In an embodiment, example fast neutrons 1114 emanating from fuel region 1102 may be reflected by flowing reflecting liquid 1104 contained in tubes 1008 or be reflected by flowing reflecting liquid 1104 contained in channels 1110, and back into fuel region 1102. Fast neutrons such as example fast neutron 1116 emanating from molten fuel salt flowing in channels 1112 may also be reflected by flowing reflector material 1104 in tubes 1108 or in channels 1110, and back into fuel region 1102.
FIG. 12 depicts a flow diagram of example operations 1200 of dynamic spectrum shifting in a molten nuclear fuel salt fast reactor. A sustaining operation 1202 sustains a nuclear fission reaction in a nuclear reactor core surrounded by a dynamic neutron reflector assembly. The neutron reflector assembly may have at least one neutron reflector material. A neutron reflection assembly may surround a nuclear reactor core by being disposed radially around, above, and/or below the reactor core. The neutron reflection assembly may be formed in one contiguous piece, formed into discrete pieces distributed around the reactor core, disposed around the core in discrete pieces with gaps in between, and/or segmented into regular or irregular sections. The reflection assembly may contain one or more channels for conducting a flowing reflector material. The reflection assembly may contain one or more levels of channels, such that a flowing reflector material flows in one direction in one level, and flows in another direction in one or more other levels. For example, the reflection assembly may contain an outer channel with flowing reflector material flowing downward, and another inner channel with flowing reflector material flowing upward to avoid any inlet or outlet plumbing underneath the reactor core.
