Patent Number: 
Section: claims

1. A system for transferring heat from a nuclear reactor, the system comprising:a nuclear reactor comprising a nuclear fuel with a reactor core;a reactor reflector surrounding the reactor core;a reactor vessel surrounding the reactor reflector;a heat transfer system surrounding the reactor vessel, the heat transfer system comprising:an inner wall surrounding the reactor vessel;first fins directly contacting an outer surface of the inner wall;an outer wall between the inner wall and a surrounding environment; andsecond fins spaced from the first fins and directly contacting an inner surface of the outer wall and extending in a volume between the outer surface of the inner wall and the inner surface of the outer wall, the outer surface of the inner wall and the first fins configured to transfer heat from the nuclear reactor to the second fins and the inner surface of the outer wall by thermal radiation. 2. The system of claim 1, wherein the first fins comprise steel. 3. The system of claim 1, wherein the first fins comprise an integral solid core and a coating material around the core. 4. The system of claim 3, wherein the coating material comprises a different material composition than the material composition of the core. 5. The system of claim 1, wherein one or both of the first fins and the second fins exhibit a surface roughness from about 0.025 μm Ra to about 50.0 μm Ra. 6. The system of claim 1, wherein the first fins are interdigitated with the second fins such that every other fin along a circumference of the heat transfer system is a first fin and the other of the every other fins along the circumference is a second fin. 7. The system of claim 1, wherein each first fin is spaced from a neighboring first fin by from about 0.5° to about 30°. 8. The system of claim 1, further comprising heat transfer structures on an outer surface of the outer wall. 9. The system of claim 8, wherein the heat transfer structures are in contact with at least one of the ground, water, and air. 10. The system of claim 1, wherein a length of the first fins is about the same length as the second fins. 11. The system of claim 1, wherein a length of the first fins is different from a length of the second fins. 12. The system of claim 1, wherein one of the first fins and the second fins is coated with a black coating. 13. The system of claim 1, wherein the first fins comprise a different material composition than the material composition of the second fins. 14. The system of claim 1, wherein the first fins comprise one or more of iron, copper, aluminum, nickel, manganese, a cermet material, and a carbon-carbon composite material. 15. The system of claim 1, wherein the first fins comprise an alloy of one or more of iron, nickel, and manganese. 16. The system of claim 1, wherein the first fins are coated with a hydrophilic material. 17. The system of claim 1, wherein the nuclear reactor comprises one of a pebble bed reactor, a prismatic block nuclear reactor, a light water reactor, or a nuclear reactor including heat pipes.