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Yamaguchi, Yoshihito; Katsuyama, Jinya; Li, Y.; Onizawa, Kunio
Journal of Pressure Vessel Technology, 142(2), p.021906_1 - 021906_11, 2020/04
Times Cited Count：1 Percentile：7.79(Engineering, Mechanical)Kasahara, Shigeki; Chimi, Yasuhiro; Hata, Kuniki; Fukuya, Koji*; Fujii, Katsuhiko*
Proceedings of 19th International Conference on Environmental Degradation of Materials in Nuclear Power Systems - Water Reactors (Internet), p.1345 - 1355, 2019/08
This paper describes empirical equation development of crack growth rates (CGR) in consideration of IASCC of neutron irradiated stainless steel to contribute to structural integrity assessment of BWR reactor internals. Empirical equations of CGR (da/dt) were developed based on a formula of da/dt = M
K
, assuming that "M" and "n" tend to be saturated with increasing neutron fluence. To obtain the empirical equations for normal water chemistry (NWC) and hydrogen water chemistry (HWC) of BWR, a data fitting with least square method was applied to the datasets consisting of F, K and CGR from post irradiation examinations of neutron irradiated stainless steel under simulated NWC and HWC conditions from open literature. As a result, calculated results by the equation for NWC showed good agreement with measured CGR data, meanwhile those for HWC did not. The above difference was seemed to be attributed that CGR data obtained under HWC conditions were scattered extensively.
Yamaguchi, Yoshihito; Katsuyama, Jinya; Li, Y.
Proceedings of 2018 ASME Pressure Vessels and Piping Conference (PVP 2018), 8 Pages, 2018/07
In order to assess the structure integrity of cracked pipes considering occurrence of large earthquakes, crack growth evaluation method for cracked pipes is important. In present study, evaluation method of crack growth by seismic loading was proposed for a dissimilar metal weld joint of nickel based alloy through experimental study using small specimens. Then, validation of the proposed method was performed through crack growth tests by using dissimilar metal weld pipe with circumferential through-wall crack. The predicted crack growth values were in good agreement with the experimental results and the applicability of the proposed method was confirmed.
Hasegawa, Kunio*; Mare
, V.*; Yamaguchi, Yoshihito
Journal of Pressure Vessel Technology, 139(3), p.034501_1 - 034501_5, 2017/06
Times Cited Count：2 Percentile：12.73(Engineering, Mechanical)Nagai, Masaki*; Lu, K.; Kamaya, Masayuki*
Nihon Kikai Gakkai M&M 2016 Zairyo Rikigaku Kanfuarensu Koen Rombunshu (Internet), p.481 - 483, 2016/10
In nuclear power plants, a number of cracks attributed to stress corrosion cracking (SCC) have been detected in welds made with nickel alloy weld metals. One of the characteristics of these cracks is that crack aspect ratio 
is greater than 0.5, where a is the crack depth and 
is the crack length. When a crack is detected in components of nuclear power plants during in-service inspection, flaw evaluation is conducted according to the requirement of codes such as JSME Rules on Fitness-for-Service for Nuclear Power Plants. Here, the stress intensity factor plays an important role for predicting crack growth behavior due to fatigue and/or SCC. Although several solutions of the stress intensity factor are already given in the JSME code, no solutions are available for the cracks with 
0.5. According to the current code, surface cracks with 0.5 are characterized as semi-circular shape 
. To evaluate these cracks in a rational manner, several solutions have been proposed for cracks with 0.5. In this paper, comprehensive comparison was made between solutions for cracks 0.5, and benchmark analysis on SCC crack growth was performed.
Hasegawa, Kunio; Li, Y.; Saito, Koichi*
Journal of Pressure Vessel Technology, 137(4), p.041101_1 - 041101_7, 2015/08
Times Cited Count：3 Percentile：16.3(Engineering, Mechanical)If a subsurface flaw is located near a component surface, the subsurface flaw is transformed to a surface flaw in accordance with a flaw-to-surface proximity rule. The re-characterization process from subsurface to surface flaw is adopted in all fitness-for-service (FFS) codes. However, the concrete criteria of the re-characterizations are different among the FFS codes. Cyclic tensile experiment was conducted on a carbon steel flat plate with a subsurface flaw at ambient temperature. The objective of the paper is to compare the experiment and calculation of fatigue crack growth behavior for a subsurface flaw and the transformed surface flaw, and to describe the validity of the flaw-to-surface proximity rule defined by ASME Code Section XI, JSME S NA1 Code and other codes.
Shibata, Katsuyuki; Kato, Daisuke*; Li, Y.*
Nihon Genshiryoku Gakkai-Shi, 43(4), p.387 - 396, 2001/04
Times Cited Count：2 Percentile：19.6(Nuclear Science & Technology)no abstracts in English
Inoue, Kazuko*; Horikawa, Takeshi*; *; *; Minakawa, Nobuaki; Tsuchiya, Yoshinori*; Morii, Yukio; *
Japanese Journal of Applied Physics, Part 1, 37(10), p.5680 - 5686, 1998/10
Times Cited Count：2 Percentile：13.52(Physics, Applied)no abstracts in English
Hayashi, Makoto*; Okido, Shinobu*; Minakawa, Nobuaki; Morii, Yukio
Zairyo, 47(4), p.420 - 426, 1998/04
no abstracts in English
Kasahara, Shigeki; Fukuya, Koji*; Chimi, Yasuhiro; Fujii, Katsuhiko*; Koshiishi, Masato*
no journal, ,
no abstracts in English
Kasahara, Shigeki; Fukuya, Koji*; Chimi, Yasuhiro; Fujii, Katsuhiko*; Koshiishi, Masato*
no journal, ,
no abstracts in English
Kasahara, Shigeki; Fukuya, Koji*; Chimi, Yasuhiro; Fujii, Katsuhiko*; Hata, Kuniki
no journal, ,
Disposition curves of crack growth rates (CGR) of stainless steel in appropriate consideration of IASCC are necessary for structural integrity assessment of reactor internals of BWRs. This paper describes empirical equations development of CGR (da/dt), as functions of stress intensity factors (K) and neutron dose (F) to contribute to improvement of the structural integrity assessment. Development started from a formula of da/dt=MK, and on the assumption that "M" and "n" tend to be saturated with increasing F. Datasets for fitting were prepared consisting of CGR, F and K from the results of PIE under simulated NWC conditions. Data fitting with least square method was applied to the datasets to obtain the equation. The results from the empirical equation were compared with the measured crack growth data, and validity of the equations were discussed from the viewpoints of statistical analysis.
Kasahara, Shigeki; Hata, Kuniki; Hanawa, Satoshi
no journal, ,
no abstracts in English
