Patent Number: 
Section: claims

1. A molten fuel nuclear reactor comprising:a reactor vessel defining a reactor core configured to contain molten nuclear fuel;a first heat exchanger arranged above and in fluid communication with the reactor core to receive nuclear fuel from the reactor core;a second heat exchanger arranged above the reactor core and in fluid communication with both the first heat exchanger and the reactor core to receive nuclear fuel from the first heat exchanger and deliver nuclear fuel to the reactor core,wherein nuclear fuel delivered to the reactor core is at a lower temperature than nuclear fuel received by the first heat exchanger; anda containment vessel surrounding the reactor vessel, the first heat exchanger, and the second heat exchanger;wherein the first heat exchanger includes a shell-and-tube heat exchanger and the second heat exchanger includes a separate shell-and-tube heat exchanger. 2. The molten fuel nuclear reactor of claim 1 further comprising:one or more impellers within the containment vessel configured to drive the flow of fuel through the reactor vessel, the first heat exchanger, and the second heat exchanger. 3. The molten fuel nuclear reactor of claim 1 further comprising:a neutron shield positioned between the reactor core and the first and second heat exchangers. 4. The molten fuel nuclear reactor of claim 1 further comprising:a reflector assembly surrounding at least a portion of the reactor vessel. 5. The molten fuel nuclear reactor of claim 1 further comprising:a reflector assembly within the reactor vessel and configured to be submerged within the nuclear fuel at a periphery of the reactor core during reactor operation. 6. The molten fuel nuclear reactor of claim 1 further comprising:one or more baffles affecting nuclear fuel flow in at least one of the reactor core, the first heat exchanger, and the second heat exchanger. 7. The molten fuel nuclear reactor of claim 1 further comprising:a plenum between a nuclear fuel outlet of the first heat exchanger and a nuclear fuel inlet of the second heat exchanger. 8. The molten fuel nuclear reactor of claim 1,wherein during reactor operation natural circulation drives the flow of nuclear fuel through the reactor vessel, the first heat exchanger, and the second heat exchanger,the natural circulation created by a temperature difference between fuel in the reactor core and the lower temperature fuel exiting the second heat exchanger. 9. The molten fuel nuclear reactor of claim 1, wherein the nuclear fuel is a salt of chloride, bromide, and/or fluoride. 10. The molten fuel nuclear reactor of claim 1, wherein the nuclear fuel contains one or more of uranium, plutonium, or thorium.