Fuel assemblies have a decisive impact on the performance and safety of nuclear reactors.Helical fuel has huge potential for application in small module reactors(SMRs)due to its advantages in volume power density and ...Fuel assemblies have a decisive impact on the performance and safety of nuclear reactors.Helical fuel has huge potential for application in small module reactors(SMRs)due to its advantages in volume power density and safety.Typical helical fuel elements are usually trilobal or cruciform in cross-section.The fuel rods are helically twisted in the axial direction,eliminating the need for spacer grids as the fuel rods are self-supporting.In this paper,a refined subchannel division approach is proposed based on the crossflow mechanism of helical fuel assemblies.Then,a refined helical fuel mixing model framework,including the helical fuel distributed resistance method and directed crossflow method,is developed and implemented in a helical fuel rod bundle to investigate the mixing characteristics.Validation is provided by a 5×5 helical fuel bundle mixing experiment.The refined model predicts about 92.7%of the data with the±10%error range.Compared with existing helical fuel mixing models,the refined mixing model has higher axial accuracy and radial spatial resolution,and can accurately predict the twist angledependent crossflow rate and entry effect.Meanwhile,the refined helical fuel mixing model framework is universal and can be effectively used for the mixing prediction of arbitrary geometric helical fuel after the calibration of coefficients.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos.12135008,12075150,and 12275174)the Shanghai Rising-Star Program (Grant No.22QA1404500)the Jingying Project of China National Nuclear Corporation。
文摘Fuel assemblies have a decisive impact on the performance and safety of nuclear reactors.Helical fuel has huge potential for application in small module reactors(SMRs)due to its advantages in volume power density and safety.Typical helical fuel elements are usually trilobal or cruciform in cross-section.The fuel rods are helically twisted in the axial direction,eliminating the need for spacer grids as the fuel rods are self-supporting.In this paper,a refined subchannel division approach is proposed based on the crossflow mechanism of helical fuel assemblies.Then,a refined helical fuel mixing model framework,including the helical fuel distributed resistance method and directed crossflow method,is developed and implemented in a helical fuel rod bundle to investigate the mixing characteristics.Validation is provided by a 5×5 helical fuel bundle mixing experiment.The refined model predicts about 92.7%of the data with the±10%error range.Compared with existing helical fuel mixing models,the refined mixing model has higher axial accuracy and radial spatial resolution,and can accurately predict the twist angledependent crossflow rate and entry effect.Meanwhile,the refined helical fuel mixing model framework is universal and can be effectively used for the mixing prediction of arbitrary geometric helical fuel after the calibration of coefficients.
