ABSTRACT
Growth of thermally formed oxides, dissolution of oxides and deposition of corrosion products play an important role in the performance of power cycles. Regarding the secondary side of PWR plants, corrosion concerns are typically associated with the integrity of the steam generator. Localised forms of corrosion in crevices and under deposits are considered to be potentially hazardous and are directly related to secondary circuit chemistry. The contribution of in-situ applied electrochemical techniques, especially corrosion potential and polarisation measurements, for corrosion studies in the light water reactor environment is covered in the comprehensive review of Turnbull and Psaila-Dombrowski [1]. AC techniques can provide additional information about the electronic properties and morphology of the oxide layer and about charge and mass transfer phenomena [2]. New techniques such as contact resistance (CR) or contact electrical impedance (CEI) [3] enable in-situ estimation of oxide resistivity, while controlled distance electrochemistry (CDE) and its derivative thin layer electrochemical impedance spectroscopy (TLEIS) allow for electrochemical measurements in high resistivity media such as boiling water reactor (BWR) coolant [4]. Electrochemical noise (EN) is another prospective electrochemical technique employed for characterisation of corrosion phenomena in the high-temperature environment. EN measurements were used, for example, to detect stress corrosion cracking initiation in BWR media [5].
