Techniques for Measuring and Optimizing Dissolved Oxygen Concentration in a Liquid Lead Environment

Owing to their superior thermal conductivity, heavy liquid metals (HLMs) are becoming increasingly important as heat transfer and storage media in energy-related technologies such accelerator-driven systems, generation IV (GEN IV) fast reactors, and concentrating solar energy. Molten lead and lead-bismuth eutectic (LBE) are examples of HLM that are aggressive against structural materials, which is one of its main drawbacks. Steel alloying elements’ high solubility in lead (Pb) or LBE at high temperatures can cause HLM to selectively dissolve and penetrate, along with structural and phase changes, a decline in mechanical characteristics, and eventually failure. The existence of dissolved oxygen in the liquid metal phase has a significant impact on steel’s performance in liquid metals. A continuous layer made of the oxides of the steel’s constituent elements may form on its surface if the oxygen content rises above a particular point, separating the steel from the liquid metal. Thus, diffusion through the oxide layer is required for the primary degrading mechanism of the liquid metal phase at low oxygen content, which is the dissolving of steel components. This paper aims to highlight the effects that dissolved oxygen has on liquid lead, to explain the need to monitor the residual oxygen concentration in the liquid metal, and also to present the main types of sensors with which this monitoring is done.