Influence of Water Chemistry on the Corrosion Behaviour of the Candu Steam Generator Tubing Material - 14300

The steam generator tubes can fail by a large number of corrosion mechanisms due to the concentration of the impurities and deposits formation. In any corrosion failure, proper analytical practices and techniques will provide valuable information which, if properly understood, will lead to identification of the failure mode. It is very important to understand the generalized corrosion mechanism in the purpose to evaluate the quantities of corrosion products which exist in the steam generator after a determined period of operation. The purpose of this experimental research consists in the assessment of corrosion behavior of the tubing material (Incoloy 800) at normal secondary circuit parameters (temperature-260 deg. C, pressure-5.1 MPa). The testing environment was the demineralized water without impurities, at different pH values regulated with morpholine and cyclohexylamine (all volatile treatment - AVT). To investigate the influence of pH water chemistry on the corrosion process of tubing material, corrosion experiments by static autoclaving and electrochemical methods were performed. The results are presented like micrographies and graphics representing loss of metal by corrosion, corrosion rate, the total corrosion products, the adherent corrosion product, the released corrosion products and the release of the metal. The experimental results allowed us to establish the contribution of the pH water chemistry in evolution of the corrosion processes. (authors)