Patent Number: 
Section: claims

1. A target irradiation system for irradiating a radioisotope target in a vessel penetration of a fission reactor having a pressure boundary, comprising:a target elevator assembly including a body portion defining a central bore and an open bottom end, a center tube that is disposed within the central bore of the body portion and defines a central bore, a target basket including a cylindrical sidewall defining a central bore and a bottom flange, the target basket being slidably receivable within the center tube, and a cable drive assembly that is connected to the target basket by a cable, the target elevator assembly being mounted to the vessel penetration of the reactor; anda target passage that is in fluid communication with the target elevator assembly,wherein the target basket is configured to receive the radioisotope target therein via the target passage and be lowered through the vessel penetration into the reactor when irradiating the radioisotope target, the target elevator assembly forms a portion of the pressure boundary of the reactor when in fluid communication with the reactor, the target basket is movable between a first position in which the target basket is disposed within the central bore of the center tube and a second position in which the target basket is disposed within the fission reactor, and the bottom flange of the target basket forms a seal with a bottom of the center tube when the target basket is in the first position. 2. The target irradiation system of claim 1, wherein the fission reactor is a heavy-water moderated fission reactor. 3. The target irradiation system of claim 2, wherein the radioisotope target is comprised of natural molybdenum. 4. The target irradiation system of claim 1, wherein the target elevator assembly is mounted to the vessel penetration so that a portion of the body portion of the target elevator assembly extends downwardly into the vessel penetration. 5. The target irradiation system of claim 1, wherein the cylindrical side wall of the target basket includes a plurality of apertures so that a moderator fluid of the fission reactor may enter the target basket when the target basket is in the second position and disposed in the fission reactor. 6. A target irradiation system for irradiating a radioisotope target in a vessel penetration of a fission reactor including a pressure boundary, comprising:a target elevator assembly including a body portion defining a central bore and an open bottom end, a center tube that is disposed within the central bore of the body portion and defines a central bore having a bottom surface, a target basket including a cylindrical sidewall and a bottom flange, the target basket being movable between a first position in which the cylindrical sidewall of the target basket is disposed within the central bore of the center tube and a second position in which the target basket is disposed within the fission reactor; anda target passage that is in fluid communication with the target elevator assembly,wherein the target basket is configured to receive the radioisotope target therein via the target passage and be lowered through the vessel penetration into the reactor when irradiating the radioisotope target, and the bottom flange of the target basket forms a seal with the bottom surface of the center tube when the target basket is in the first position. 7. The target irradiation system of claim 6, further comprising a cable drive assembly that is connected to the target basked by a cable. 8. The target irradiation system of claim 6, wherein the target elevator assembly forms a portion of the pressure boundary of the reactor when in fluid communication with the reactor. 9. The target irradiation system of claim 6, wherein the fission reactor is a heavy-water moderated fission reactor. 10. The target irradiation system of claim 9, wherein the radioisotope target is comprised of natural molybdenum. 11. The target irradiation system of claim 6, wherein the target elevator assembly is mounted to the vessel penetration so that a portion of the body portion of the target elevator assembly extends downwardly into the vessel penetration. 12. The target irradiation system of claim 6, wherein the cylindrical side wall of the target basket includes a plurality of apertures so that a moderator fluid of the fission reactor enters the target basket when the target basket is disposed in the fission reactor.