SAM is a MOOSE-based, fast-running, whole-plant transient analysis capability with improved-fidelity for advanced reactors, including SFR, LFR, and MSR/FHR concepts. It takes advantage of advances in physical modeling, numerical methods, and software engineering to provide a robust and high-order FEM model of single-phase fluid flow and heat transfer for component-based system modeling. The flexible coupling between fluid and solid components allows for flexible modeling using single- or multi-channel representation of fuel assemblies with automatically generated core lattice including the inter-assembly structures. The coupling interfaces allow for easy integration with other advanced or conventional simulation tools for multi-scale and multi-physics modeling capabilities. SAM also features a reduced-order multidimensional flow model to model thermal mixing and stratification phenomena in large enclosures for safety analyses.