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Terunuma, Akihiro; Mimura, Ryuji; Nagashima, Hisao; Aoyagi, Yoshitaka; Hirokawa, Katsunori*; Uta, Masato; Ishimori, Yuu; Kuwabara, Jun; Okamoto, Hisato; Kimura, Yasuhisa; et al.
JAEA-Review 2016-008, 98 Pages, 2016/07
JAEA-Review-2016-008.pdf:11.73MB
Japan Atomic Energy Agency formulated the plan to achieve the medium-term target in the period of April 2010 to March 2015(hereinafter referred to as "the second medium-term plan"). JAEA determined the plan for the business operations of each year (hereinafter referred to as "the year plan"). This report is that the Sector of Decommissioning and Radioactive Waste Management has summarized the results of the decommissioning technology development and decommissioning of nuclear facilities which were carried out in the second medium-term plan.
Nagashima, Nobuo*; Hayakawa, Masao*; Tsukada, Takashi; Kaji, Yoshiyuki; Miwa, Yukio*; Ando, Masami*; Nakata, Kiyotomo*
Atsuryoku Gijutsu, 47(4), p.236 - 244, 2009/07
In this study, micro-hardness tests and AFM observations were performed on SUS316L low-carbon austenitic stainless steel pre-strained by cold rolling to investigate its deformation behavior. The following results were obtained. Despite the fact that the same plastic strain was applied, post-tensile test AFM showed narrower slip-band spacing in a reduction in area of 30% cold-rolled specimen than the unrolled specimen. Concentrated slip bands were observed near grain boundaries. Micro-hardness exceeding 300 was found to occur frequently in after tensile test specimens with a reduction in area of 30% or more, particularly at grain boundaries. It is suggested that the nonuniformity of deformation at grain boundaries plays an important role of IGSCC crack propagation mechanism of low-carbon austenitic stainless steel.
Kaji, Yoshiyuki; Miwa, Yukio; Tsukada, Takashi; Hayakawa, Masao*; Nagashima, Nobuo*
JAEA-Research 2008-064, 118 Pages, 2008/08
JAEA-Research-2008-064.pdf:26.9MB
This report describes a result of the research conducted by the Japan Atomic Energy Agency and the National Institute for Materials Science under contract with JNES that was concerned with a multi-scale analysis of plastic deformation behavior at the crack tip of SCC. In this research, analyses of the plastic deformation behavior and microstructure around the crack tip were performed in a nano-order scale. The hardness measured in nano, meso and macro scales was employed as a common index of the strength, and the essential data necessary to understand the SCC propagation behavior were acquired and analyzed that are mainly a size of plastic deformation region and a microstructural information in the region, e.g. data of crystallografy, microscopic deformation and dislocations at the inside of grains and grain boundaries.
Kaji, Yoshiyuki; Miwa, Yukio; Tsukada, Takashi; Hayakawa, Masao*; Nagashima, Nobuo*
JAEA-Research 2007-008, 69 Pages, 2007/03
JAEA-Research-2007-008.pdf:25.87MB
The research was carried out to evaluate the validity of the SCC growth data acquired in the IGSCC project based on a mechanistic understanding of SCC. The hardness measured in nano, meso and macro scales was employed as a common index of the strength, and the essential data necessary to understand the SCC propagation behavior were acquired and analyzed that are mainly a size of plastic deformation region and a microstructural information in the region, e.g. data of crystallografy, microscopic deformation and dislocations at the inside of grains and grain boundaries. In this year, we analyzed the state of plastic deformation region at the crack tip of IGSCC under various conditions and investigated relationship between crack growth behavior and stress intensity factor. Especially, we investigated in detail about two different hardened specimens used in the SCC growth tests in the IGSCC project.
Nagashima, Nobuo*; Hayakawa, Masao*; Tsukada, Takashi; Kaji, Yoshiyuki; Miwa, Yukio; Ando, Masami*; Nakata, Kiyotomo*
Proceedings of 13th International Conference on Environmental Degradation of Materials in Nuclear Power Systems (CD-ROM), 15 Pages, 2007/00
Stress corrosion cracking (SCC) was found in shroud and PLR piping made of low-carbon austenitic stainless steels in Japanese BWR plants. The intergranular type (IG) SCC propagated in hardened heat affected zones (HAZ) around welds. Strength behavior and local plastic deformation for a low-carbon austenitic stainless steel 316L, cold-rolled at the reductions in area of 10, 30% at room temperature to simulate the hardened HAZ, were measured by a micro-hardness test machine and observed by atomic force microscopy (AFM), respectively. The tensile deformation at yield point (0.2% plastic strain) had given to the work-hardened 316L to simulate the plastic zone at the crack tip. It is suggested that one of the IGSCC propagation mechanisms for 316L was related with the intergranular strength behavior and local plastic deformation around grain boundaries.
Kaji, Yoshiyuki; Miwa, Yukio; Tsukada, Takashi; Hayakawa, Masao*; Nagashima, Nobuo*; Matsuoka, Saburo*
JAERI-Research 2005-029, 156 Pages, 2005/09
JAERI-Research-2005-029.pdf:57.24MB
This report describes a result of the research conducted under contract with JNES that was concerned with a multi-scale analysis of plastic deformation behavior at the crack tip of SCC. The research was carried out to evaluate the validity of the SCC growth data acquired in the IGSCC project based on a mechanistic understanding of SCC. For the purpose, in this research, analyses of the plastic deformation behavior and microstructure around the crack tip were performed in a nano-order scale. The hardness measured in nano, meso and macro scales was employed as a common index of the strength, and the essential data necessary to understand the SCC propagation behavior were acquired and analyzed that are mainly a size of plastic deformation region and a microstructural information in the region, e.g. data of crystallografy, microscopic deformation and dislocations at the inside of grains and grain boundaries.
Miura, Yukitoshi; *; *; Hoshino, Katsumichi; *; *; Kasai, Satoshi; Kawakami, Tomohide; Kawashima, Hisato; Maeda, M.*; et al.
Fusion Energy 1996, p.167 - 175, 1997/05
no abstracts in English
*; *; *; *; *; *; *; Oikawa, Toshihiro; *; *; et al.
Fusion Energy 1996, p.885 - 890, 1997/05
no abstracts in English
Kubo, Hirotaka; Sugie, Tatsuo; *; Sakasai, Akira; Koide, Yoshihiko; Akaoka, Nobuo*; Nishitani, Takeo; Itami, Kiyoshi; Kawano, Yasunori; Nagashima, Keisuke; et al.
IAEA-TECDOC-536, p.139 - 144, 1990/00
no abstracts in English
Kubo, Hirotaka; Sugie, Tatsuo; Sakasai, Akira; Koide, Yoshihiko; *; Hirayama, Toshio; Nishitani, Takeo; Nagashima, Keisuke; Akaoka, Nobuo*; Takeuchi, Hiroshi; et al.
Nuclear Fusion, 29(4), p.571 - 582, 1989/04
Times Cited Count：9 Percentile：41.38(Physics, Fluids & Plasmas)no abstracts in English
Koide, Yoshihiko; Hirayama, Toshio; Sugie, Tatsuo; Sakasai, Akira; Kubo, Hirotaka; Akaoka, Nobuo*; Nishitani, Takeo; Nagashima, Keisuke; Shirai, Hiroshi; Takeuchi, Hiroshi; et al.
Nuclear Fusion, 28(10), p.1835 - 1844, 1988/10
Times Cited Count：5 Percentile：26.43(Physics, Fluids & Plasmas)no abstracts in English
Kaji, Yoshiyuki; Miwa, Yukio; Tsukada, Takashi; Nagashima, Nobuo*; Hayakawa, Masao*; Ando, Masami*; Nakata, Kiyotomo*; Koshiishi, Masato*
no journal, ,
In recent years, incidents of the stress corrosion cracking (SCC) were frequently reported that occurred in the weld part of core shroud and primary loop recirculation (PLR) piping of low carbon stainless steels, and the cause investigation and measure become the present important issue. In this study, to investigate the effect of plastic deformation behavior at the crack, analyses of plastic deformation behavior at the SCC crack tip were performed by electron back-scattering diffraction pattern (EBSP) method. SCC crack propagated along the grain boundary in the 45 degree direction of a fatigue crack, especially random grain boundary. The plastic deformation showed 10 to 20% in the one grain region of the crack. The plastic deformation behavior was different in both of a SCC crack and large plastic deformation was observed on one side of grain. From these results, it was considered that SCC crack propagation behavior was controlled by plastic deformation of very near crack tip.
