Dissolution mechanism of 316L in lead–bismuth eutectic at 500 °C

In the frame of the Accelerator Driven System (ADS) cooled by liquid lead–bismuth eutectic (LBE), the austenitic stainless steel 316L is considered as a possible structural material for the reactor. However, the corrosion of 316L in this liquid alloy environment can be substantial, especially when a dissolution process occurs. In order to understand the dissolution process and to obtain a modelling of the 316L corrosion rate by LBE, an experimental dissolution kinetics of 316L is carried out in stagnant LBE at 500 °C up to 3000 h. A Ni preferential dissolution of the 316L is observed, leading to the formation of a ferritic layer at the 316L surface. A discussion on the various steps occurring in dissolution process leads to the conclusion that only the Ni dissolution reaction rate can control the 316L dissolution kinetics. The dissolution reaction rate constant, kd, calculated from this study experimental points is equal to 4.2 × 10−11 mol cm−2 s−1.

► 316L are corroded in LBE forming a ferritic layer caused by the preferential dissolution of Ni.
► The 316L dissolution corrosion kinetics is linear.
► The Ni diffusion in LBE is too fast to control the corrosion kinetics.
► Only the Ni dissolution reaction rate can control the corrosion kinetics.