Research on modeling and fuel performance assessing of silicon-modified ferritic-martensitic steel cladding in flowing lead–bismuth eutectic corrosion environment

Lead-bismuth coolant corrosion causes thinning of stainless steel fuel rod cladding through oxidation, dissolution, and erosion effects, thereby weakens fuel rod mechanical performance and degrades heat transfer due to its low thermal conductivity. The application of ferritic-martensitic stainless steel (F/M steel) modified with silicon can further enhance its resistance to lead-bismuth corrosion, making it an ideal cladding material choice for advanced lead-bismuth reactors. To analyze the behavior of F/M steel fuel rods under lead-bismuth corrosion conditions with higher accuracy, a silicon-modified F/M steel cladding corrosion model applicable to flowing oxygen-controlled lead-bismuth coolant environments based on previous public data is developed and subjected to preliminary validation and uncertainty analysis. Subsequently, fuel rod performance analyses are conducted under typical operating parameters of lead-bismuth reactors. The results demonstrate that silicon modified F/M steel cladding fuel rods can withstand long-term high-temperature neutron irradiation and lead-bismuth corrosion. Both steady and transient states conditions satisfy all design criteria with significant margins. Even with the upper envelope corrosion model and comparing with normal F/M steel, the calculations confirm that silicon modified F/M steel materials maintain significant corrosion resistance and high-temperature mechanical stability, capable of adapting to the operating requirements of lead-bismuth reactors under extreme conditions.