Fast reactors that circulate liquid fuel exhibit a strong coupling between neutronics and thermalhydraulics (THs) that necessitates the use of coupled multi-physics codes to study dynamic behaviour. Presently, most such tools employ computational fluid dynamics (CFD) to resolve THs. This paper concerns an alternative approach in which the system code TRACE is used to compute two-dimensional flow patterns and temperature distributions of liquid-fuel fast reactors using coarse meshes and a simplified set of equations. As such, computational requirements are greatly reduced compared to CFD-based solvers. In the coupled tool, the TH variables are sent to the spatial neutronics solver PARCS that calculates power using cross-sections from the Serpent Monte Carlo code. We report the application of TRACE-PARCS to the primary and secondary circuits of the Molten Salt Fast Reactor, and compare the results with alternative multi-physics tools. Reasonable agreement is found, which paves the way for whole-plant simulations including tertiary turbine circuits.