Patent Number: 046648690
Section: claims

1. A method for simultaneously preparing a mixture of about equal amounts of .sup.211 Rn and .sup.125 Xe, and a second mixture of about equal amounts of .sup.211 At and .sup.123 I with a proton-irradiation procedure followed by a one-step chemical procedure, said method comprising; (a) irradiating a body of material selected from the group consisting of .sup.232 Th and .sup.238 U for about 15 hours with protons that have been accelerated to at least 2 GeV,  (b) promptly dissolving said irradiated body of material in a vessel containing a mixture of hydrochloric acid, nitric acid and hydrofluoric acid,  (c) forcing a stream of helium (He) carrier gas into the vessel at a predetermined flow rate to entrain radionuclides of gaseous .sup.210 Rn, .sup.211 Rn, .sup.123 Xe and .sup.125 Xe and trace amounts of radiohalogens and remove them from said vessel,  (d) passing the stream of helium carrier gas and entrained radionuclides through a silver mesh trap that is maintained at a temperature of about 0.degree. C., thereby to eliminate radiohalogens from said stream of gases,  (e) passing said stream of gases through a second trap that is maintained at a temperature of about -196.degree. C., thereby to entrap .sup.211 Rn and .sup.125 Xe in said second trap,  (f) continuing to pass said carrier gas and any entrained radionuclides through a combination chromatographic separator and detector that is operated to first pass essentially of the .sup.123 Xe and .sup.125 Xe into a first collecting chamber that is maintained at about -196.degree. C., and that is subsequently operated to pass .sup.210 Rn .sup.211 Rn into a second collecting chamber that is maintained at about -196.degree. C.,  (g) allowing the radionuclides in said first and second collecting chamber to decay for about 10 to 15 hours, thereby to produce .sup.123 I from the .sup.123 Xe in said first chamber and to produce .sup.211 At from the .sup.211 Rn in said second chamber,  (h) transferring .sup.125 Xe and the remainder of the .sup.211 Rn from said first collecting chamber into a third collecting chamber that is maintained at about -196.degree. C., and then transferring .sup.211 At from the second collecting chamber, through a trap to remove .sup.210 At, into said first collecting chamber, thereby to leave about equal amounts of .sup.123 I and .sup.211 At in said first chamber, while leaving about equal amounts of .sup.211 Rn and .sup.125 Xe in said third chamber.  (g') transferring substantially pure .sup.211 Rn from the second chamber to the first chamber and allowing further decay of substantially all of the .sup.123 Xe and of some .sup.211 Rn, to .sup.123 I and .sup.211 At, respectively.  (a) irradiating a body of material selected from the group consisting of .sup.232 Th and .sup.238 U for about 15 hours with protons accelerated to at least 2 GeV,  (b) discontinuing irradiation of said body for a period of about 15 hours to permit decay of radionuclides having lives shorter than that period,  (c) disssolving said body in a vessel containing a mixture of hydrochloric acid, nitric acid and trace amounts of hydrofluoric acid,  (d) removing gaseous .sup.211 Rn and .sup.125 Xe from said vessel by forcing a stream of helium carrier gas into the vessel at a flow rate of about 1 to 3 milliliters per minute,  (e) passing the stream of carrier gas and entrained .sup.211 Rn and .sup.125 Xe gases through a silver mesh trap that is maintained at a temperature of about 0.degree. C., thereby to eliminate radio-halogens from the stream of carrier gas and entrained radionuclides,  (f) passing said stream of gases through a second trap that is maintained at a temperature of about -196.degree. C., thereby to entrap the radionuclides in said second trap,  (g) discontinuing the stream of carrier gas through said first trap, and vacuum transferring the .sup.211 Rn and .sup.125 Xe radionuclides from said second trap into a storage vessel that is maintained at about -196.degree. C., thereby to provide about equal amounts of said to radionuclides in said storage vessel. 2. A method as defined in claim 1 wherein said .sup.232 Th is irradiated for about 15 hours with protons accelerated to about 28 GeV. 3. A method as defined in claim 1, except that rather than irradiating .sup.232 Th, said body of irradiated material is .sup.238 U, and said irradiation is continued for about 15 hours with protons accelerated to at least 3 GeV. 4. A method as defined in claim 1 wherein said mixture of acids comprises about ninety percent concentrated hydrochloric acid, about ten percent nitric acid, with a trace amount of hydrofluoric acid therein. 5. A method as defined in claim 2 wherein said radiohalogens that are eliminated from the carrier gas by said first trap comprise .sup.210 At and .sup.211 At. 6. A method as defined in claim 5 wherein said predetermined flow rate of the carrier gas is about 1 to 3 milliliters per minute. 7. A method as defined in claim 5 wherein said second trap contains activated carbon or a silica gel mesh. 8. A method as defined in claim 1, including the following step after step (g), which is effective to eliminate .sup.210 Rn and .sup.210 At from the first collecting chamber; 9. A method for simultaneously preparing about equal amounts of .sup.211 Rn and .sup.125 Xe, using a proton irradiation procedure followed by a one-step chemical procedure, said method comprising; 10. A method as defined in claim 9 wherein said second trap contains activated charcoal that is maintained at about -196.degree. C. 11. A method as defined in claim 9 wherein said second trap contains silica gel mesh. 12. A method as defined in claim 9, except that said body of irradiated material consists of .sup.238 U, rather than of .sup.232 Th, and is irradiated for about 15 hours with protons accelerated to at least 3 GeV. 13. A method as defined in claim 12 wherein said .sup.238 U is irradiated with protons accelerated to about 28.5 GeV.