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Ugachi, Hirokazu; Kaji, Yoshiyuki; Nakano, Junichi*; Matsui, Yoshinori; Kawamata, Kazuo; Tsukada, Takashi; Nagata, Nobuaki*; Dozaki, Koji*; Takiguchi, Hideki*
Proceedings of 12th International Conference on Environmental Degradation of Materials in Nuclear Power Systems-Water Reactors (CD-ROM), p.319 - 325, 2005/00
Irradiation assisted stress corrosion cracking (IASCC) is one of the critical concerns when stainless steel components have been in service in light water reactors (LWRs) for a long period. In the research field of IASCC, mainly PIEs for irradiated materials have been carried out, because there are many difficulties on SCC tests under neutron irradiation. Hence as a part of the key techniques for in-pile SCC tests, we have embarked on a development of the test technique to obtain information concerning effects of applied stress level, water chemistry, irradiation conditions, etc. In this conference, we describe the developed several techniques, especially control of loading on specimens, monitoring technique of crack initiation, propagation and water chemistry, and the current status of in-pile SCC tests using thermally sensitized materials at JMTR.
Uchida, Shunsuke*; Sato, Tomonori; Morishima, Yusuke*; Hirose, Tatsuya*; Miyazawa, Takahiro*; Kakinuma, Nagao*; Sato, Yoshiyuki*; Usui, Naoshi*; Wada, Yoichi*
Proceedings of 12th International Conference on Environmental Degradation of Materials in Nuclear Power Systems-Water Reactors (CD-ROM), p.19 - 29, 2005/00
Static and dynamic responses of stainless steel specimens exposed to H
O and O in high temperature water were evaluated by analyzing ECP and FDCI (frequency dependent complex impedance). The oxide films on the specimens were characterized by multilateral surface analyses, e.g., LRS, SIMS, XPS and direct electric resistance measurement. As a result of evaluation, it was confirmed that (1) corrosive condition of BWR normal water chemistry (NWC) was simulated by 100 ppb HO without co-existing O, while that of hydrogen water chemistry (HWC) was simulated by 10 ppb HO, (2) ECP under HWC was as high as that under NWC, while dissolution rate of oxide film under HWC was much lower than that under NWC, (3) combination effects of electric resistance and dissolution rate of oxide caused same level ECP for both NWC and HWC, and (4) distinct weight loss of the specimen exposed to 100 ppb HO was observed.
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.