Corrosion behaviour of steel CSN 422707.9 in concentrated synthetic bentonite pore water

Concentrating of pore bentonite water as a result of water evaporation at the hot container surface is expected when the bentonite cover of the permanent nuclear waste container is being gradually saturated. The study assesses the influence of an extent of the pore water enrichment by chloride and sulphate ions up to a multiple of a hundred of their equilibrium concentration. An increase of concentration of these ions does not imply an increase of the electrolyte aggressivity automatically. A minimum of corrosion resistance was observed at triplicate concentration at all temperatures, 40, 70 and 90°C. Even more significant impact on corrosion behaviour was recognized for composition of anoxic atmosphere above the electrolyte. Contrary to nitrogen, the mixture of nitrogen and carbon dioxide remarkably elevates the electrolyte’s corrosion aggressivity.