Patent Number: 056132433
Section: claims

1. A process for stabilization of radionuclides derived from naturally occurring mineral sources, the process comprising the steps of: (i) forming a substantially barium-free composition comprising a radionuclide and sufficient stabilizing component to ensure that when the composition is roasted, a crystalline phase is formed having a structure that binds the radionuclide; and  (ii) roasting the composition under conditions sufficient to form said crystalline phase as a granular solid of surface area 1-100 m.sup.2 /g in which the radionuclide is bound such that there is substantially no solubility of the radionuclide. 2. A process according to claim 1, wherein the stabilizing component is a compound of a lanthanide and/or a compound of phosphorus. 3. A process according to claim 2, wherein the stabilizing component is a compound of a lanthanide and a compound of phosphorus. 4. A process according to claim 2 or claim 3, wherein the radionuclide includes uranium and/or thorium and/or progeny radionuclides in the decay chains of thorium and uranium radioisotopes. 5. A process according to claim 2 or claim 3, wherein the radionuclide includes radium. 6. A process according to claim 1, wherein the stabilizing component is a zirconium compound that is capable of producing a zirconia phase when roasted. 7. A process according to claim 6, wherein the stabilizing component includes an element that promotes the formation of a cubic form of zirconia. 8. A process according to claim 6 or claim 7, wherein the radionuclides include uranium and thorium. 9. A process according to claim 1, wherein the composition comprises an aqueous solution of the radionuclide and the stabilizing component. 10. A process according to claim 9, further comprising the step of evaporating the solution prior to said roasting the composition. 11. A process according to claim 1, wherein roasting is conducted at a pressure no greater than 20 atmospheres. 12. A process according to claim 1, wherein said roasting is spray roasting. 13. A process according to claim 9, wherein said solution undergoes hydrolysis of salts therein to oxides, hydrated oxides, hydroxides or mixtures thereof prior to said roasting.