Corrosion of steel liners inside concrete structures is one of the concerns in the aging management of Nuclear Power Plants (NPP). WP2 of the ACES project is addressing two cases where safety is the major challenge: chloride-induced corrosion of Steel Cylinder Concrete Pipes (SCCP) and crevice corrosion of steel liner embedded in the concrete of containment building.
One of the tasks within WP2 is investigating the strengths and limitations of commercially available non-destructive testing techniques (NDTs) which could be used with a robotic manipulator for early detection of corrosion damages inside SCCP.
Half-cell potential mapping was identified as potentially suitable NDT according to relevant criteria. The figure is showing (a) the mould with steel liner before casting; (b) casting in concrete with mixed-in chlorides; (c) measuring potentials in matrix 8 x 8; (d) half-cell potentials [mV] after 89 days of exposure to wet/dry cycles – more negative values = more corrosion active spot.