuke
no journal, ,
no abstracts in English
Uchida, Shunsuke; Hata, Kuniki; Hanawa, Satoshi; Chimi, Yasuhiro
no journal, ,
In the previous presentations (the series No.1-4), it was confirmed that the water radiolysis and ECP models developed for BWR primary coolant conditions could be successfully applied for PWR primary coolant conditions. The coupled application of both models was applied to propose the optimal hydrogen concentration control from the viewpoint of ECP suppression. In the presentation, applicability of the models to evaluation of the boron and lithium simultaneous control was discussed and it was concluded that the optimal pH control for plant dose rate suppression and the optimal hydrogen concentration control for structural material integrity could be established at the same time.
/
/ radiation, 3; Effects of - and -ray radiation on corrosion; Electrochemical investigations using sealed beta sourceSato, Tomonori; Kato, Chiaki; Sato, Nobuaki*; Hata, Kuniki; Watanabe, Yutaka*
no journal, ,
Primary containment vessel in Fukushima Daiichi Nuclear Power Station is exposed to the corrosive environment under irradiation. Especially, the materials nearby the fuel debris will be exposed not only to gamma-ray but also to alpha- and beta-rays. However, the limited data were reported for the corrosion evaluations under the direct irradiation of alpha- and beta-rays. So, the electrochemical investigations were performed using sealed beta-ray source (Sr-90) in this study. As a result, it was confirmed that the polarization resistance of carbon steel decreased and the corrosion potential of stainless steel increased by beta-ray irradiation.
