Corrosion of EP823 Steel Cladding Under Heavy-Liquid-Metal-Coolant Reactor Conditions: A Review

The compatibility of structural materials with lead and lead-bismuth eutectic is a significant challenge in the development of fast neutron reactors with heavy-liquid-metal coolants. Liquid-metal corrosion negatively affects ferritic-martensitic steel EP823-Sh. The mechanism of liquid-metal corrosion of steels corresponds to physicochemical dissolution when the oxygen content in lead is less than the equilibrium value. The selective dissolution of steel components from the surface of the claddings is observed. When the oxygen concentration exceeds the equilibrium value, the corrosion products are the outer oxide layer of magnetite and the chromium spinel of nonstoichiometric composition such as Fe(Fe_1-x,Cr_x)₂O₄, as well as the development of an internal oxidation zone along the grain boundaries, which also can be observed. The pure-lead heat transfer sublayer between the fuel and the cladding causes the dissolution and deposition of steel components on the inner surface of the cladding. To increase corrosion resistance, it is proposed to modify the surface using plasma and laser processing, as well as by applying protective coatings.