Te-Induced Embrittlement of Alloy 617 in Molten FLiNaK

Abstract

The present work investigates the fission product cracking problem specifically due to Te diffusion along surface grain boundaries. The material used in this study, Inconel 617, is ASME code-approved for use in high temperature reactors. The alloy samples were cold worked to 37.5%, fabricated into subsize flat tensile sample (SS3 dimensions) and exposed to FLiNaK salt in a static setup at 800 °C with Te at concentrations of 0, 0.1 or 10 wt% for 100 h. Tensile samples were strained to failure at room temperature after static exposure to determine the influence of Te on their mechanical properties. Samples were characterized via optical microscopy and scanning electron microscopy to understand associated corrosion mechanism(s), and the behavior of Te at sample surfaces and at near-surface grain boundaries. This talk will present an insight into role of Te in failure initiation and will discuss a path toward understanding the mechanical interaction of fission products with the molten salt-facing materials.