Radionuclide Tracing Based in situ Corrosion and Mass Transport Monitoring of 316L Stainless Steel in a Molten Salt Closed Loop

Abstract

In the study, we report an in situ corrosion and mass transport monitoring method developed using a radionuclide tracing technique for the corrosion study of 316L stainless steel (316L SS) in a NaCl-MgCl₂ eutectic molten salt natural circulation loop. This novel method involved cyclotron irradiation of a small tube section with 16 MeV protons, later welded at the hot leg of the molten salt flow loop, generating radionuclides ${}^{51}\text{Cr}$, ${}^{52}\text{Mn}$, and ${}^{56}\text{Co}$ at the salt-alloy interface. By measuring the activity variations of these radionuclides at different sections along the loop, both the in situ monitoring of the corrosion attack depth of 316L SS and corrosion product transport and its precipitation in flowing NaCl-MgCl₂ molten salt were achieved. While 316L SS was the focus of this study, the technique reported herein can be extended to other structural materials being used in a wide range of industrial applications.