Three-Dimensional Refined Burnup Calculation of Helical-Cruciform Nuclear Fuel

Abstract The Helical Cruciform Nuclear fuel (HCF) is an Advanced Technology of Fuel (ATF), a low-enriched uranium fuel has been proposed by Lightbridge. The innovation of HCF lies in the use of metallic materials and the geometry is a petal-shaped cross-section and axial twist. HCF proposes higher requirements and challenges for predicting the three-dimensional neutron physics characteristics in different burnup with high fidelity, especially in the three-dimensional geometric model and burnup region division. An introduction of refined three-dimensional burnup characteristic analysis method for HCF is proposed in which the HCF is divided into several hexahedral solid burnup regions and the geometric model established based on DAGMC. OpenMC is used for the coupled neutron transport and burnup calculations. The results show that in the circumferential and axial directions, neutron physics variables are inhomogeneous and asymmetric due to the petal-shaped cross-section and the axial twist. There is a greater effect by twist on the axial power density at convex position compared to concave position. With increasing burnup time, the change in power density at convex position is larger than that at concave position, which increases the inhomogeneity of circumferential power density. The refined three-dimensional burnup analysis method provides a refined spatial distribution of physical parameters under different burnup, enhancing the potential and accuracy of coupled calculations in neutron physics, thermal-hydraulics, mechanics, and other aspects.