Using half-cell potential measurement to access the severity of corrosion in reinforced concrete structures in Gentilly-2 reactor building

The half-cell potential technique has been used to assess the corrosion in the reactor's building ring beam of the Gentilly-2 nuclear power plant. It is a non-destructive technique based on the ASTM C 876 Standard. Corrosion is the result of a difference of potential between anodic and cathodic zones within the re-bars network and these potential differences are measured in the half-cell potential technique. Time exposure is the leading factor and we recommend the installation of permanent electrodes of reference in strategic areas. The results show a low corrosion activity level on 98% of the investigated surface and no severe corrosion potential reading has been registered. Furthermore the exercise shows that the repair technique has no influence on the corrosion activity of the steel network. Since most of the readings are located in the low corrosion activity level (from 0 to -100 mV), it illustrates that there is heterogeneity of the corrosion activity within the ring beam. We recommend a system to monitor the evolution of the corrosion phenomena in real time. The installation of reference electrodes positioned in some ring beam strategic areas is a simple and accurate way of monitoring the corrosion activity of the steel in the structure. In the case where an evolution in higher level is noted in the corrosion activity, it would be possible to act and prevent any further degradation of the structure