High-temperature corrosion behaviors of structural materials for lead-alloy-cooled fast reactor application

Abstract

The corrosion of nuclear-grade steels in lead–bismuth eutectic (LBE) complicates the realization of high coolant temperatures. Corrosion tests of T91, HT9, and SS316L were performed in static cells at 600◦C for 2000 h at an oxygen level of 10−6 wt.%. The obtained corrosion surfaces of post-processed samples were characterized by several microscopy methods. Up to 1000 h, all the alloys exhibited an evolution of duplex oxide layers, which were spalled until 2000 h due to their increased thickness and decreased integrity. Following the spallation, a thin internal Cr-rich oxide layer was formed above the Cr-depleted zone for T91 and HT9. SS316L was penetrated by LBE down to 300 µm in severe cases. A comparison on the corrosion depths of the materials with regard to the parabolic oxidation law with abundant literature data suggests that it may lose its validity once the duplex layer is destroyed as it allows LBE to penetrate the metal substrate.