1999 Fiscal Year Final Research Report Summary
Study on New Water Chemistry Control for Stabilization of Oxide Films in Coolant Systems of Light Water Reactors
| Project/Area Number |
09558057
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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 |
エネルギー学一般・原子力学
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| Research Institution | The University of Tokyo |
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Principal Investigator |
ISHIGURE Kenkichi Graduate School of Engineering, the University of Tokyo, Professor, 大学院・工学系研究科, 教授 (90010975)
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| Co-Investigator(Kenkyū-buntansha) |
HIROISHI Daisuke Graduate School of Engineering, the University of Tokyo, Research Associate, 大学院・工学系研究科, 助手 (20199110)
ASAI Keisuke Graduate School of Engineering, the University of Tokyo, Associate Professor, 大学院・工学系研究科, 助教授 (60231859)
KATSUMURA Yousuke Graduate School of Engineering, the University of Tokyo, Professor, 大学院・工学系研究科, 教授 (70111466)
ONO Shoichi Institute of Research and Innovation, Researcher, 研究員
HENMI Yukio Toshiba Corp. Nuclear Technology Institute, Senior Researcher, 原子力技術研究所, 主幹
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| Project Period (FY) |
1997 – 1999
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| Keywords | light water reactor / water chemistry / zinc injection / corrosion product / oxide film / stress corrosion cracking / hydrogen injection / noble metal chemical addition |
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| Research Abstract |
The present status of water chemistry in Japanese LWR was widely reviewed from literature and discussion with relevant experts. Then zinc injection and noble metal chemical addition were picked up as major subjects in this project.
It was shown experimentally and analytically that zinc ion injected forms complex ferrites and chromites as a result of interaction with Fe and Cr ions, respectively, on the surfaces of stainless steel and fuel cladding and that cobalt accumulation in the inner oxide layer (chromites) on the surface of stainless steel is suppressed effectively by zinc injection while it is not necessarily effective for the suppression of cobalt pick-up in the outer layer (ferrites).
The experimental result showed that zinc injection forms very thin inner oxide layer of zinc chromite that is very stable thermodynamically and thus reduces remarkably the corrosion of stainless steel, consequently being effective for reducing the cobalt accumulation.
It was also shown experimentall
… More
y that Cr(VI) ion in aqueous phase oxidizes Zr on contacting with Zircaloy and is precipitated on its surface as amorphous Cr(III) oxides in the absence of zinc ion but as crystaline zinc chromite in the presenee of zinc ion. This Cr deposition is considered to be closely related with cobalt dissolution from the surface deposits of the fuel and was found to be remarkably suppressed by the pre-conditioning of the Zircaloy.
Platinum injection is now expected to make hydrogen injection more effective in BWR, and the chemical behavior of a tetra-ammine complex of Pt(II) and hexa-hydroxo-complex of Pt(IV) was investigated in aqueous solutions under gamma-irradiation.
The Pt(II) complex is easily reduced and forms Pt metal in aqueous phase by heating to 120 〜 150 ℃ while the Pt(IV) complex is not reduced and consequently does not form Pt metal only by the heating. Gamma irradiation readily reduces both of the Pt complexes to Pt metal in the presence of HィイD22ィエD2 or alcohols, but not in the presence of OィイD22ィエD2. The diameters and the catalytic property of the small particles of Pt metal formed were found to be largely affected by the condition of the particle preparation. This result shows that the effect of radiation is very important in the noble metal addition in real plants. Less
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