Development of techniques for electrochemical studies in power plant environments

Dissertation

Kari Mäkelä

Research output: ThesisDissertationCollection of Articles

Abstract

The properties of the oxide films on the engineering alloys used as construction materials in power plants change as a result of exposure to aqueous environments. The susceptibility of the materials to different forms of corrosion is influenced by the properties of these oxide films. The structure and electrochemical properties of the oxide films are in turn dependent on the applied water chemistry. Therefore, water chemistry control has been used in minimising the impact of different corrosion phenomena in operating power plants. Since there is not only one ideal operational specification for all light water reactors, individually designed water chemistry programs are needed to take into account plant-specific design features and particular problem areas. The applicability of alternative water chemistry practices require fast and reliable in-line electrochemical techniques to monitor possible changes in the oxidation behaviour of nuclear power plant materials. This thesis summarises the work done at the Technical Research Centre of Finland over the past 10 years to increase the knowledge of factors affecting the oxidation behaviour of construction materials in aqueous coolants at high temperatures. The work started with the development of electrodes for measurement of high temperature water chemistry parameters such as pH and the corrosion potential of construction materials. After laboratory testing these electrodes were used both in test reactors and in operating nuclear power plants. These measurements showed that high temperature water chemistry monitoring may be more accurate than corresponding room temperature measurements, particularly during transient situations. However, it was also found that understanding the processes taking place within and on oxide films requires a combination of electrochemical techniques enabling characterisation of the electronic properties of these films. This conclusion resulted in development of a controlled-distance electrochemistry arrangement. The arrangement was used to obtain data on different transport processes in the oxide films exposed to aqueous solutions. The information was then used to model the oxidation behaviour of construction materials in these solutions.
Original languageEnglish
QualificationDoctor Degree
Awarding Institution
  • University of Helsinki
Supervisors/Advisors
  • Hänninen, Hannu, Supervisor, External person
  • Beverskog, Björn, Supervisor, External person
Place of PublicationEspoo
Publisher
Print ISBNs951-38-5571-6
Electronic ISBNs951-38-5572-4
Publication statusPublished - 2000
MoE publication typeG5 Doctoral dissertation (article)

Fingerprint

Power plants
Oxide films
Water
Corrosion
Oxidation
Nuclear power plants
Electrodes
Light water reactors
Electrochemistry
Electrochemical properties
Temperature measurement
Electronic properties
Coolants
Temperature
Specifications
Monitoring
Testing

Keywords

  • power plants
  • corrosion
  • nuclear reactors
  • water chemistry
  • high temperature
  • oxide films
  • properties
  • electrodes
  • electrochemistry

Cite this

Mäkelä, K. (2000). Development of techniques for electrochemical studies in power plant environments: Dissertation. Espoo: VTT Technical Research Centre of Finland.
Mäkelä, Kari. / Development of techniques for electrochemical studies in power plant environments : Dissertation. Espoo : VTT Technical Research Centre of Finland, 2000. 174 p.
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abstract = "The properties of the oxide films on the engineering alloys used as construction materials in power plants change as a result of exposure to aqueous environments. The susceptibility of the materials to different forms of corrosion is influenced by the properties of these oxide films. The structure and electrochemical properties of the oxide films are in turn dependent on the applied water chemistry. Therefore, water chemistry control has been used in minimising the impact of different corrosion phenomena in operating power plants. Since there is not only one ideal operational specification for all light water reactors, individually designed water chemistry programs are needed to take into account plant-specific design features and particular problem areas. The applicability of alternative water chemistry practices require fast and reliable in-line electrochemical techniques to monitor possible changes in the oxidation behaviour of nuclear power plant materials. This thesis summarises the work done at the Technical Research Centre of Finland over the past 10 years to increase the knowledge of factors affecting the oxidation behaviour of construction materials in aqueous coolants at high temperatures. The work started with the development of electrodes for measurement of high temperature water chemistry parameters such as pH and the corrosion potential of construction materials. After laboratory testing these electrodes were used both in test reactors and in operating nuclear power plants. These measurements showed that high temperature water chemistry monitoring may be more accurate than corresponding room temperature measurements, particularly during transient situations. However, it was also found that understanding the processes taking place within and on oxide films requires a combination of electrochemical techniques enabling characterisation of the electronic properties of these films. This conclusion resulted in development of a controlled-distance electrochemistry arrangement. The arrangement was used to obtain data on different transport processes in the oxide films exposed to aqueous solutions. The information was then used to model the oxidation behaviour of construction materials in these solutions.",
keywords = "power plants, corrosion, nuclear reactors, water chemistry, high temperature, oxide films, properties, electrodes, electrochemistry",
author = "Kari M{\"a}kel{\"a}",
note = "Project code: V9SU00120",
year = "2000",
language = "English",
isbn = "951-38-5571-6",
series = "VTT Publications",
publisher = "VTT Technical Research Centre of Finland",
number = "415",
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}

Mäkelä, K 2000, 'Development of techniques for electrochemical studies in power plant environments: Dissertation', Doctor Degree, University of Helsinki, Espoo.

Development of techniques for electrochemical studies in power plant environments : Dissertation. / Mäkelä, Kari.

Espoo : VTT Technical Research Centre of Finland, 2000. 174 p.

Research output: ThesisDissertationCollection of Articles

TY - THES

T1 - Development of techniques for electrochemical studies in power plant environments

T2 - Dissertation

AU - Mäkelä, Kari

N1 - Project code: V9SU00120

PY - 2000

Y1 - 2000

N2 - The properties of the oxide films on the engineering alloys used as construction materials in power plants change as a result of exposure to aqueous environments. The susceptibility of the materials to different forms of corrosion is influenced by the properties of these oxide films. The structure and electrochemical properties of the oxide films are in turn dependent on the applied water chemistry. Therefore, water chemistry control has been used in minimising the impact of different corrosion phenomena in operating power plants. Since there is not only one ideal operational specification for all light water reactors, individually designed water chemistry programs are needed to take into account plant-specific design features and particular problem areas. The applicability of alternative water chemistry practices require fast and reliable in-line electrochemical techniques to monitor possible changes in the oxidation behaviour of nuclear power plant materials. This thesis summarises the work done at the Technical Research Centre of Finland over the past 10 years to increase the knowledge of factors affecting the oxidation behaviour of construction materials in aqueous coolants at high temperatures. The work started with the development of electrodes for measurement of high temperature water chemistry parameters such as pH and the corrosion potential of construction materials. After laboratory testing these electrodes were used both in test reactors and in operating nuclear power plants. These measurements showed that high temperature water chemistry monitoring may be more accurate than corresponding room temperature measurements, particularly during transient situations. However, it was also found that understanding the processes taking place within and on oxide films requires a combination of electrochemical techniques enabling characterisation of the electronic properties of these films. This conclusion resulted in development of a controlled-distance electrochemistry arrangement. The arrangement was used to obtain data on different transport processes in the oxide films exposed to aqueous solutions. The information was then used to model the oxidation behaviour of construction materials in these solutions.

AB - The properties of the oxide films on the engineering alloys used as construction materials in power plants change as a result of exposure to aqueous environments. The susceptibility of the materials to different forms of corrosion is influenced by the properties of these oxide films. The structure and electrochemical properties of the oxide films are in turn dependent on the applied water chemistry. Therefore, water chemistry control has been used in minimising the impact of different corrosion phenomena in operating power plants. Since there is not only one ideal operational specification for all light water reactors, individually designed water chemistry programs are needed to take into account plant-specific design features and particular problem areas. The applicability of alternative water chemistry practices require fast and reliable in-line electrochemical techniques to monitor possible changes in the oxidation behaviour of nuclear power plant materials. This thesis summarises the work done at the Technical Research Centre of Finland over the past 10 years to increase the knowledge of factors affecting the oxidation behaviour of construction materials in aqueous coolants at high temperatures. The work started with the development of electrodes for measurement of high temperature water chemistry parameters such as pH and the corrosion potential of construction materials. After laboratory testing these electrodes were used both in test reactors and in operating nuclear power plants. These measurements showed that high temperature water chemistry monitoring may be more accurate than corresponding room temperature measurements, particularly during transient situations. However, it was also found that understanding the processes taking place within and on oxide films requires a combination of electrochemical techniques enabling characterisation of the electronic properties of these films. This conclusion resulted in development of a controlled-distance electrochemistry arrangement. The arrangement was used to obtain data on different transport processes in the oxide films exposed to aqueous solutions. The information was then used to model the oxidation behaviour of construction materials in these solutions.

KW - power plants

KW - corrosion

KW - nuclear reactors

KW - water chemistry

KW - high temperature

KW - oxide films

KW - properties

KW - electrodes

KW - electrochemistry

M3 - Dissertation

SN - 951-38-5571-6

T3 - VTT Publications

PB - VTT Technical Research Centre of Finland

CY - Espoo

ER -

Mäkelä K. Development of techniques for electrochemical studies in power plant environments: Dissertation. Espoo: VTT Technical Research Centre of Finland, 2000. 174 p.