Patent Number: 
Section: claims

1. A method for actively cooling a containment vessel having an interior surface and an exterior surface and fuel salt in a molten fuel salt nuclear reactor comprising:flowing cold primary coolant into the containment vessel via an inlet channel at a first portion of the containment vessel, wherein at the first portion of the containment vessel the interior surface of the containment vessel is a wall of the inlet channel, thereby cooling the exterior surface of the first portion;flowing the cold primary coolant into a heat exchanger within the containment vessel and spaced apart from the interior surface of the containment vessel, the heat exchanger discharging cooled fuel salt;routing discharged cooled fuel salt through a fuel salt discharge channel at a second portion of the containment vessel, wherein at the second portion of the containment vessel the interior surface of the containment vessel is a wall of the fuel salt discharge channel, thereby cooling the exterior surface of the second portion;routing cooled fuel salt from the fuel salt discharge channel adjacent to a neutron reflector, thereby cooling the neutron reflector; andwherein the cooled neutron reflector is adjacent to a third portion of the containment vessel such that cooling the neutron reflector indirectly cools the third portion. 2. The method of claim 1 wherein the flowing the cold primary coolant into the containment vessel further comprises:flowing the cold primary coolant through the inlet channel inside the containment vessel thermally connected to the first portion of the containment vessel. 3. The method of claim 1 wherein the flowing the cold primary coolant into the containment vessel further comprises:flowing the cold primary coolant through the inlet channel inside the containment vessel to a heat exchanger coolant inlet adjacent a heat exchanger cooled fuel salt outlet. 4. The method of claim 1 wherein the fuel salt is a mixture of at least one fissile salt and at least one non-fissile salt. 5. The method of claim 1 wherein the fuel salt includes one or more of the following fissile salts: UF6, UF4, UF3, ThCl4, UBr3, UBr4, PuCl3, UCl4, UCl3, UCl3F, and UCl2F2. 6. The method of claim 1 wherein the fuel salt includes one or more of the following non-fissile salts: NaCl, MgCl2, CaCl2, BaCl2, KCl, SrCl2, VCl3, CrCl3, TiCl4, ZrCl4, ThCl4, AcCl3, NpCl4, AmCl3, LaCl3, CeCl3, PrCl3 and/or NdCl3. 7. The method of claim 1 wherein the fuel salt is a mixture of UCl4, UCl3, and one or both of NaCl and MgCl2. 8. The method of claim 1 wherein flowing the cold primary coolant into the containment vessel further comprises:contacting the cold primary coolant with the interior surface of the containment vessel at the first portion of the containment vessel. 9. The method of claim 1 wherein routing the discharged cooled fuel salt through the fuel salt discharge channel adjacent to the second portion of the containment vessel further comprises:contacting the cooled fuel salt with the interior surface of the containment vessel at the second portion of the containment vessel. 10. The method of claim 1 wherein routing cooled fuel salt through the channel adjacent to the neutron reflector further comprises:contacting the cooled fuel salt with the neutron reflector. 11. The method of claim 10 wherein the neutron reflector contacts the interior surface of the containment vessel at the third portion of the containment vessel. 12. The method of claim 3 further comprising:flowing heated primary coolant discharged from the heat exchanger through an outlet channel interior to the inlet channel. 13. The method of claim 1 wherein at least one side of the fuel salt discharge channel adjacent to a second portion of the containment vessel is formed by the interior surface of the containment vessel. 14. The method of claim 1 wherein the first portion of the containment vessel extends from a top of the containment vessel vertically to the heat exchanger cooled fuel salt outlet. 15. The method of claim 1 wherein the heat exchanger is a shell and tube heat exchanger having a plurality of tubes within a shell and the method further comprises:flowing cold primary coolant into the shell of the shell and tube heat exchanger; andflowing fuel salt through the tubes of the shell and tube heat exchanger. 16. The method of claim 1 wherein the primary coolant is NaCl—MgCl2.