Patent Number: 055457975
Section: claims

1. A method of atomic scale fixation and immobilization of plutonium to provide a durable, disposable waste product, said method including the steps of: providing plutonium in the form of one of the group consisting of PuO.sub.2 and Pu(NO.sub.3).sub.4 ;  providing ZrO.sub.2 and SiO.sub.2 ;  mixing said PuO.sub.2 or Pu(NO.sub.3).sub.4, ZrO.sub.2 and SiO.sub.2 together to form a mixture;  cold pressing said mixture to form a pressed product; and  heating said pressed product under pressure to form said durable, disposable waste product in the form of (Zr,Pu)SiO.sub.4. 2. A method according to claim 1, wherein said step of providing plutonium comprises converting plutonium metal to Pu(NO.sub.3).sub.4 in dry form. 3. A method according to claim 1, wherein said step of providing plutonium comprises converting plutonium metal to PuO.sub.2 by oxidation thereof. 4. A method according to claim 1, wherein said mixing step includes adding a neutron poison in the form of Gd.sub.2 O.sub.3 powder. 5. A method according to claim 1, wherein said mixing step includes adding one of the group consisting of a .UPSILON.-emitter, and powdered ZrSiO.sub.4 doped with a .UPSILON.-emitter. 6. A method according to claim 3, wherein said heating step comprises sintering said pressed product at 1150.degree.-1350.degree. C. for 1 to 2 hours at 15-30 MPa. 7. A method according to claim 2, wherein said heating step comprises sintering said pressed product at about 1800.degree. C. 8. A method according to claim 2, which includes the step, prior to said cold pressing step, of calcining said mixture at about 650.degree. C. 9. A method according to claim 1, wherein said mixing step comprises intimately mixing said constituents in a screw blender. 10. A method according to claim 1, wherein said step of cold pressing said mixture comprises pressing said mixture in a bellows. 11. A method according to claim 10, wherein said heating step comprises heating said pressed product under pressure in said bellows.