PROTEUS-MOC在TREAT试验堆稳态中子学计算中的应用

Background: The transient reactor test facility (TREAT) is a test reactor designed to evaluate the performance of nuclear fuels and other structural materials. TREAT is characterized by its complex structure, the use of air as coolant and graphite as moderator, and strong neutron leakage and heterogeneities in both the radial and axial directions. These characteristics challenge most deterministic neutronics simulation codes. The PROTEUS-MOC code, developed at the Argonne National Laboratory in collaboration with the University of Michigan, adopts the 2D method of characteristics (MOC) and the 1D discontinuous Galerkin finite element method (FEM) to treat the radial and axial distributions of angular flux, respectively. Purpose: This study aims to evaluate the accuracy and efficiency of PROTEUS-MOC code in steady-state neutronics calculation of TREAT.Methods: The 3D TREAT model was radially discretized into unstructured mesh grids and axially discretized into a stack of planes. The macroscopic cross sections were obtained using the Serpent Monte-Carlo code. Results:PROTEUS-MOC demonstrates satisfactory precisions of eigenvalues by accurately capturing the strong neutron leakage of TREAT. Compared with the eigenvalues obtained by Monte Carlo code Serpent, the relative difference of the eigenvalues obtained by PROTEUS-MOC is merely 0.12%. Additionally, the results showed that the acceleration method TLPCMFD (two-level pCMFD) adopted in PROTEUS-MOC is very effective, speeding up the simulation by a factor of 26. Conclusions: This work demonstrates that PROTEUS-MOC is capable of producing faithful and accurate results for neutronics calculations of reactor problems with strong neutron leakage and heterogeneities.