Patent Number: 
Section: claims

1. A molten fuel nuclear reactor comprising:a containment vessel and vessel head;a reactor core enclosed within the containment vessel and vessel head, the reactor core having an upper region and a lower region;a heat exchanger enclosed within the containment vessel and vessel head, the heat exchanger fluidly connected to the upper region of the reactor core by an upper channel and fluidly connected to the lower region of the reactor core by a lower channel, the reactor core, heat exchanger and upper and lower channels forming a fuel loop;a reflector defining the lateral extent of the reactor core, the reflector adjacent to the heat exchanger and separating the reactor core from the heat exchanger, wherein the upper channel is above the reflector and the lower channel is below the reflector; andan impeller enclosed within the containment vessel and vessel head, the impeller attached to a shaft that is rotatable by a motor located outside of the containment vessel and vessel head;wherein the impeller is located within the fuel loop such that the impeller, when rotated by the motor, circulates fluid through the fuel loop;wherein the reflector has a top defined by the upper channel and a bottom defined by the lower channel and the impeller is located below the top of the reflector and above the heat exchanger. 2. The molten fuel nuclear reactor of claim 1, wherein the shaft penetrates the vessel head and rotatably connects the impeller to a motor located above the vessel head. 3. The molten fuel nuclear reactor of claim 1, wherein the impeller is located in the upper channel. 4. The molten fuel nuclear reactor of claim 1, wherein the heat exchanger is one of a plurality of independent heat exchangers enclosed within the containment vessel and vessel head. 5. The molten fuel nuclear reactor of claim 4, wherein each independent heat exchanger in the plurality is provided with an impeller. 6. The molten fuel nuclear reactor of claim 1, wherein the heat exchanger is selected from a shell and tube heat exchanger, a plate heat exchanger, a plate and shell heat exchanger, a printed circuit heat exchanger, and a plate fin heat exchanger. 7. The molten fuel nuclear reactor of claim 6, wherein the heat exchanger is a shell and tube heat exchanger having a plurality of tubes within a shell in which the fluid circulating through the fuel loop passes through the plurality of tubes and a coolant passes through the shell. 8. The molten fuel nuclear reactor of claim 1, wherein the heat exchanger is located below the impeller and above the bottom of the reflector. 9. The molten fuel nuclear reactor of claim 1, wherein the heat exchanger has a coolant inlet opposite the reflector and a coolant outlet opposite the reflector. 10. The molten fuel nuclear reactor of claim 1, wherein the reflector is adjacent to the impeller and separates the reactor core from the impeller. 11. A molten fuel nuclear reactor comprising:a containment vessel and vessel head;a reactor core enclosed within the containment vessel and vessel head, the reactor core having an upper region and a lower region;a heat exchanger enclosed within the containment vessel and vessel head, the heat exchanger fluidly connected to the upper region of the reactor core by an upper channel and fluidly connected to the lower region of the reactor core by a lower channel, the reactor core, heat exchanger and upper and lower channels forming a fuel loop;a reflector defining the lateral extent of the reactor core, the reflector adjacent to the heat exchanger and separating the reactor core from the heat exchanger, wherein the upper channel is above the reflector and the lower channel is below the reflector; andan impeller enclosed within the containment vessel and vessel head, the impeller attached to a shaft that is rotatable by a motor located outside of the containment vessel and vessel head;wherein the impeller is located within the fuel loop such that the impeller, when rotated by the motor, circulates fluid through the fuel loop;wherein the reflector has a top defined by the upper channel and a bottom defined by the lower channel and the impeller is located below the top of the reflector and above the heat exchanger and the heat exchanger is located below the impeller and above the bottom of the reflector. 12. The molten fuel nuclear reactor of claim 11, wherein the shaft penetrates the vessel head and rotatably connects the impeller to a motor located above the vessel head. 13. The molten fuel nuclear reactor of claim 11, wherein the impeller is located in the upper channel. 14. The molten fuel nuclear reactor of claim 11, wherein the heat exchanger is one of a plurality of independent heat exchangers enclosed within the containment vessel and vessel head. 15. The molten fuel nuclear reactor of claim 11, wherein the heat exchanger is selected from a shell and tube heat exchanger, a plate heat exchanger, a plate and shell heat exchanger, a printed circuit heat exchanger, and a plate fin heat exchanger. 16. The molten fuel nuclear reactor of claim 15, wherein the heat exchanger is a shell and tube heat exchanger having a plurality of tubes within a shell in which the fluid circulating through the fuel loop passes through the plurality of tubes and a coolant passes through the shell. 17. The molten fuel nuclear reactor of claim 11, wherein the heat exchanger has a coolant inlet opposite the reflector and a coolant outlet opposite the reflector. 18. The molten fuel nuclear reactor of claim 11, wherein the reflector is adjacent to the impeller and separates the reactor core from the impeller.