Long-Term Behaviors of Oxide Layer in Liquid Lead–Bismuth Eutectic (LBE), Part II: Model Applications

Abstract

This article is Part II of the systematic study on the long-term behaviors of the protective oxide layer in liquid lead–bismuth eutectic (LBE) systems. The model developed in Part I is applied to analyze the kinetics of the growth of the oxide layer formed on cladding materials (HT-9 and T-91 steel) of an LBE-cooled small modular reactor. It is found that the outer magnetite layer of initially formed duplex-layer oxide structure on cladding steels can be completely removed in a long-term operation through chemical reaction with the liquid metal and mass transfer by the liquid metal flow, which causes the inner compact spinel layer to contact with LBE directly. The present calculations indicate that the corrosion rate of the steels considered is reduced by approximately three orders of magnitude after the magnetite layer is removed. Increasing the velocity of the LBE flow can reduce the time needed for removal of the magnetite layer, which benefits the steel corrosion resistance for a long-term operation. The oxide layer properties and growth kinetics are also analyzed. The operation ranges of the flow velocity and the oxygen concentration are developed based on the modeling results, which indicates both T-91 and HT-9 have appropriate corrosion resistance and can be applied as cladding materials for a 10-year operation if the oxygen concentration is well controlled.