Development and validation of fully-coupled subchannel analysis code for LMR within the MOOSE framework

As one of the Gen IV advanced reactors, liquid metal reactor (LMR) holds promising prospects for its high fuel efficiency and excellent inherent safety performance. Owing to its complex working conditions and ultra-high operating temperature, a thermal–hydraulic analysis of the reactor core is gradually playing a bigger role in recent years. Therefore, a subchannel code FLARE for LMRs has been developed within the Multiphysics Object-Oriented Simulation Environment (MOOSE) Framework, accompanied by the physical models tailored for LMRs embedded in FLARE. Additionally, a hybrid discretization approach involving the Discontinuous Galerkin (DG) and Finite Element Method as well as the Jacobian-Free Newton-Krylov (JFNK) method are employed to solve the equations in a fully-coupled way. To validate the computational convergence of FLARE code under low flow rate conditions, the 7-pin experiment is adopted. The results exhibit that the absolute errors between the computed values and experimental data for the majority of calculation points are within 5 K. Furthermore, comparisons between the calculation values of FLARE (Fully-coupled transient code for Liquid-metal-cooled Advanced REactor), those of other programs and the experimental data are performed using 19-pin and 37-pin assembly experiments. The computational results indicate a good agreement between FLARE, experimental values, and other programs. In conclusion, FLARE code possesses the capability to accurately analyze the LMR core, which may provide new ideas for in-depth coupling research based on MOOSE.