Patent Number: 
Section: claims

1. A nuclear fission fuel mixture, comprising:at least one naturally fissioning actinide; anda ternary metallic additive comprising:a metal first component as a first percentage of the additive total weight;a metal second component as a second percentage of the additive total weight;a metal third component as a third percentage of the additive total weight, wherein the first percentage, second percentage, and third percentage sum to about one hundred percent;wherein the first percentage, second percentage, and third percentage are selected in a solid phase region of an isothermal ternary phase diagram of the ternary metallic additive taken at a temperature between about 450 Celsius degrees and about 700 Celsius degrees. 2. The nuclear fission fuel mixture of claim 1, wherein the first component is molybdenum, the second component is titanium, and the third component is zirconium. 3. The nuclear fission fuel mixture of claim 2, wherein the ternary metallic additive comprises:molybdenum in a range from about 18 percent to about 55 percent of the additive total weight;titanium in a range from about 38 percent to about 59 percent of the additive total weight; andzirconium in a range from about 2 percent to about 27 percent of the additive total weight. 4. The nuclear fission fuel mixture of claim 2, wherein the ternary metallic additive comprises:molybdenum in a range from about 45 percent to about 55 percent of the additive total weight;titanium in a range from about 38 percent to about 48 percent of the additive total weight; andzirconium in a range from about 2 percent to about 12 percent of the additive total weight. 5. The nuclear fission fuel mixture of claim 2, wherein the ternary metallic additive comprises:molybdenum in a range from about 18 percent to about 28 percent of the additive total weight;titanium in a range from about 48 percent to about 58 percent of the additive total weight; andzirconium in a range from about 17 percent to about 27 percent of the additive total weight. 6. The nuclear fission fuel mixture of claim 2, further comprising niobium, wherein the nuclear fission fuel mixture contains less niobium by weight than any one of molybdenum, titanium, and zirconium. 7. The nuclear fission fuel mixture of claim 1, wherein the naturally fissioning actinide is uranium. 8. The nuclear fission fuel mixture of claim 7, further comprising plutonium. 9. The nuclear fission fuel mixture of claim 1, wherein the first component is molybdenum and the second component is tungsten. 10. The nuclear fission fuel mixture of claim 1, wherein the first component is molybdenum and the second component is tantalum. 11. A nuclear fission fuel mixture for use in a fission reactor in which the nuclear fission fuel mixture remains solid under all anticipated operating conditions, the nuclear fission fuel mixture comprising:at least one naturally fissioning actinide as a first percentage of the total weight of the nuclear fission fuel mixture;molybdenum as a second percentage of the total weight of the nuclear fission fuel mixture; andone or more metals other than molybdenum as a third percentage of the total weight of the nuclear fission fuel mixture,wherein the first percentage, second percentage, and third percentage are selected such that the nuclear fission fuel mixture exhibits a solidus temperature above the likely to exceed the fuel operating temperature of a sodium cooled fast reactor. 12. The nuclear fission fuel mixture of claim 11, wherein the one or more metals comprises at least one of titanium, zirconium, tungsten, tantalum, niobium and palladium. 13. The nuclear fission fuel mixture of claim 11, wherein the at least one naturally fissioning actinide comprises at least one of uranium and plutonium. 14. The nuclear fission fuel mixture of claim 11, wherein the nuclear fission fuel mixture comprises:uranium in a range from about 85 percent to about 99 percent of the total weight of the nuclear fission fuel mixture;molybdenum in a range from about 1 percent to about 13 percent of the total weight of the nuclear fission fuel mixture; andtitanium in a range from about 1 percent to about 4 percent of the total weight of the nuclear fission fuel mixture. 15. The nuclear fission fuel mixture of claim 11, wherein:the first percentage, second percentage, and third percentage sum to about one hundred percent; andthe first percentage is in a range of about 80 percent to about 97 percent of the total weight of the nuclear fission fuel mixture. 16. The nuclear fission fuel mixture of claim 11, wherein:the first percentage, second percentage, and third percentage sum to about one hundred percent;the first percentage, second percentage, and third percentage are selected in a solid phase region of an isothermal ternary phase diagram of the nuclear fission fuel mixture taken at a temperature below the upper temperature limit. 17. The nuclear fission fuel mixture of claim 11, wherein:the first percentage, second percentage, and third percentage are selected in a triangular region of a uranium-molybdenum-titanium ternary diagram having three corners selected from a set of four points consisting of:uranium as about 98 percent and titanium as about 2 percent of the total weight of the nuclear fission fuel mixture;uranium as about 90 percent and molybdenum as about 10 percent of the total weight of the nuclear fission fuel mixture;uranium as about 87 percent, molybdenum as about 11 percent, and titanium as about 2 percent of the total weight of the nuclear fission fuel mixture; anduranium as about 90 percent, molybdenum as about 9 percent, and titanium as about 1 percent of the total weight of the nuclear fission fuel mixture. 18. A method of making nuclear fission fuel, comprising:providing at least one naturally fissioning actinide;providing molybdenum;providing a metal other than molybdenum; andpreparing a total weight of a fuel mixture by mixing the at least one naturally fissioning actinide, the molybdenum, and the metal, the fuel mixture comprising:the at least one naturally fissioning actinide as a first percentage of the total weight;the molybdenum as a second percentage of the total weight; andthe metal as a third percentage of the total weight,wherein the first percentage, second percentage, and third percentage are selected in a body-centered cubic solid phase region of a phase diagram of the fuel mixture. 19. The method of claim 18, wherein:the first percentage, second percentage, and third percentage are selected in a triangular region of a uranium-molybdenum-titanium ternary diagram having three corners selected from a set of four points consisting of:uranium as about 98 percent and titanium as about 2 percent of the total weight of the nuclear fission fuel mixture;uranium as about 90 percent and molybdenum as about 10 percent of the total weight of the nuclear fission fuel mixture;uranium as about 87 percent, molybdenum as about 11 percent, and titanium as about 2 percent of the total weight of the nuclear fission fuel mixture; anduranium as about 90 percent, molybdenum as about 9 percent, and titanium as about 1 percent of the total weight of the nuclear fission fuel mixture. 20. The method of claim 18, wherein the fuel mixture comprises:the at least one naturally fissioning actinide; anda ternary metallic additive comprising:molybdenum in a range from about 18 percent to about 55 percent of the weight of the additive;titanium in a range from about 38 percent to about 59 percent of the weight of the additive; andzirconium in a range from about 2 percent to about 27 percent of the weight of the additive.