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Kawai, Keito*; Nemoto, Yoshiyuki; Fujimura, Yuki; Kondo, Keietsu; Abe, Yosuke; Mohamad, A. B.; Pham, V. H.; Ishikawa, Norito; Ishijima, Yasuhiro; Ioka, Ikuo; et al.
Nihon Genshiryoku Gakkai Wabun Rombunshi (Internet), 24(3), p.82 - 98, 2025/08
An accident tolerant fuel (ATF) cladding, which is more resistant to accidents than the conventional Zircaloy cladding, is under development. One of these claddings is a chromium (Cr)-coated cladding with an outer surface coated with Cr, which is expected to improve the resistance to high-temperature steam oxidation. In this study, electrochemical plating was applied to coat a Cr layer on the cladding outer surface, and its properties under accidental conditions were evaluated. In a loss-of-coolant accident (LOCA), the cladding will burst and both the outer and inner surfaces of the cladding will be oxidized. Thus, as-received Zircaloy-4 and Cr-coated claddings were tested for oxidation in high-temperature steam to investigate differences in oxidation behavior, hydrogen absorption behavior, and mechanical properties after oxidation. Oxidation tests were conducted using a thermobalance. The amount of oxidation of coated samples decreased by half compared with that of uncoated samples, indicating that the coating was effective in inhibiting oxidation. However, the hydrogen absorption of coated samples was found to be higher than that of uncoated samples. In this paper, we discuss the mechanism behind this difference in hydrogen absorption and its effect on mechanical properties.
Hirota, Noriaki; Funamoto, Kodai*; Tachibana, Yukio
Zairyo, 72(3), p.255 - 261, 2023/03
For the purpose of developing metallic materials with excellent corrosion resistance under boiling sulfuric acid environment, the coated materials were evaluated for their corrosion resistance and the differences in surface morphology were investigated. As a result, the corrosion resistance of SUS304 coated and sintered eight times by chemical densified coating method (S-ZAC) was maintained at the point after 12h corrosion test, but the corrosion rate rapidly increased after 100h corrosion test. The cross-sectional microstructural analysis of the specimens showed that only a small amount of SiO
remained on the surface, while CrO
completely disappeared. The mechanism of film delamination in S-ZAC is assumed to be due to the thermal expansion caused by heating, which resulted in curvature of the thick film and cracks at the CrO and SiO interfaces. On the other hand, SUS304 coated with higher density of CrO by repeating the coating and sintering eleven times (MS-ZAC) showed excellent corrosion resistance as well as SiC even after 100h corrosion test. The results of cross-sectional microstructuCrO particle layer, in addition to the thinning of the entire film.
Kawai, Keito*; Nemoto, Yoshiyuki; Yamashita, Shinichiro; Ishijima, Yasuhiro; Ioka, Ikuo; Funamoto, Kodai*; Atsumi, Hisao*
no journal, ,
no abstracts in English
Kawai, Keito*; Fujimura, Yuki; Kondo, Keietsu; Abe, Yosuke; Ishikawa, Norito; Nemoto, Yoshiyuki; Yamashita, Shinichiro; Ishijima, Yasuhiro; Ioka, Ikuo; Funamoto, Kodai*; et al.
no journal, ,
In the previous report, we reported on the differences in oxidation and hydrogen absorption behavior of Zircaloy-4 cladding specimen and specimen with chromium (Cr) coating on its outer surfaces when they were subjected to oxidation tests in high temperature steam at 1100
C for 20 minutes. In this report, we describe the details of the cross-sectional observation of these specimens and the results of the evaluation of the differences in the shape and distribution of hydrides and other substances depending on the presence or absence of Cr coating.
Kawai, Keito*; Nemoto, Yoshiyuki; Fujimura, Yuki; Kondo, Keietsu; Abe, Yosuke; Mohamad, A. B.; Pham, V. H.; Ishikawa, Norito; Ishijima, Yasuhiro; Ioka, Ikuo; et al.
no journal, ,
no abstracts in English
