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Lai, W.-H.*; Wang, H.*; Zheng, L.*; Jiang, Q.*; Yan, Z.-C.*; Wang, L.*; Yoshikawa, Hirofumi*; Matsumura, Daiju; Sun, Q.*; Wang, Y.-X.*; et al.
Angewandte Chemie; International Edition, 59(49), p.22171 - 22178, 2020/12
Times Cited Count:79 Percentile:95.7(Chemistry, Multidisciplinary)Aoki, So; Taniguchi, Tomomi*; Sakai, Junichi*
Zairyo To Kankyo, 64(9), p.414 - 420, 2015/09
The objective of this study is to clarify the preferential dissolution mechanism of a duplex stainless steel (DSS) at its corrosion potential by means of in-situ Scanning Electrochemical Microscope observation. Probe electrode was fixed above ferritic and austenitic each phase of DSS at corrosion potential. Potential of the probe electrode was polarized toward noble direction, and probe current was measured. In a probe potential range of 0-0.70 V (SHE), anodic current due to hydrogen oxidation reaction could be detected. This anodic current was larger above austenitic phase than that above ferritic phase. In a probe potential range of 0.70-1.2 V, anodic current due to Fe oxidation reaction to Fe could be detected. This anodic current was larger above ferritic phase than that above austenitic phase. Based on these results, a preferential dissolution mechanism model of a DSS at the corrosion potential is proposed using internal polarization curves.
Machida, Masahiko; Nakamura, Hiroki; Srinivasan, S. G.*; Van Duin, A. C. T.*
Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 4 Pages, 2015/05
Zircalloy has been widely employed as an excellent material covering the fuel rod. The mechanical and thermal properties have been explored by various experiments. In terms of its use as the fuel cladding, its response to oxidation reactions is an important topic when it is exposed to high temperature and high pressure steam during severe accidents. Especially, the hydrogen production accompanied by the oxidation is critical because it can lead to the crisis of the hydrogen explosion, as observed in the Fukushima Nuclear Power Plant accidents. Silicon carbide (SiC) has been considered as an alternative cladding material owing to an advantage that hydrogen production is much suppressed in the equivalent condition compared to Zircalloy. Therefore, we simulate the oxidation reaction for both materials, i.e. Zirconium metal and SiC in atomistic level by using the ReaxFF reactive force field method to simulate the chemical reaction molecular dynamics. Through such comparative studies between Zirconium and SiC in the same condition, we clarify how the temperature and the steam pressure accelerates the oxidation reaction and the resultant hydrogen production in both materials at typical severe accident conditions. The advantage using ReaxFF is that it allows us to directly trace the oxygen diffusion inside the Zirconium metal and SiC depending on the temperature and vapor pressure together with the oxidation reaction. We can compare the reaction processes in both materials. Especially, we paid attention to the rate of hydrogen production in both materials.
Nagaishi, Ryuji; Morita, Keisuke; Yamagishi, Isao; Hino, Ryutaro; Ogawa, Toru
Proceedings of 2014 Nuclear Plant Chemistry Conference (NPC 2014) (USB Flash Drive), 9 Pages, 2014/10
Two years after Three Mile Island Unit 2 (TMI-2) loss-of-coolant accident, radioactive contaminated water has been processed by Submerged Demineralizer System (SDS) with two types of zeolite adsorbents to remove radioactive nuclides. During and after the process, adsorption amount and distribution of nuclides on the zeolites, residual water content and thermal conductivity in the SDS vessels have been measured or estimated for verification of safety in the process, subsequent transportation and disposal. Hydrogen generation has been also evaluated mainly by direct monitoring in the large-scale of vessel after the process. In this work, the revaluation of hydrogen generation was demonstrated on the basis of the open information of vessel, and the latest experimental data obtained in adsorption and radiolysis occurring in small-scale of zeolite-water mixtures. As a result, the evaluated data was found to be comparable with the reported data obtained in the large-scale of real vessel.
Taniguchi, Naoki; ; Kawasaki, Manabu*; Masugata, Tsuyoshi*
JNC TN8400 2001-001, 56 Pages, 2000/12
It is necessary to clear the effects of corrosion products on the corrosion life time of carbon steel overpack for geological isolation of high-level radioactive waste(HLW). Especially, it is important to understand the effects of magnetite because magnetite as a simulated corrosion product is reported to accelerate the corrosion rate of carbon steel. In this study, corrosion tests to reproduce the acceleration of corrosion due to magnetite was performed and the mechanism of the acceleration was investigated to evaluate the effects of magnetite as a corrosion product. Based on the results of experiments, following conclusions are obtained ; (1)Magnetite powder accelerates the corrosion rate of carbon steel. The main reaction of corrosion under the presence of magnetite is the reduction of Fe(III) in magnetite to Fe(II), but the reaction of hydrogen generation is also accelerated. The contribution of hydrogen generation reaction was estimated to be about 30% in the total corrosion reaction based on the experimental result of immersion test under the presence of magnetite. (2)Actual corrosion products containing magnetite generated by the corrosion of carbon steel protect the metal from the propagation of corrosion. The corrosion depth of carbon steel overpack due to magnetite was estimated to be about 1 mm based on the results of experiments. Even if the effect of magnetite is taken into the assessment of corrosion lifetime of overpack, total corrosion depth in 1000 years is estimated to be 33 mm, which is smaller than the corrosion allowance of 40 mm described in the second progress report on research and development for the geological disposal of HLM/ in Japan. It was concluded that the effect of magnetite on the corrosion life time of carbon steel overpack is negligible.
Akashi, Masatsune*; Fukaya, Yuichi*; Asano, Hidekazu*
JNC TJ8400 2000-015, 46 Pages, 2000/02
Difference of hydrogen generation phenomena on the surface of the Steels were not observed between carbon steel, atmospheric corrosion resisting steel and 5%-Ni steel. Rust layer was formed on these three-type of steels by steam oxidation method. And the chemical composition of the rust for the steels were basically two (2) layers structure for the previous two steels as hematite (FeO) based for the outer layer and magnetite (FeO) based for the inner layer. And for the last steel, it had three (3) layer in the rust as hematite (FeO) based for the outer layer, magnetite (FeO) based for the intermediate layer and Ni based layer for the inner layer. These steels showed mostly same Tafel gradient in their cathodic polarization curves compare with that for no rust specimens. However, the exchange current density which reaction is assumed as a hydrogen generation reaction was largely increased. The cathodic reaction for each steels whose surface is covered by magnetite layer might be accelerated, then the corrosion rate was considered as accelerated, too.
Akashi, Masatsune*; Fukaya, Yuichi*; Asano, Hidekazu*
JNC TJ8400 2000-014, 22 Pages, 2000/02
Difference of hydrogen generation phenomena on the surface of the Steels were not observed between carbon steel, atmospheric corrosion resisting steel and 5%-Ni steel. Rust layer was formed on these three-type of steels by steam oxidation method. And the chemical composition of the rust for the steels were basically two(2) layers structure for the previous two steels as hematite(FeO) based for the outer layer and magnetite(FeO) based for the inner layer. And for the last steel, it had three(3) layer in the rust as hematite(FeO) based for the outer layer, magnetite(FeO) based for the intermediate layer and Ni based layer for the inner layer. These steels showed mostly same Tafel gradient in their cathodic polarization curves compare with that for no rust specimens. However, the exchange current density which reaction is assumed as a hydrogen generation reaction was largely increased. The cathodic reaction for each steels whose surface is covered by magnetite layer might be accelerated, then the corrosion rate was considered as accelerated, too.
Shibata, Toshio*; *; *; Tsuru, Toru*; Inoue, Hiroyuki*
JNC TJ8400 2000-013, 38 Pages, 2000/02
None
Hashizume, Shuji; Matsumoto, Junko; Bamba, Tsunetaka
Genshiryoku Bakkuendo Kenkyu, 5(1), p.45 - 49, 1998/08
no abstracts in English
Miyata, Teijiro; Nakagiri, Naotaka*
Nihon Genshiryoku Gakkai-Shi, 39(12), p.1062 - 1068, 1997/00
Times Cited Count:4 Percentile:37.09(Nuclear Science & Technology)no abstracts in English
; Miyata, Teijiro
Nihon Genshiryoku Gakkai-Shi, 38(12), p.992 - 1000, 1996/00
Times Cited Count:1 Percentile:14.44(Nuclear Science & Technology)no abstracts in English
Hidaka, Akihide; Sugimoto, Jun; Soda, Kunihisa
EUR-14039-EN, p.28 - 36, 1992/00
no abstracts in English
Hidaka, Akihide; Sugimoto, Jun; *; Soda, Kunihisa
JAERI-M 89-213, 87 Pages, 1989/12
no abstracts in English
Saeki, Masakatsu
Kaku Yugoro, 19, p.6 - 10, 1987/00
no abstracts in English
*; *;
J.Electroanal.Chem., 197, p.331 - 340, 1986/00
Times Cited Count:7 Percentile:42.11(Chemistry, Analytical)no abstracts in English
Bulletin of the Chemical Society of Japan, 54(2), p.556 - 561, 1981/00
Times Cited Count:13 Percentile:65.72(Chemistry, Multidisciplinary)no abstracts in English