Supercritical water use in energetic - Corrosion issues

Supercritical water (SCW) is water at conditions above the critical point (typically 600°C, 25 MPa). SCW is used as coolant in the primary circuit of one of the new concepts of nuclear reactors. Supercritical water has unique properties and very low price enables its use as chemical environment as well as reactant taking part in chemical reactions. These reactions lead to very interesting products (i.e. nanocrystals). SCW can be use for toxic waste elimination, or as medium for biomass gasification. One of the biggest problems associated with SCW usage is its corrosive action, putting therefore high demands on constructional materials. Harsh conditions cause the change in mechanical properties (creep, swelling) as well. Characterization of electrochemical corrosive action of SCW (if any) is problematic due to the rapid decrease of density and dielectric constant. Nevertheless, corrosion clearly takes place in the system, with high corrosion rate. This article deals with corrosion monitoring in SCW.