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Okuda, Takahiro; Takahashi, Hideki*; Watakabe, Tomoyoshi
Mechanical Engineering Journal (Internet), 10(4), p.23-00075_1 - 23-00075_9, 2023/08
In recent years, to make the seismic design more rational for the piping systems in nuclear power plants, it has been expected to develop a design method considering plastic deformation and the accompanying energy dissipation of the piping itself. In this study, an extensive series of seismic response analyses was conducted to investigate the degree of influence of the plastic deformation of the pipe support structures on the seismic response of the entire piping system. The analyses include; plasticity is considered for (1) none, (2) the piping only, (3) the support structure only, and (4) both the piping and the support structure.
Kasahara, Shigeki; Chimi, Yasuhiro; Hata, Kuniki; Hanawa, Satoshi
Zairyo To Kankyo, 68(9), p.240 - 247, 2019/09
In order to study environment assisted cracking mechanism of stainless steel under BWR primary coolant condition, effects of applied load on oxidation in the vicinity of crack tips of CT specimens were evaluated. Loaded CT specimens were immersed in an aqueous condition at 290
C as a simulated BWR coolant condition, and microstructural observation on oxide near the tips of pre-cracks was carried out. Oxide inner layers, which consisted of fine grain magnetite containing Fe and Cr were formed, and oxide outer layers consisting of large grains of Fe
O
were observed to cover the inner layers. FEM analysis of stress and strain in the loaded CT specimen suggests that both of dislocations due to localized plastic deformation and elastic strain could play important roles to accelerate inner oxide formation in the vicinity of the crack tip of the specimens.
Kaji, Yoshiyuki; Miwa, Yukio; Tsukada, Takashi
Nihon Kikai Gakkai M&M 2005 Zairyo Rikigaku Kanfarensu Koen Rombunshu, p.175 - 176, 2005/12
From results of analysis of plastic deformation behavior at SCC crack tip by EBSP method, the conclusions was obtained as follows: (1)Regarding to basic data for quantitative evaluation of plastic deformation behavior at SCC crack tip, we obtained relationship between plastic deformation and misorientation of grain using SSRT result for SUS316L stainless steel in high temperature water and local plastic strain was able to estimate using this relationship. (2)From experimental results of plastic strain at SCC crack and ductile crack tips using relationship between misorientation and plastic deformation, plastic strain near ductile crack tip was larger than that at SCC crack tip. Plastic deformation region was, however, corresponded to region of about one grain at crack tip for both SCC and ductile cracks.
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.
Miwa, Yukio; Tsukada, Takashi; Jitsukawa, Shiro
Proceedings of 12th International Conference on Environmental Degradation of Materials in Nuclear Power Systems-Water Reactors (CD-ROM), p.311 - 318, 2005/00
Plastic deformation behavior to influence the stress corrosion cracking was studied for the thermally-sensitized and the irradiated type 316LN stainless steel. SSRT was conducted at 573 K in oxygenated water (DO=10ppm) for specimens. Each of the specimens was thermally sensitized at 1033 K for 100 h or irradiated at 473 K to 1 dpa. Between these specimens, the plastic deformation behavior and the IGSCC were compared. For the irradiated specimens, plastic deformation behavior such as the work hardening capability and the maximum stress where IASCC initiated was similar to that of thermally-sensitized specimens in true stress-true strain relation. Moreover, the effect of strain rate on %IGSCC was the same each other. It was suggested from these results that for specimens irradiated around 1 dpa, the initiation mechanism of IASCC was similar to that of IGSCC for thermally-sensitized specimens.
phaseSawai, Tomotsugu; Tabuchi, Masayuki*; Wakai, Eiichi; Hishinuma, Akimichi
Proceedings of Materials Research Society Symposium, Vol.650, p.R3.9.1 - R3.9.6, 2001/00
no abstracts in English
; Aoto, Kazumi; ;
JNC TN9400 2000-022, 46 Pages, 2000/03
ln this report, a study on the behaviors of the magnetization induced by mechanical damages is carried out. By introducing mechanical damages to a test-piece with a tension or/and a zero, tension fatigue testing and measuring the corresponding leakage flux signal, natural magnetization change is proved and found increasing with the mechanical damages (viz. plastic deformation or fatigue damages) though a saturation occurs when damage gets too large. From the experimental results of fatigue testing utilizing test-pieces with a central slit, it was verified that observing the natural leakage flux density (leakage flux without applying external magnetic field) is a reasonable way to identify fatigue cracks. A feature parameter (area of the 
B hysteresis curve) of the in-situ magnetic field signal measured during the fatigue testing is proposed for predicting the fatigue damages, which is found depending on the cyclic number of the applied loading. At last, residual magnetic fields of a magnetized test-piece are also measured and found depending on the applied plastic deformation in case that the plastic strain is not too small. From these experimental results, it is found that the approach detecting natural magnetization is applicable for monitoring the damage status though it may be not efficient for a scanning inspection concerning its small signal magnitude. On the other hand, the method employing permanent magnet is robust against the environment noise but possibly not valid for the ISl of a structural component with a relative low damage level. For practical application, efforts to evaluate the feasibility of the proposed method are necessary for more testing conditions especially its suitability in a practical environment.
Hayashi, Makoto*; Okido, Shinobu*; Minakawa, Nobuaki; Morii, Yukio
Zairyo, 47(4), p.420 - 426, 1998/04
no abstracts in English
SiUgajin, Mitsuhiro; Akabori, Mitsuo; Ito, Akinori; Ooka, Norikazu;
Journal of Nuclear Materials, 248, p.204 - 208, 1997/00
Times Cited Count：8 Percentile：56.36(Materials Science, Multidisciplinary)no abstracts in English
; ; Sato, Toshinori; Yoshioka, Naoya
PNC TN7410 92-046, 56 Pages, 1992/12
As a result of underground excavation to construct an underground facility, an excavation disturbed zone (EDZ) is often generated in rock mass around a shaft and a drift. In order to design and construct an underground facility, and to evaluate its long-term stability, it is necessary to understand the phenomena related to excavation disturbance. PNC (Power Reacter and Nuclear Fuel Development Corporation) excavated a shaft of 6m diameter and 152.3m depth in Neogene sedimentary rocks, and studied the influence induced by the shaft excavation on rock mass and groundwater flow around the shaft. This project was named SEE (Shaft Excavation Effects) project, and was carried out from 1978 to 1991. This report described a part of the SEE Project, focusing on mechanical and hydrological variation of rock mass around the shaft. The current conclusions were su㎜arized as follows: (1)Mechanical and hydrological variation of rock mass around the shaft was induced by stress redistribution and fracturing around the shaft. (2)The zone where mechanical and hydrological characteristics were varied was extended about 1m from shaft wall. (3)It is considered that unrecoverable deformation is generated in rock mass around a shaft because of fracturing and plastic deformation. We introduced a concept of permanent deformation modulus to take account of the unrecoverable deformation, and estimated the results of borehole jack tests. Consequently, we found the permanent deformation modulus was useful to identify the EDZ.
Ioka, Ikuo; *; Konishi, Takashi*
Zairyo, 38(434), p.1247 - 1253, 1989/11
no abstracts in English
; *; Minato, Akio; Tone, Tatsuzo
Nucl.Eng.Des./Fusion, 5, p.221 - 231, 1987/00
no abstracts in English
; *; ; *; *; *;
Journal of Nuclear Materials, 141-143, p.353 - 356, 1986/00
Times Cited Count：12 Percentile：77.31(Materials Science, Multidisciplinary)no abstracts in English
;
Journal of Nuclear Materials, 118, p.214 - 219, 1983/00
Times Cited Count：3 Percentile：44.36(Materials Science, Multidisciplinary)no abstracts in English
Xu, P. G.; Ishijima, Yasuhiro; Qiu, H.*
no journal, ,
Okuda, Takahiro; Takahashi, Hideki*; Morishita, Masaki
no journal, ,
This study describes the results of a series of seismic analyses conducted to clarify how plastic deformation of a pipe and its support structures affects the seismic response of the entire piping system. The analyses conducted include; plasticity is considered for (1)the support structure only, (2)the piping only and (3)both the piping and the support structure.
Okuda, Takahiro; Takahashi, Hideki*; Morishita, Masaki
no journal, ,
This paper describes the results of a series of seismic analyses conducted to clarify how plastic deformation of a pipe and its support structures affect the seismic response of the entire piping system. The first analyses include; plasticity is considered for (1) none, (2) the piping only, (3) the support structure only and (4) both the piping and the support structure. The second analyses are parametric survey of yield load and post yield stiffness of the restoring force characteristics of support structures.
Okuda, Takahiro; Watakabe, Tomoyoshi; Morishita, Masaki; Abe, Kenji*
no journal, ,
This paper describes the results of a series of seismic analyses to clarify how the plastic deformation of some support structures affects the seismic response of the entire piping system. The results of these analyses have revealed important implications for the seismic design of piping systems by elastic-plastic response analysis. First, regarding the order of the support structure considering plasticity, it is more effective to give priority to the plastic characteristics of the support structure showing a large load in the linear response analysis. Second, partially considering plasticity is more effective in reducing the burden of the entire design work than considering the plasticity of the entire support structure.
Shobu, Takahisa
no journal, ,
no abstracts in English
