FIG. 4 illustrates an MSR system 400 with a dynamic flowing neutron reflector assembly 406 equipped with a spillover reservoir 408. A molten fuel salt 402 flows in an upward direction as it is heated by the fission reaction in the internal central reactor core section and flows downward as it cools around the internal periphery of the reactor vessel 401. In FIG. 4, hollow tip arrows indicate the flow of molten fuel salt through MSR system 400. The constituent components of the molten fuel may be well-mixed by the fast fuel circulation flow (e.g., one full circulation loop per second). In one implementation, one or more heat exchangers 404 are positioned at the internal periphery of the reactor vessel 401 to extract heat from the molten fuel flow, further cooling the downward flow, although heat exchangers may additionally or alternatively be positioned outside the reactor vessel 401.
