Patent Number: 048274933
Section: claims

1. A method of making a radiography source of a radioactive material, said method comprising the steps of; providing a plurality of radioactive pellets,  providing an open capsule of a rigid metal having sufficient tensile strength to resist substantial deformation under pressure and selected from a group including elements of the periodic table displaced in density by an amount at least on the order of 2.0 gm/cc from the density of the radioactive pellet material, sufficient to be resolvable by X-ray radiography,  disposing the radioactive pellets in said capsule,  compacting the radioactive pellets to reduce source focal size,  providing a rigid metal plug,  inserting the plug in the open capsule,  and welding the plug to said capsule. 2. A method as set forth in claim 1 wherein the compacting step comprises, providing a ram dimensioned for close tolerance fit in said capsule, and compacting the pellets by inserting the ram into the capsule and applying predetermined pressure to the ram. 3. A method as set forth in claim 2 wherein said predetermined pressure is a direct function of the area of pellets to be compacted. 4. A method as set forth in claim 3 including providing a die and disposing the capsule in the die for subsequent compaction of pellets. 5. A method as set forth in claim 4 wherein the capsule is disposed in the die in a manner to hold the capsule so as to prevent any substantial deformation of the capsule due to pellet compaction. 6. A method as set forth in claim 5 wherein the die is provided as a split die including die halves that are closed to retain the capsule. 7. A method as set forth in claim 1 including constructing said capsule of titanium. 8. A method as set forth in claim 7 including constructing said plug of titanium. 9. A method as set forth in claim 1 including providing at least one insert of the same material as said capsule and disposing the insert in the capsule after compacting the pellets and before inserting the plug. 10. A method as set forth in claim 9 including constructing the capsule, plug and insert all of titanium. 11. A method as set forth in claim 1 including providing a cobalt-60 source and providing a capsule of a tensile strength greater than on the order of 45,000 p.s.i. 12. A radiography source of a radioactive material, said source comprising, a plurality of radioactive pellets, an open capsule of a rigid metal having sufficient tensile strength to resist substantial deformation under pressure and selected from a group including elements of the periodic table displaced in density by an amount at least on the order of 2.0 gm/cc from the density of the radioactive pellet material, sufficient to be resolvable by X-ray radiography, said pellets being disposed in said capsule and compacted therein to reduce the source focal size, and a plug disposed in the open capsule and sealed therewith. 13. A radiography source as set forth in claim 12 wherein said predetermined pressure is a direct function of the cross-sectional area of pellets to be compacted. 14. A radiography source as set forth in claim 12 wherein said capsule is constructed of titanium. 15. A radiography source as set forth in claim 14 wherein said plug is constructed of titanium. 16. A radiography source as set forth in claim 12 including at least one insert of the same material as said capsule, said insert disposed in the capsule. 17. A radiography source as set forth in claim 16 wherein said capsule, plug and insert are all constructed of titanium. 18. A radiography source as set forth in claim 12 wherein said pellets comprise cobalt-60 pellets and said capsule has a tensile strength greater than on the order of 45,000 p.s.i.