High-fidelity　analysis　of　nuclear　reactors　is　beneficial　to　improving　the　efficiency　of　nuclear　reactor　designs.　To　enhance　modeling　fidelity,　multi-physics　coupling　simulations　are　typically　employed.　To　this　end,　several　platforms　for　code　coupling　are　under　active　development,　including　MOOSE,　SALOME,　et　al.　In　this　paper,　the　loosely　coupling　interface　between　MOOSE　and　OpenFOAM　was　developed,　aiming　to　extend　the　Computational　Fluid　Dynamics　(CFD)　capacity　for　MOOSE.　Specifically,　process　control,　data　transfer,　and　mesh　projection　of　the　coupled　simulation　are　realized　by　the　MultiApps　and　Transfers　module　within　MOOSE　and　the　externalCoupled　module　within　OpenFOAM,　where　text-based　data　transfer　is　used.　The　CFD　capabilities　of　OpenFOAM　and　the　finite　element　analysis　capabilities　of　MOOSE　are　fully　utilized　in　this　coupling　environment.　Subsequently,　a　conjugated　heat　transfer　problem　for　plate　fuel　was　conducted　to　demonstrate　the　feasibility　of　the　developed　interface,　where　variables　consisting　of　temperature,　convective　heat　transfer　coefficient,　and　heat　flux　at　outer　surfaces　are　transferred　between　MOOSE　and　OpenFOAM.　The　predicted　results　of　the　plate　fuel　seem　reasonable　and　the　validity　of　the　novel　coupling　code　for　MOOSE　and　OpenFOAM　is　preliminary　confirmed.　©　2022　by　ASME.