Molten salt nuclear reactors (MSRs) constitute a promising technology to produce safe, reliable, abundant low-carbon energy. To design MSR systems and perform safety analyses on them, numerical simulation is a powerful tool. Here we implemented a coupling between several solvers of the deterministic neutronics code APOLLO3 ® (the MINARET S N-transport and the MINOS diffusion and SP n-simplified-transport solvers) and the computational fluid dynamics (CFD) code TRUST/-TrioCFD, both developped at the French Alternative Energies and Atomic Energy Commission (CEA). The code-coupling is orchestrated using the dedicated C3PO library of the open-source SALOME platform. A new code-coupling strategy is employed whereby the delayed neutron precursor concentrations are computed by the CFD code, which eases the use of traditional deterministic neutronics codes. We verified the correctness of our implementation by performing a numerical benchmark dedicated to fast-spectrum MSRs originally devised by the French National Center for Scientific Research (CNRS). The numerical results we obtained are in excellent agreement with those obtained by recent MSR-dedicated multi-physics simulation tools. This study provides a new convenient neutronic-thermalhydraulic coupling strategy for MSR core simulation.