Patent Number: 044302762
Section: claims

1. In a method where a UO.sub.2 powder which is sinterable to at least 97% theoretical density at 1600.degree. C. in H.sub.2 in one hour is produced from an aqueous solution of UO.sub.2 F.sub.2, an improvement which enhances the dimensional stability of a fuel pellet made from UO.sub.2 powder, comprising adding a water soluble dopant forming compound containing an element selected from the group consisting of aluminum, calcium, magnesium, titanium, zirconium, vanadium, niobium, and mixtures thereof, to said solution in an amount such that said UO.sub.2 powder contains about 0.05 to about 1.7 mole% of said dopant. 2. A method according to claim 1 wherein said ammonium diuranate and said dopant forming compound are precipitated by the addition of ammonium hydroxide to said solution of UO.sub.2 F.sub.2. 3. A method according to claim 2 wherein said dopant is a nitrate. 4. A method according to claim 1 wherein said element is selected from the group consisting of titanium, niobium, and a mixture of calcium and titanium. 5. A method according to claim 1 wherein said UO.sub.2 is formed into a fuel pellet by grinding, pressing to about 40 to about 65% theoretical density, and sintering at about 1400.degree. to about 1800.degree. C. for about 1 to about 10 hours. 6. In a method where a UO.sub.2 powder which is sinterable to at least 97% theoretical density at 1600.degree. C. in H.sub.2 in one hour is produced from water into which is added UF.sub.6 gas, an improvement which enhances the dimensional stability of a fuel pellet made from said UO.sub.2 powder, comprising adding a water soluble dopant forming compound containing an element selected from the group consisting of aluminum, calcium, magnesium, titanium, zirconium, vanadium, niobium, and mixtures thereof, to said water in an amount such that said UO.sub.2 powder contains about 0.05 to about 1.7 mole% of said dopant. 7. A method according to claim 6 wherein said dopant is a nitrate. 8. A method according to claim 6 wherein said element is selected from the group consisting of titanium, niobium, and a mixture of calcium and titanium. 9. A method according to claim 6 wherein said UO.sub.2 is formed into a fuel pellet by grinding, pressing to about 40 to about 65% theoretical density and sintering at about 1400.degree. to about 1800.degree. C. for about 1 to about 10 hours. 10. In a method where a UO.sub.2 powder which is sinterable to at least 97% theoretical density at 1600.degree. C. in H.sub.2 in one hour is produced from an aqueous solution of uranyl nitrate, an improvement which enhances the dimensional stability of a fuel pellet made from said UO.sub.2 powder, comprising adding a water soluble dopant forming compound containing an element selected from the group consisting of aluminum, calcium, magnesium, titanium, zirconium, vanadium, niobium, and mixtures thereof, to said solution in an amount such that said UO.sub.2 powder contains about 0.05 to about 1.7 mole% of said dopant. 11. A method according to claim 10 wherein said dopant is a nitrate. 12. A method according to claim 10 wherein said element is selected from the group consisting of titanium, niobium, and a mixture of calcium and titanium. 13. A method according to claim 10 wherein said UO.sub.2 is formed into a fuel pellet by grinding, pressing to about 40 to about 65% theoretical density and sintering at about 1400.degree. to about 1800.degree. C. for about 1 to about 10 hours.