Temperature induced cathode-anode reversal behavior of TA2–304 L galvanic couple in simulated spent fuel reprocessing media

Abstract

Galvanic corrosion is prevalent throughout various stages of spent fuel reprocessing, and plays a crucial role in the corrosion failure of equipment materials due to its pronounced local corrosive effects. Nevertheless, there is a scarcity of systematic investigations regarding the impact of temperature on the corrosion mechanism of galvanic couples in simulated spent fuel reprocessing media. This study aims to explore the electrochemical behavior and passive film characteristics of TA2–304 L galvanic couple immersed in nitric acid solutions at different temperatures. Relevant results indicated that temperature significantly affected the galvanic corrosion behavior of TA2–304 L couple in nitric acid. The galvanic couple demonstrated a notable reversal in cathodic and anodic polarity with the rising temperature, which was closely related to the changed corrosion mechanism of 304 L SS from superior passivation performance to severe intergranular corrosion. Meanwhile, a critical temperature phenomenon was observed for TA2, below which there exhibited a monotonically decreased corrosion resistance with the increase in temperature. However, an improved corrosion resistance was found as the temperature rose to 120 °C, which could be associated with the decreased oxidative properties of nitric acid because of the variation in electrochemical/chemical reactions. Additionally, the relationship between corrosion rate and temperature of both 304 L SS and TA2 was created, and the activation energy was calculated to stress the influence of temperature on the corrosion of both materials. Eventually, the galvanic mechanism of TA2–304 L couple with temperature in nitric acid was proposed.