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Journal Articles

Influence of Zn injection on PWSCC crack growth rates and oxide film properties of Alloy 600

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$$^{circ}$$C with a low-concentration (5-10 ppb) Zn injection under dissolved hydrogen (DH) conditions of 5, 30, and 50 cc/kgH$$_{2}$$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.

Journal Articles

Evaluation of crack growth rates and microstructures near the crack tip of neutron-irradiated austenitic stainless steels in simulated BWR environment

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:0 Percentile:0.01

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 $$sim$$288$$^{circ}$$C on neutron-irradiated 316L stainless steels (SSs) at $$sim$$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 $$<$$$$sim$$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.

Journal Articles

Bayesian nonparametric analysis of crack growth rates in irradiated austenitic stainless steels in simulated BWR environments

Chimi, Yasuhiro; Takamizawa, Hisashi; Kasahara, Shigeki*; Iwata, Keiko; Nishiyama, Yutaka

Nuclear Engineering and Design, 307, p.411 - 417, 2016/10

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

To investigate influential parameters for irradiation-assisted stress corrosion cracking (IASCC) growth behavior, we attempt to analyze statistically existing data on the crack growth rate (CGR) in irradiated austenitic stainless steels (SSs) in boiling water reactor (BWR) environments using the Bayesian nonparametric (BNP) method. From the probability distribution of CGR and some input parameters, such as yield stress of irradiated material ($$sigma$$$$_{rm YS-irr}$$), stress intensity factor (${it K}$), electrochemical corrosion potential (ECP), and fast neutron fluence, the mean CGR is estimated and compared with the measured CGR. The analytical results show good reproducibility of the measured CGR. The results also indicate the possible neutron fluence effects on CGR in high CGR region (i.e., high neutron fluence condition) by radiation-induced segregation (RIS), localized deformation, and/or other mechanisms than radiation hardening.

Journal Articles

The crack initiation and growth behavior for high temperature creep-fatigue interaction in notched specimen of Ni-based alloy

; *; ;

Nihon Kikai Gakkai Rombunshu, A, 52(477), p.1228 - 1231, 1986/00

no abstracts in English

Journal Articles

Effect of microstructure and strength of low alloy steels on cyclic crack growth in high temperature water

*; Nakajima, Hajime; ; ; Kondo, Tatsuo

Corrosion Fatigue; Mechanics, Metallurgy, Electrochemistry and Engineering, p.256 - 286, 1983/00

no abstracts in English

JAEA Reports

Cyclic Crack Growth Typical Weld HAZ Microstructures of SA 533gr.B Steel in Simulated BWR Environment

; ; Shindo, Masami; ; ; ; ; ; *; *; et al.

JAERI-M 82-062, 23 Pages, 1982/06

JAERI-M-82-062.pdf:1.31MB

no abstracts in English

Journal Articles

Role of mechanical factors in environmentally enhanced crack growth under cyclic loading

*; Nakajima, Hajime; Kondo, Tatsuo; *

Zairyo, 31(346), p.703 - 709, 1982/00

no abstracts in English

JAEA Reports

Creep Test of Type 304 Stainless Steel Cylindrical Tube Subjected to Internal Pressure

Ueda, Shuzo; ;

JAERI-M 9647, 22 Pages, 1981/08

JAERI-M-9647.pdf:0.77MB

no abstracts in English

Oral presentation

Effects of environmental mitigation and water radiolysis on crack growth in simulated BWR environment in highly irradiated 316L stainless steel

Chimi, Yasuhiro; Kasahara, Shigeki; Hata, Kuniki; Nishiyama, Yutaka; Seto, Hitoshi*; Chatani, Kazuhiro*; Kitsunai, Yuji*; Koshiishi, Masato*

no journal, , 

In order to investigate effects of environmental mitigation and water radiolysis caused by $$gamma$$-rays from radioactive material on irradiation-assisted stress corrosion cracking (IASCC) growth behavior for highly irradiated material, crack growth tests in simulated BWR water conditions (at 563 K) are performed. The specimens made of 316L stainless steels are irradiated with neutrons up to $$sim$$12 dpa in the Japan Materials Testing Reactor (JMTR). One of the specimens is annealed at 973 K for 1 hour to show almost recovered mechanical and micro-chemical properties corresponding to the unirradiated material. For low electrochemical corrosion potential (ECP) condition, the crack growth rate (CGR) is suppressed by about one order of magnitude in high stress intensity factor (K) condition. This result indicates that environmental mitigation for crack growth can be found even under severe conditions on material and stress factors. The effects of water radiolysis on the CGRs are discussed.

Oral presentation

Evaluation of crack growth rates and microstructures near crack tip of neutron-irradiated 316L stainless steels in simulated BWR environment

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 $$sim$$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.

Oral presentation

Relationship between crack growth rates and locally deformed structures in irradiated 316L stainless steels

Chimi, Yasuhiro; Kasahara, Shigeki; Nishiyama, Yutaka; Seto, Hitoshi*; Kitsunai, Yuji*; Koshiishi, Masato*

no journal, , 

In order to understand irradiation-assisted stress corrosion cracking (IASCC) growth behavior, crack growth tests using compact tension (CT) specimens made of neutron-irradiated 316L stainless steels (SSs) were performed in simulated BWR environments (at $$sim$$288$$^{circ}$$C). Moreover, microstructures of deformed areas were observed by transmission electron microscope (TEM) after straining tensile specimens made of neutron-irradiated 316L SSs. As a result, for lower neutron dose than $$<sim$$1.9 dpa, the crack growth rates (CGRs) show effective environmental mitigation and the deformed structures show tangling of dislocations. On the other hand, for higher neutron dose than $$>sim$$2.7 dpa, the CGRs show small environmental mitigation and the deformed structures consist mainly of dislocation channels. From the relationship between CGRs and deformed structures, mechanisms on IASCC growth will be discussed.

Oral presentation

Influence of Zn injection on PWSCC crack growth rates of alloy 600 under simulated primary coolant environments of pressurized water reactor

Chimi, Yasuhiro; Sato, Kenji*; Kasahara, Shigeki; Umehara, Ryuji*; Hata, Kuniki; Hanawa, Satoshi; Nishiyama, Yutaka

no journal, , 

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 in simulated primary water environment of pressurized water reactor (PWR) at 320$$^{circ}$$C and 360$$^{circ}$$C, with and without Zn injection, under dissolved hydrogen (DH) conditions of 5, 30, and 50 cc/kgH$$_{2}$$O. As a result of the crack growth tests at 360$$^{circ}$$C, it is implied that Zn injection suppresses the oxidation inside the crack and the crack growth rate (CGR). From the crack growth tests at 320$$^{circ}$$C with Zn injection, DH-dependence of CGR showed a similar tendency to the predicted CGR based on the CGR data without Zn injection. Obvious influence of Zn injection on DH-dependence of CGR at 320$$^{circ}$$C was not observed in the present study.

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