Stress corrosion cracking behavior of type 304 stainless steel irradiated under different neutron dose rates at JMTR

Kaji, Yoshiyuki; Kondo, Keietsu; Aoyagi, Yoshiteru; Kato, Yoshiaki; Taguchi, Taketoshi; Takada, Fumiki; Nakano, Junichi; Ugachi, Hirokazu; Tsukada, Takashi; Takakura, Kenichi*; et al.

Proceedings of 15th International Conference on Environmental Degradation of Materials in Nuclear Power Systems - Water Reactors (CD-ROM), p.1203 - 1216, 2011/08

In order to investigate the effect of neutron dose rate on tensile property and irradiation assisted stress corrosion cracking (IASCC) growth behavior, the crack growth rate (CGR) test, tensile test and microstructure observation have been conducted with type 304 stainless steel specimens. The specimens were irradiated in high temperature water simulating the temperature of boiling water reactor (BWR) up to about 1dpa with two different dose rates at the Japan Materials Testing Reactor (JMTR). The radiation hardening increased with the dose rate, but there was little effect on CGR. Increase of the yield strength of specimens irradiated with the low dose rate condition was caused by the increase of number density of frank loops. Little difference of radiation-induced segregation at grain boundaries was observed in specimens irradiated by different dose rates. Furthermore, there was little effect on local plastic deformation behavior near crack tip in the crystal plasticity simulation.

Equipment for microstructural observation of JMTR Hot Laboratory

Kato, Yoshiaki; Takada, Fumiki; Sozawa, Shizuo; Nakagawa, Tetsuya

JAEA-Testing 2009-008, 29 Pages, 2010/03

JAEA-Testing-2009-008.pdf:28.27MB

This report summarizes about the new equipment for the microstructural observation on the nuclear materials such as the structural material of light water reactor, which was installed in the JMTR Hot Laboratory. This experimental device, one of the PIE apparatuses, is useful to obtain the technical knowledge on the material degradation behavior by neutron irradiation damage and accumulate the data base for the integrity evaluation of nuclear power plant.

Installation of remote-handling typed EBSD-OIM analyzer for heavy irradiated reactor materials

Kato, Yoshiaki; Miwa, Yukio; Takada, Fumiki; Omi, Masao; Nakagawa, Tetsuya

JAEA-Testing 2008-005, 48 Pages, 2008/06

JAEA-Testing-2008-005.pdf:13.36MB

This report is concerned with the EBSD-OIM analyzer for irradiated reactor materials, which was installed in the JMTR Hot Laboratory. As the first time in the world, it was installed in a hot cell as one of the examination facilities for irradiated nuclear materials and contributes to studies on IASCC (irradiation aided stress corrosion cracking) and IGSCC (irradiation grain boundary stress corrosion cracking). Its maintenance and operating experiences were described.

Technology development on production of test specimens from irradiated capsule outer-tube and mechanical evaluation test of stainless steel with high dose carried out by the technology

Hayashi, Koji; Shibata, Akira; Iwamatsu, Shigemi; Sozawa, Shizuo; Takada, Fumiki; Omi, Masao; Nakagawa, Tetsuya

JAEA-Technology 2008-016, 51 Pages, 2008/03

JAEA-Technology-2008-016.pdf:45.58MB

The irradiation capsule 74M-52J was irradiated during total 136 cycles at reactor core of JMTR and the maximum neutron dose reached on 3.910n/m at the capsule outer-tube made of a type 304 stainless steel. In order to produce mechanical test specimens from the outer tube, a punching technique was developed as a simple remote-handling method in a hot-cell. From comparison between the punching and the mechanical cutting methods, it was clarified that the punching technique was applicable to practical use. Moreover, an evaluation test of mechanical properties using specimens sampled from the 74M-52 was performed in-water high temperature condition, less than 288C. The result shows that the residual elongation is 18% at 150C and 13% at 288C. It was confirmed that the type 304 stainless steel irradiated up to such high dose shows enough ductility.

Technology development on analysis program for measuring fracture toughness of irradiated specimens

Shibata, Akira; Takada, Fumiki

JAEA-Technology 2007-031, 24 Pages, 2007/03

JAEA-Technology-2007-031.pdf:3.69MB

The fracture toughness which represents resistance for brittle or ductile fracture is one of the most important material property concerning linear and non-linear fracture mechanics analyses. In order to respond to needs of collecting data relating to fracture toughness of pressure vessel and austenitic stainless steels, fracture toughness test for irradiated materials has been performed in JMTR Hot Laboratory. On the other hand, there has been no computer program for analysis of fracture toughness using the test data obtained from the test apparatus installed in the hot cell. Therefore, only load-displacement data have been provided to users to calculate fracture toughness of irradiated materials. Recently, request of analysis of fracture toughness have been increased. Thus a computer program, which calculates the amount of the crack extension, the compliance and the fracture toughness from the data acquired from the test apparatus installed in the hot cell, has been developed. In the program unloading elastic compliance method is applied based on ASTM E1820-01. Through the above development, the request for the fracture toughness analysis can be satisfied and the fracture toughness of irradiated test specimens can be provided to users.

Neutron irradiation effect on mechanical properties of SS/SS HIP joint materials for ITER shielding blankets

Yamada, Hirokazu*; Sato, Satoshi; Mori, Kensuke*; Nagao, Yoshiharu; Takada, Fumiki; Kawamura, Hiroshi

Fusion Engineering and Design, 81(1-7), p.631 - 637, 2006/02

https://doi.org/10.1016/j.fusengdes.2005.07.012

This study estimated the neutron irradiation effect with 1.5 dpa on the mechanical properties of the SS/SS HIP joint materials jointed in the standard HIP joint condition. Results of this study showed that the HIP process in the standard HIP condition could make SS/SS HIP joint material of which tensile properties was equivalent to that of the SS base material. In addition, the effect of surface roughness at the HIP joint material on the mechanical properties of SS/SS HIP joint material was estimated.

Radiation hardening and -embrittlement due to He production in F82H steel irradiated at 250 C in JMTR

Wakai, Eiichi; Jitsukawa, Shiro; Tomita, Hideki*; Furuya, Kazuyuki; Sato, Michitaka*; Oka, Keiichiro*; Tanaka, Teruyuki*; Takada, Fumiki; Yamamoto, Toshio*; Kato, Yoshiaki; et al.

Journal of Nuclear Materials, 343(1-3), p.285 - 296, 2005/08

https://doi.org/10.1016/j.jnucmat.2004.10.167

The dependence of helium production on radiation-hardening and -embrittlement has been examined in a reduced-activation martensitic F82H steel doped with B, B and B+B irradiated at 250C to 2.2 dpa. The total amounts of doping boron were about 60 massppm. The range of He concentration produced in the specimens was from about 5 to about 300 appm. Tensile and fracture toughness tests were performed after neutron irradiation. 50 MeV-He irradiation was also performed to implant about 85 appm He atoms at 120C by AVF cyclotron to 0.03 dpa, and small punch testing was performed to obtain DBTT. Radiation-hardening of the neutron-irradiated specimens increased slightly with increasing He production. The 100 MPam DBTT for the F82H+B, F82H+B+B, and F82H+B were 40, 110, and 155C, respectively. The shifts of DBTT due to He production were evaluated as about 70C by 150 appmHe and 115C by 300 appmHe. The DBTT shift in the small punch testing was evaluated as 50C.

Effects of helium production and heat treatment on neutron irradiation hardening of F82H steels irradiated with neutrons

Wakai, Eiichi; Taguchi, Tomitsugu; Yamamoto, Toshio*; Tomita, Hideki*; Takada, Fumiki; Jitsukawa, Shiro

Materials Transactions, 46(3), p.481 - 486, 2005/03

https://doi.org/10.2320/matertrans.46.481

no abstracts in English

Mechanical property of F82H steel doped with boron and nitrogen

Wakai, Eiichi; Matsukawa, Shingo; Yamamoto, Toshio*; Kato, Yoshiaki; Takada, Fumiki; Sugimoto, Masayoshi; Jitsukawa, Shiro

Materials Transactions, 45(8), p.2641 - 2643, 2004/08

https://doi.org/10.2320/matertrans.45.2641

no abstracts in English

Study on creep-fatigue life of irradiated austenitic stainless steel

Ioka, Ikuo; Miwa, Yukio; Tsuji, Hirokazu; Yonekawa, Minoru; Takada, Fumiki; Hoshiya, Taiji

JSME International Journal, Series A, 45(1), p.51 - 56, 2002/01

The low cycle creep-fatigue test with tensile strain hold of the austenitic stainless steel irradiated to 2dpa was carried out at 823K in vacuum. The applicability of creep-fatigue life prediction methods to the irradiated specimen was examined. The fatigue life on the irradiated specimen without tensile strain hold time was reduced by a factor of 2-5 in comparison with the unirradiated specimen. The fraction of intergranular fracture increased with increasing strain hold time. The decline in fatigue life of the irradiated specimen with tensile strain hold was almost equal to that of the unirradiated specimen. For the irradiated specimen, the time fraction damage rule trends to yield unsafe estimated lives and the ductility exhaustion damage rule trends to yield generous results. However, all of data were predicted within a factor of three on life by the linear damage rule.