Patent Number: 
Section: claims

1. A composition comprising a halide salt matrix having dispersed therein nanoparticles comprising elemental carbon in the absence of water and surfactants, wherein said halide salt is an alkali halide salt, alkaline earth halide salt, or combination thereof, and said halide is fluoride or chloride. 2. The composition of claim 1, wherein said halide salt contains at least one alkali halide salt selected from the group consisting of lithium fluoride, sodium fluoride, potassium fluoride, rubidium fluoride, sodium chloride, potassium chloride, rubidium chloride, and eutectic mixtures thereof. 3. The composition of claim 1, wherein said nanoparticles comprising elemental carbon are selected from the group consisting of hollow carbon nanospheres, exfoliated graphite nanoplatelets, carbon nanotubes, spherical fullerenes, carbon black, carbon nanodiamonds, carbon onions, carbon nanofibers, graphene oxide nanoparticles, reduced graphene oxide nanoparticles, and metal carbide nanoparticles. 4. The composition of claim 1, wherein said composition further comprises nanoparticles comprising a fissile material dispersed within said composition. 5. The composition of claim 4, wherein said fissile material comprises uranium, thorium, or plutonium. 6. The composition of claim 1, wherein said nanoparticles comprising elemental carbon contain a core of a metal encapsulated by a shell of carbon. 7. The composition of claim 6, wherein said metal is a fissile material. 8. The composition of claim 7, wherein said fissile material comprises uranium, thorium, or plutonium. 9. A molten salt reactor comprising (i) a reactor core in which fissile material is housed and (ii) a coolant loop containing a molten salt composition, wherein said coolant loop is within sufficient proximity to said reactor core so as to remove heat from said reactor core and maintain said reactor core within a safe operating temperature, and wherein said molten salt composition comprises a halide salt matrix having dispersed therein nanoparticles comprising elemental carbon in the absence of water and surfactants, wherein said halide salt is an alkali halide salt, alkaline earth halide salt, or combination thereof, and said halide is fluoride or chloride. 10. The molten salt reactor of claim 9, wherein said coolant loop is a primary coolant loop. 11. The molten salt reactor of claim 10, wherein said primary coolant loop is within sufficient proximity to a secondary coolant loop so as to permit said secondary coolant loop to remove heat from said primary coolant loop. 12. The molten salt reactor of claim 11, wherein said secondary coolant loop contains water or supercritical carbon dioxide. 13. The molten salt reactor of claim 9, wherein walls of said coolant loop in contact with the molten salt are constructed of stainless steel. 14. The molten salt reactor of claim 9, wherein said halide salt contains at least one alkali halide salt selected from the group consisting of lithium fluoride, sodium fluoride, potassium fluoride, rubidium fluoride, sodium chloride, potassium chloride, rubidium chloride, and eutectic mixtures thereof. 15. The molten salt reactor of claim 9, wherein said nanoparticles comprising elemental carbon are selected from the group consisting of exfoliated graphite nanoplatelets, carbon nanotubes, spherical fullerenes, carbon black, carbon nanodiamonds, carbon onions, carbon nanofibers, graphene oxide nanoparticles, reduced graphene oxide nanoparticles, and metal carbide nanoparticles. 16. The molten salt reactor of claim 9, wherein said composition further comprises nanoparticles comprising a fissile material dispersed within said composition. 17. The molten salt reactor of claim 16, wherein said fissile material comprises uranium, thorium, or plutonium. 18. The molten salt reactor of claim 9, wherein said nanoparticles comprising elemental carbon contain a core of a metal encapsulated by a shell of carbon. 19. The molten salt reactor of claim 18, wherein said metal is a fissile material. 20. The molten salt reactor of claim 19, wherein said fissile material comprises uranium, thorium, or plutonium. 21. The composition of claim 1, wherein said nanoparticles comprising elemental carbon are hollow carbon nanospheres. 22. The composition of claim 1, wherein said halide salt matrix contains a combination of an alkali halide salt and alkaline earth halide salt. 23. The composition of claim 1, wherein said composition excludes carbon nanotubes.