| Project/Area Number |
10555026
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| Research Category |
Grant-in-Aid for Scientific Research (B).
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| Allocation Type | Single-year Grants |
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| Section | 展開研究 |
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| Research Field |
Materials/Mechanics of materials
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| Research Institution | TOHOKU UNIVERSITY |
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Principal Investigator |
WATANABE Yutaka Tohoku University, Guraduate School of Engineering, Associate Professor, 大学院・工学研究科, 助教授 (10260415)
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| Co-Investigator(Kenkyū-buntansha) |
SUZUKI Shunichi Tokyo Electric Power Company, Power Engineering R&D Center, Senior Researcher, 電力技術研究所, 主任研究員
HARA Nobuyoshi Guraduate School of Engineering, Associate Professor, 大学院・工学研究科, 助教授 (40111257)
SHOJI Testuro Tohoku University, Guraduate School of Engineering, Professor, 大学院・工学研究科, 教授 (80091700)
KAWAMURA Hirotaka Central Research Institute of Electric Power Industry, Komae Research Laboratory, Senior Researcher, 狛江研究所, 主任研究員
OONAKA Noriyuki Hitachi Kyowa Engineering, Ltd., Analysis Center, Principal Engineer, 分析センター, 副技師長(研究職)
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| Project Period (FY) |
1998 – 2000
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| Project Status |
Completed (Fiscal Year 2000)
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| Budget Amount *help |
¥8,100,000 (Direct Cost: ¥8,100,000)
Fiscal Year 2000: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 1999: ¥4,000,000 (Direct Cost: ¥4,000,000)
Fiscal Year 1998: ¥3,000,000 (Direct Cost: ¥3,000,000)
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| Keywords | electrochemical noise / stress corrosion cracking / pressurized water reactor / boiling water reactor / stainless steel / Ni-base alloy / current noise / potential noise / 界面反応 |
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| Research Abstract |
1. Testing facilities were developed to monitor electrochemical noise generating during stress corrosion cracking(SCC)processes of alloys in simulated LWR coolant environments. In particular, ground loop problems and fluctuation in pressure, which can cause electrochemical noise, were solved and successful monitoring of electrochemical noise with high sensitivity was achieved.
2. The three electrodes method, which consists of a working electrode(specimen), a counter electrode made of the identical material to the specimen, and a reference electrode, was adopted to simultaneously monitor fluctuations of coupling current and of corrosion potential. It was successfully demonstrated that SCC initiation in pressurized high-temperature water can be detected with high sensitivity by this method.
3. Based on current noise analysis, the slip dissolution mechanism was supported for SCC of sensitized stainless steels in a simulated boiling water reactor(BWR)environment.
4. As for SCC of Ni-base Alloy 600 in primary water of pressurized water reactor(PWR), cathodic current spikes were superimposed on anodic current spikes, indicating that both anodic dissolution of metal and cathodic reaction(hydrogen generation)were enhanced on bare metal surface produced by mechanical film rupture. This fact supports either the slip dissolution mechanism or hydrogen cracking.
5. It was found that excess electrons produced by transient anodic dissolution of metal were temporarily accumulated at double layer capacitance of metal-water interface. This fact implies that relatively large anodic event can take place, if that is a transient event, even in the primary water environment, where concentration of oxidizer is very low.
6. A concept of multiple counter electrodes method was devised for monitoring of SCC initiation in plant components and validity of the concept was demonstrated by a model experiment.
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