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Effect of 20 % EDTA Aqueous Solution on Defective Tubes (Alloy600) in High Temperature Chemical Cleaning Environments
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  • Journal title : Corrosion Science and Technology
  • Volume 15, Issue 2,  2016, pp.84-91
  • Publisher : The Corrosion Science Society of Korea
  • DOI : 10.14773/cst.2016.15.2.84
 Title & Authors
Effect of 20 % EDTA Aqueous Solution on Defective Tubes (Alloy600) in High Temperature Chemical Cleaning Environments
Kwon, Hyuk-chul;
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 Abstract
The transport and deposition of corrosion products in pressurized water nuclear reactor (PWR) steam generators have led to corrosion (SCC, denting etc.) problems. Lancing, mechanical cleaning and chemical cleaning have been used to reduce these problems. The methods of lancing and mechanical cleaning have limitations in removing corrosion products due to the structure of steam generator tubes. But high temperature chemical cleaning (HTCC) with EDTA is the most effective method to remove corrosion products regardless of the structure. However, EDTA in chemical cleaning aqueous solution and chemical cleaning environments affects the integrity of materials used in steam generators. The nuclear power plants have to perform the pre-test (also called as qualification test (QT)) that confirms the effect on the integrity of materials after HTCC. This is one of the series studies that assess the effect, and this study determines the effects of 20 % EDTA aqueous solution on defective tubes in high temperature chemical cleaning environments. The depth and magnitude of defects in steam generator (SG) tubes were measured by eddy current test (ECT) signals. Surface analysis and magnitude of defects were performed by using SEM/EDS. Corrosion rate was assessed by weight loss of specimens. The ECT signals (potential and depth %) of defective tubes increased marginally. But the lengths of defects, oxides on the surface and weights of specimens did not change. The average corrosion rate of standard corrosion specimens was negligible. But the surfaces on specimens showed traces of etching. The depth of etching showed a range on the nanometer. After comprehensive evaluation of all the results, it is concluded that 20 % EDTA aqueous solution in high temperature chemical cleaning environments does not have a negative effect on defective tubes.
 Keywords
steam generator;high temperature chemical cleaning;EDTA;defective tubes;qualification test;ECT;
 Language
Korean
 Cited by
 References
1.
EPRI NP-3009, C. S. Welty, Steam Generator Chemical Cleaning Process Development (1983).

2.
ASTM E647, Standard Test Method for Measurement of Fatigue Crack Growth Rates, ASTM International (2013).

3.
J. M. Lee, S. W. Kim, S. S. Hwang, H. P. Kim and H. D. Kim, Corros. Sci. Tech., 13, 114 (2014).

4.
W. Y. Maeng, B. S. Choi, J. W. Yeon, D. W, Kang, H. B. Lee and C. S. Wang, Handbook of Water Chemistry in Nuclear Power Plant, Donghwae, KAERI (2009).

5.
EPRI TR-107207, G. L. Key, Study on High Temperature Chemical Cleaning Tests and Applications (1996).