Patent Number: 044366779
Section: claims

1. A method of making a pellet from a powder comprising: (A) placing said powder in a heat-shrinkable self-supporting bottle;  (B) sealing said self-supporting bottle;  (C) isostatically pressing said self-supporting bottle at a temperature which causes it to shrink at about the same rate that the powder within it is compressed; and  (D) decomposing said self-supporting bottle and sintering said powder.  (A) preparing a free-flowing fissile powder and a free-flowing fertile powder;  (B) mixing said free-flowing fissile powder with said free-flowing fertile powder;  (C) filling a heat-shrinkable self-supporting bottle with said mixed powders;  (D) sealing said self-supporting bottle;  (E) heating and isostatically pressing said self-supporting bottle so that the bottle shrinks at about the same rate that the powder within it is compressed; and  (F) decomposing said self-supporting bottle and sintering said powder. 2. A method according to claim 1 wherein said powder is a mixture of fissile and fertile nuclear fuel. 3. A method of making a nuclear fuel pellet comprising 4. A method according to claim 1 wherein said powder is fissile nuclear reactor fuel and a fertile core of nuclear reactor fuel is placed in said self-supporting bottle before said powder. 5. A method according to claim 3 wherein said fissile powder is a mixture of .sup.235 UO.sub.2 and PuO.sub.2 and said fertile powder is .sup.238 UO.sub.2. 6. A method according to claim 3 wherein said fissile powder is UO.sub.2 and said fertile powder is ThO.sub.2. 7. A method according to claim 3 wherein said heat-shrinkable self-supporting bottle is made of cross-linked polyethylene. 8. A method according to claim 3 wherein said self-supporting bottle is sealed with a plug which is fused to said self-supporting bottle. 9. A method according to claim 3 wherein said mixed powder is about 20 to about 25% by weight fissile powder and about 75 to about 80% by weight fertile powder. 10. A method according to claim 3 wherein said mixed powder is about 1 to about 5% by weight fissile powder and about 95 to about 99% by weight fertile powder. 11. A method according to claim 3 wherein said powders are mixed only as needed to fill said self-supporting bottle. 12. A method according to claim 3 wherein said self-supporting bottle is heated at about 100.degree. to about 150.degree. C. and pressed at a pressure sufficient to reduce its volume by about 40 to about 60%. 13. A method according to claim 3 wherein said self-supporting bottle is pressed at about 30,000 to about 60,000 psi. 14. A method according to claim 3 wherein said sintering is under conditions sufficient to reduce the volume of said self-supporting bottle by about 40 to about 60%. 15. A method according to claim 3 wherein said sintering is performed under a greater than atmospheric partial pressure of oxygen at a temperature of about 1100.degree. to about 1400.degree. C. which is followed by reduction in hydrogen. 16. A method according to claim 3 including the additional last step of grinding said pellets to a desired tolerance. 17. A method according to claim 3 wherein said free-flowing fertile powder and said free-flowing fissile powder are prepared by the sol-gel technique.