Fig. 1: Limitations of existing experiment-oriented oxygen control strategies and conceptual framework for establishing a safety-oriented oxygen control strategy in LFR.
Key experimental results with corrosion duration exceeding 1000 h are presented in a, b, with marker colour representing oxide layer thickness11. a Existing oxygen control strategy for LFR are based on the oxidation corrosion theory, since the bioxide layer plays a crucial role in protecting nuclear fuel rod from LBE corrosion. The oxygen control window is defined by the red and blue curves, calculated from equations (S49) and (S50) in Supplementary Note B. The red curve denotes the threshold above which lead oxide deposition occur, while the blue curve represents the minimum oxygen concentration required for magnetite stability. However, experimental findings reveal that oxidation protection failure (represented in dark blue points) and excessive oxide layer growth (represented in dark red points) may occur even within the recommended oxygen concentration range11. Additionally, the oxygen concentration required for oxidation protection increases significantly with rising temperatures11,14,15,16,17. b Liquid LBE flow corrosion experiments have demonstrated a thinning of the oxide layer with increasing flow velocity11. Given the non-uniformity of temperature and flow velocity distributions within the reactor core, oxygen control strategies should account for the full spectrum of key operating conditions. c By constructing the K2K surrogate model, predictions of fuel performance across the primary design domain are achieved using a limited dataset. The K2K predictions enable the identification and localization of cladding failure modes. Additionally, KAN facilitates the derivation of a formalized optimal oxygen concentration control strategy.
