NUCLEAR TECHNIQUES, Volume. 48, Issue 7, 070017(2025)

Research on flow heat transfer characteristics of LBE in spiral-fin fuel assembly

Weihua CAI1,2, Shengcai ZHANG1,2, Siwei CAI1,2, Nianmei ZHANG3, Xian ZENG4, Xiong ZHENG4, Xiting CHEN4, Yulong MAO4, and Qian LI1,2、*
Author Affiliations
  • 1Laboratory of Thermo-Fluid Science and Nuclear Engineering, Northeast Electric Power University, Jilin 132012, China
  • 2School of Energy and Power Engineering, Northeast Electric Power University, Jilin 132012, China
  • 3School of Engineering Science, University of Chinese Academy of Sciences, Beijing 101408, China
  • 4China Nuclear Power Technology Research Institute Co., Ltd., Shenzhen 518000, China
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    Background

    The lead-cooled fast reactor, as one of the important reactor types of the fourth-generation nuclear reactor, has the potential to be widely used in nuclear-powered submarines, micro-grids, and other energy supply and power supply places.

    Purpose

    This study aims to investigate the flow heat transfer characteristics of Lead-Bismuth Eutectic (LBE) in spiral-fin fuel assembly, and provide theoretical basis and application reference for the research and design of new lead-bismuth fast reactor fuel rods.

    Methods

    Firstly, the round-rod, wire-wrap and spiral-rib 19-rod bundle fuel assembly models were built. Then, The SST k-ω two-equation turbulence model and the Cheng turbulence Prandtl number model were used to simulate the flow and heat transfer process of LBE with boundary conditions of 19.18 kg?s-1 inlet mass flow rate and 473.15 K inlet temperature. The SIMPLE algorithm was employed to calculate pressure and velocity whilst the second-order upwind scheme was used to discretize the convective term. Finally, the flow and heat transfer characteristics in the bundle fuel assemblies were analyzed in term of the temperature distribution of coolant and the heat transfer coefficient of fuel rod surface. The turbulent cross-mixing phenomenon of LBE in the fuel assembly was analyzed from the perspective of secondary flow velocity and turbulent cross-mixing coefficient.

    Results

    Compared to the round rod and wire-wrap fuel assemblies, the fluid temperature uniformity inside the spiral-fin fuel assembly is better, the surface temperature of the fuel rod is significantly lower, and the average heat transfer coefficient is significantly larger. The heat transfer coefficient of spiral-fin fuel rods decreases with the increase of the distance from the central fuel rod, and the change of the heat transfer coefficient is complex, which is difficult to fit by the correlation equation. The secondary flow velocity in the subchannel is increased significantly under the effect of spiral-fin and wire-wrap, and the velocity distribution in the spiral-fin fuel assembly and the wire-wrap fuel assembly are significantly larger than that of round rod. The secondary flow velocity distribution in the wire-wrap fuel assembly has a large velocity gradient, whereas the secondary flow velocity distribution in the spiral-fin fuel assembly is more uniform. In addition, the turbulent cross-mixing coefficient of spiral-four-fin fuel assembly is significantly larger and the LBE cross-mixing between the subchannels is superior.

    Conclusion

    The results show that the spiral-fin fuel rod has good comprehensive performance and outstanding transverse mixing characteristics, which has very good research significance and application value.

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    Weihua CAI, Shengcai ZHANG, Siwei CAI, Nianmei ZHANG, Xian ZENG, Xiong ZHENG, Xiting CHEN, Yulong MAO, Qian LI. Research on flow heat transfer characteristics of LBE in spiral-fin fuel assembly[J]. NUCLEAR TECHNIQUES, 2025, 48(7): 070017

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    Paper Information

    Category: Special Issue on The First Academic Annual Conference of the Research Reactor and Innovative Reactor Association of Chinese Nuclear Society and Advanced Nuclear Power System Reactor Engineering

    Received: Dec. 19, 2024

    Accepted: --

    Published Online: Sep. 15, 2025

    The Author Email: Qian LI (LIQian)

    DOI:10.11889/j.0253-3219.2025.hjs.48.240525

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