FIG. 26 illustrates another embodiment of a heterogeneous reflector configuration for a molten nuclear fuel salt reactor. FIG. 26 illustrates a reactor 2600 with a graphite-backing configuration in which a relatively thin graphite layer 2602 is provided outside of a lead reflector 2604 which surrounds the reactor core 2606.
FIG. 27 illustrates yet another embodiment of a heterogeneous reflector configuration for a molten nuclear fuel salt reactor. FIG. 27 illustrates a reactor 2700 with a graphite-fronting configuration in which a relatively thin graphite layer 2702 is provided next to the reactor core 2706 and between the core and the lead reflector 2704.
FIG. 28 illustrates a comparison of the modeled effect on reactivity of graphite-fronting and graphite-backing embodiments similar to those shown in FIGS. 26 and 27. In the modeling, graphite-fronting and graphite-backing embodiments of a reactor are modeled and the only variable changed besides the location of graphite layer is the thickness of the graphite layer relative to the thickness of the lead reflector layer. As can be seen, there is a significant difference in reactivity between the two embodiments. This means that each configuration has different reactivity characteristics, which allows other aspects of the reactor to be optimized such as reactor core size and, thus, the volume of fuel salt required for criticality. For example, graphite-fronting embodiments have generally higher reactivity, which allows a smaller reactor core to be used.
