Liquid lead-bismuth eutectic corrosion and the deposition of corrosion particles can lead to surface roughening of rod bundles, which impacts the convective heat transfer characteristics of the rod bundles. In this study, the Kays turbulent Prandtl number model and the SSTk‐ω turbulence model were validated using the existing models. Then, the validated model was used to simulate the convective heat transfer in different rough rod bundles. Based on the numerical simulation results, a new Nusselt number correlation for liquid lead-bismuth eutectic within the rough rod bundle was developed. The applicable range of the new correlation is P/D = 1.1–1.5, Pe = 400–4000, and ε/De = 0.0015–0.009. The error between the Nusselt number obtained from the correlation and the numerical simulation results is within 20 %.