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Hirota, Noriaki; Nakano, Hiroko; Fujita, Yoshitaka; Takeuchi, Tomoaki; Tsuchiya, Kunihiko; Demura, Masahiko*; Kobayashi, Yoshinao*
The IV International Scientific Forum "Nuclear Science and Technologies"; AIP Conference Proceedings 3020, p.030007_1 - 030007_6, 2024/01
Dynamic strain aging (DSA) and intergranular stress corrosion cracking (intragranular SCC) occur in high temperature pressurized water simulating a boiling water reactor environment due to changes in dissolved oxygen (DO) content, respectively. In order to clearly understand the difference between these phenomena, the mechanism of their occurrence was summarized. As a result, it was found that DSA due to intragranular cracking occurred in SUS304 stainless steel at low DO 
1 ppb, while DSA was suppressed at DO 100 to 8500 ppb due to the formation of oxide films on the surface. On the other hand, when DO was increased to 20000 ppb, the film was peeled from the matrix, O element diffused to the grain boundary of the matrix, resulting in intergranular SCC. These results are indicated that the optimum DO concentration must be adjusted to suppress crack initiation due to DSA and intergranular SCC.
Chimi, Yasuhiro; Sato, Kenji*; Kasahara, Shigeki; Umehara, Ryuji*; Hanawa, Satoshi
Proceedings of Contribution of Materials Investigations and Operating Experience to Light Water NPPs' Safety, Performance and Reliability (FONTEVRAUD-9) (Internet), 10 Pages, 2018/09
To investigate the influence of Zinc (Zn) injection on primary water stress corrosion cracking (PWSCC) growth behavior, crack growth tests of 10% cold-worked Alloy 600 were performed in simulated primary water environment of pressurized water reactor (PWR) at 320
C with a low-concentration (5-10 ppb) Zn injection under dissolved hydrogen (DH) conditions of 5, 30, and 50 cc/kgH
O. As a result of the crack growth tests, DH-dependence of crack growth rate (CGR) showed a similar tendency to the predicted CGR based on the CGR data without Zn injection, indicating almost no effect of a low-concentration Zn injection on the crack growth behavior. Moreover, the microstructural analyses of oxide films formed inside the crack and on the specimen surface were conducted, and the intake of Zn in the oxides was detected on the specimen surface, but not detected inside the crack. This result was considered to be the cause of no Zn injection effect on the crack growth behavior.
Chimi, Yasuhiro; Kasahara, Shigeki; Seto, Hitoshi*; Kitsunai, Yuji*; Koshiishi, Masato*; Nishiyama, Yutaka
Proceedings of the 18th International Conference on Environmental Degradation of Materials in Nuclear Power Systems - Water Reactors, Vol.2, p.1039 - 1054, 2018/00
Times Cited Count：2 Percentile：54.91(Materials Science, Multidisciplinary)In order to understand irradiation-assisted stress corrosion cracking (IASCC) growth behavior, crack growth rate (CGR) tests have been performed in simulated Boiling Water Reactor water conditions at 
288C on neutron-irradiated 316L stainless steels (SSs) at 12-14 dpa. After the tests, the microstructures near the crack tip of the specimens are examined with scanning transmission electron microscope (FE-STEM). In comparison with a previous study at 2 dpa, this result shows a less benefit of low electrochemical corrosion potential (ECP) conditions on CGR. A crack tip immersed over 1000 hours was filled with oxides, while almost no oxide film was observed near the crack front in the low-ECP conditions. In addition, a high density of deformation twins and dislocations were found near the fracture surface of the crack front. It is considered that both localized deformation and oxidation are possible dominant factors for the SCC growth in highly irradiated SSs.
Chimi, Yasuhiro; Kitsunai, Yuji*; Kasahara, Shigeki; Chatani, Kazuhiro*; Koshiishi, Masato*; Nishiyama, Yutaka
Journal of Nuclear Materials, 475, p.71 - 80, 2016/07
Times Cited Count：12 Percentile：72.01(Materials Science, Multidisciplinary)To elucidate the mechanism of irradiation-assisted stress corrosion cracking (IASCC) in high-temperature water for neutron-irradiated austenitic stainless steels (SSs), the locally deformed structures, the oxide films formed on the deformed areas, and their correlation were investigated. Tensile specimens made of irradiated 316L SSs were strained 0.1%-2% at room temperature or at 563 K, and the surface structures and crystal misorientation among grains were evaluated. The strained specimens were immersed in high-temperature water, and the microstructures of the oxide films on the locally deformed areas were observed. The appearance of visible step structures on the specimens' surface depended on the neutron dose and the applied strain. The surface oxides were observed to be prone to increase in thickness around grain boundaries (GBs) with increasing neutron dose and increasing local strain at the GBs. No penetrative oxidation was observed along GBs or along surface steps.
-ray irradiation on pitting corrosion of fuel cladding in water containing sea saltMotooka, Takafumi; Tsukada, Takashi
Proceedings of 2014 Nuclear Plant Chemistry Conference (NPC 2014) (USB Flash Drive), 9 Pages, 2014/10
In Fukushima Daiichi Nuclear Power Station (1F), seawater was injected into spent fuel pools in March 2011. Zircaloy-2 is adopted for the fuel cladding at 1F. Zirconium alloys including Zircaloy-2 are susceptible to pitting corrosion in oxidizing chloride solutions. In this study, we investigated the effect of oxide film formed during -ray irradiation on pitting corrosion of fuel cladding in water containing sea salt. The pitting potentials of Zircaloy-2 were measured using the water containing artificial sea salt. Changes in the composition of water containing sea salt were analyzed before and after -ray irradiation. The characteristics of the oxide films formed on Zircaloy-2 were evaluated by X-ray photoelectron spectroscopy. Solution analyses for water containing sea salt showed that hydrogen peroxide was generated by the irradiation. The pitting potential of Ziracloy-2 with oxide film formed under -ray irradiation was higher than that with oxide film formed without irradiation. X-ray photoelectron spectroscopy indicated that the oxide film was composed of zirconium oxide and the growth of oxide film was enhanced during the irradiation. It could thus be explained that the enhanced growth of oxide film under -ray irradiation caused the higher pitting potential.
Nemoto, Yoshiyuki; Miwa, Yukio; Kikuchi, Masahiko; Kaji, Yoshiyuki; Tsukada, Takashi; Tsuji, Hirokazu
Journal of Nuclear Science and Technology, 39(9), p.996 - 1001, 2002/09
Times Cited Count：6 Percentile：39.00(Nuclear Science & Technology)Surface morphology of oxidized stainless steel was evaluated using atomic force microscope (AFM) and scanning electron microscope (FE-SEM). Cross-sectional morphology of oxide layer on the specimens was evaluated using FE-SEM after fabrication. Focused ion beam (FIB) technique was applied to fabricate thin film samples of oxide films, which were used for microstructure observation by transmission electron microscope (FE-TEM), and microscopic chemical analysis by energy dispersed X-ray spectrometer (EDS). These preparations and observations were successful, and microstructure and chemical composition of oxide films were evaluated on nanometer scale. Effects of silicon (Si) doping and dissolved oxygen (DO) content in water for oxide layer formation are discussed.
Mishima, Kaichiro*; Saito, Yasushi*
JAERI-Tech 2002-014, 83 Pages, 2002/03
JAERI-Tech-2002-014.pdf:6.83MB
no abstracts in English
Nemoto, Yoshiyuki; Miwa, Yukio; Tsukada, Takashi; Kikuchi, Masahiko; Tsuji, Hirokazu
JAERI-Tech 2001-079, 25 Pages, 2001/12
JAERI-Tech-2001-079.pdf:6.76MB
Development and research about analytical method for the study of oxide film on austenitic stainless steel had been conducted from the point of view for basic study of IASCC (Irradiation Assisted Stress Corrosion Cracking). Nickel plating and copper plating had been compared as the oxide film protection while the fabrication for cross sectional observation. And thin film specimens for microstructural observation were fabricated using FIB (Focused Ion Beam) technique. Microstructure of oxide film on stainless steel had been observed with FE-TEM (Field Emission gun - Transmission Electron Microscope), and the chemical composition was analyzed with EDS (Energy dispersed X-ray Spectrometer). The oxide film had been formed in high pressure (8MPa) and high temperature (288
) water, contains saturated oxygen. The thickness of oxide film was about 1
m as maximum. Micro grains of Fe oxide with 100nm in diameter were formed in the oxide film. On the boundary with alloy, there was about 10nm thickness of passive film formed with Cr oxide.
Yamaki, Tetsuya; Asai, Keisuke*
Langmuir, 17(9), p.2564 - 2567, 2001/05
Times Cited Count：42 Percentile：92.04(Chemistry, Multidisciplinary)A new type of TiO nanosheet-organic complex multilayer film was successfully prepared by the Langmuir-Blodgett technique. Surface pressure-area curves demonstrated that a stable monolayer of dioctadecyldimethylammonium bromide (DODAB) was formed on an aqueous suspension of TiO nanosheets derived from an exfoliated layered titanate, H
Ti
□
O
・HO (x0.7; □, vacancy). The hybrid monolayer of the ammonium amphiphiles and the TiO nanosheet was quantitatively transferred onto a hydrophobic quartz plate to form a multilayer film. X-ray diffraction measurements confirmed the formation of an ordered structure of DODAB/TiO with an interlayer distance of 3.4 nm.
Kameo, Yutaka
Proceedings of OECD/NEA Workshop on Evaluation of Speciation Technology, p.241 - 245, 1999/00
no abstracts in English
Ioka, Ikuo; Onuki, Kaoru; Futakawa, Masatoshi; Kuriki, Yoshiro*; ; Nakajima, Hayato; Shimizu, Saburo
Zairyo, 46(9), p.1041 - 1045, 1997/09
no abstracts in English
; ; Murakami, Yoshio
JAERI-M 83-112, 21 Pages, 1983/07
no abstracts in English
;
JAERI-M 82-055, 51 Pages, 1982/06
no abstracts in English
Katsuta, Hiroji; R.B.McLellan*; Furukawa, Kazuo
Journal of Physics and Chemistry of Solids, 43(6), p.533 - 538, 1982/00
Times Cited Count：41 Percentile：88.46(Chemistry, Multidisciplinary)no abstracts in English
Katsuta, Hiroji; Furukawa, Kazuo
Journal of Nuclear Science and Technology, 18(2), p.143 - 151, 1981/00
Times Cited Count：46 Percentile：96.32(Nuclear Science & Technology)no abstracts in English
; ; ; ; ;
Anal. Chem., 52(11), p.1601 - 1606, 1980/00
Times Cited Count：18 Percentile：36.96(Chemistry, Analytical)no abstracts in English
; Kondo, Tatsuo
Proc.of 2nd Japan-US HTGR Safety Technology Seminar,Material Properties andDesign Method Session, 12 Pages, 1978/00
no abstracts in English
Yamamoto, Katsumune; ;
Nihon Genshiryoku Gakkai-Shi, 17(11), p.609 - 616, 1975/11
no abstracts in English
;
Electrochem.Technol., 4(3-4), p.93 - 99, 1966/00
no abstracts in English
Chimi, Yasuhiro; Kasahara, Shigeki*; Nishiyama, Yutaka; Seto, Hitoshi*; Chatani, Kazuhiro*; Kitsunai, Yuji*; Koshiishi, Masato*
no journal, ,
In order to understand irradiation-assisted stress corrosion cracking (IASCC) growth behavior, crack growth tests in simulated BWR water conditions (at 563 K) were performed using neutron-irradiated specimens made of 316L stainless steels, and the oxide film properties and locally deformed structures near the crack tip have been investigated by transmission electron microscopy (TEM). When electrochemical corrosion potential (ECP) of the materials was lowered by deaeration and hydrogen injection into feed water, apparent suppression of oxidation inside the cracks was observed as well as suppression of the crack growth rate (CGR). In the presentation, the TEM results of the locally deformed structures along the cracks are also reported, and the relation among the CGR, oxide film properties, and locally deformed structures is discussed.
