Long-term effects of a chemical decontamination procedure on the corrosion state of the heat exchanger tubes of steam generators

Authors

  • Andrea Szabó Nagy Department of Physics and Chemistry, University of István Széchenyi, H-9026 Győr, Hungary
  • Kálmán Varga Institute of Environmental Engineering and Radiochemistry, University of Pannonia, H-8201 Veszprém, P. O. Box: 158, Hungary
  • Bernadett Baja Institute of Environmental Engineering and Radiochemistry, University of Pannonia, H-8201 Veszprém, P. O. Box: 158, Hungary
  • Zoltán Németh Institute of Environmental Engineering and Radiochemistry, University of Pannonia, H-8201 Veszprém, P. O. Box: 158, Hungary
  • Desző Oravetz Institute of Materials Engineering, University of Pannonia
  • Zoltán Homonnay Institute of Chemistry, Eötvös Loránd University, H-1117 Budapest, Hungary
  • Ernő Kuzmann Institute of Chemistry, Eötvös Loránd University, H-1117 Budapest, Hungary
  • János Schunk Paks NPP Ltd., H-7031 Paks, P. O. Box: 71, Hungary

DOI:

https://doi.org/10.36547/nbc.1362

Keywords:

steam generators, decontamination, voltammetry, SEM-EDX, CEMS

Abstract

Our previous studies have revealed that a ”hybrid” structure of the amorphous and crystalline phases is formed in the outermost surface region of the austenitic stainless steel tubes of steam generators (SGs) as an undesired consequence of the industrial application of the AP-CITROX (AP: alkaline permanganate; CITROX: citric and oxalic acid) decontamination technology. The formation of this mobile oxide-layer increased the amount of the corrosion products in the primary circuit significantly, resulting in magnetite deposition on fuel assemblies. Owing to the fact that there is no investigation method available for the in-situ monitoring of the inner surfaces of heat exchanger tubes, a research project based on sampling as well as on ex-situ electrochemical and surface analytical measurements was elaborated. Within the frame of this project, comprehensive investigation of the general corrosion state and metallographic features of 36 stainless steel specimens, cut out from various locations of the 21 steam generators of the Paks NPP in the time period of 2000-2007 has been performed. The present work gives a brief overview on the general corrosion state of the heat exchanger tubes of SGs, concerning the long-term effects of the AP-CITROX procedure on the chemical composition and structure of the protective oxide-layer.

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Published

2022-01-13

How to Cite

Szabó Nagy, A., Varga, K., Baja, B., Németh, Z., Oravetz, D., Homonnay, Z., Kuzmann, E., & Schunk, J. (2022). Long-term effects of a chemical decontamination procedure on the corrosion state of the heat exchanger tubes of steam generators. Nova Biotechnologica Et Chimica, 7(1), 77–83. https://doi.org/10.36547/nbc.1362

Issue

Vol. 7 No. 1 (2007)

Section

Research Articles

License

Copyright (c) 2022 Andrea Szabó Nagy, Kálmán Varga, Bernadett Baja, Zoltán Németh, Desző Oravetz, Zoltán Homonnay, Ernő Kuzmann, János Schunk

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This work is licensed under a Creative Commons Attribution 4.0 International License.

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