Patent Number: 
Section: claims

1. A method of producing uranium nitride (UN), the method comprising:reacting a reaction mixture comprising uranium carbide with a gas comprising hydrogen and nitrogen;cooling the reaction mixture to a temperature below a phase transition temperature between a phase comprising UN and a phase comprising U2N3, wherein such temperature ranging from 1352° C. to 1132° C., to thereby produce a phase comprising U2N3; andheating the reaction mixture to a temperature above the phase transition temperature between the phase comprising UN and the phase comprising U2N3, wherein such temperature is greater than 1352° C., to thereby convert the phase comprising U2N3 to the phase comprising UN. 2. The method of claim 1, the method further comprising:reacting UO2 with at least three molar equivalents of carbon to form the reaction mixture comprising uranium carbide. 3. The method of claim 2, wherein the at least three molar equivalents of carbon comprises an excess of three molar equivalents of carbon. 4. The method of claim 2, the method further comprising:granulating the reaction mixture comprising uranium carbide prior to reaction with the gas comprising hydrogen and nitrogen. 5. The method of claim 1, the method further comprising:repeating the cooling the reaction mixture and heating the reaction mixture to purify the UN. 6. The method of claim 2, wherein the reacting UO2 with at least three molar equivalents of carbon is accomplished under an active vacuum. 7. The method of claim 2, wherein the reacting UO2 with at least three molar equivalents of carbon is accomplished under an inert atmosphere comprising N2, Ar, He, H2, or a mixture thereof. 8. The method of claim 1, the method being a continuous process wherein the reaction mixture comprising uranium carbide is continuously moved through a series of at least first, second, and third reaction zones arranged in a sequence, wherein:the first reaction zone has a temperature corresponding to the reacting the reaction mixture comprising uranium carbide with the gas comprising hydrogen and nitrogen;the second reaction zone has a temperature corresponding to the cooling the reaction mixture to the temperature below the phase transition temperature between the phase comprising UN and the phase comprising U2N3, wherein such temperature ranging from 1352° C. to 1132° C., to produce the phase comprising U2N3; andthe third reaction zone has a temperature corresponding to the heating the reaction mixture to the temperature above the phase transition temperature between the phase comprising UN and the phase comprising U2N3, wherein such temperature is greater than 1352° C., suitable to convert the phase comprising U2N3 to the phase comprising UN. 9. The method of claim 1, wherein the heating the reaction mixture to the temperature above the phase transition temperature between the phase comprising UN and the phase comprising U2N3 to convert the phase comprising U2N3 to the phase comprising UN comprises heating the reaction mixture to a temperature of 1375° C. to 2000° C.