Patent Number: 
Section: claims

1. A multi-segment fuel rod for use in a nuclear reactor, the multi-segment rod comprising:a plurality of rod segments,the rod segments being removably mated to each other in an axial direction,the rod segments being individually cladded, andthe rod segments forming a continuous multi-segment rod having continuous cladding in the axial direction when mated in the axial direction;at least one containment assembly disposed within at least one of the rod segments; andat least one irradiation target sealed within the at least one containment assembly so as to provide double containment for the at least one irradiation target and products formed from the at least one irradiation target when exposed to a neutron flux, the at least one containment assembly housing isotopes, the isotopes only having an atomic number greater than 3 and less than 90. 2. The multi-segment fuel rod of claim 1, wherein at least one of the plurality of rod segments not containing the at least one irradiation target contains nuclear fuel. 3. The multi-segment fuel rod of claim 1, wherein at least one of the plurality of rod segments contains a plurality of the at least one irradiation target. 4. The multi-segment fuel rod of claim 3, further comprising:a plurality of containment assemblies disposed within the at least one of the rod segments, whereinthe plurality of irradiation targets include a first irradiation target and a second irradiation target, the first and the second irradiation targets being different elements from each other and producing different isotopes from each other when irradiated under a neutron flux, andthe first and the second irradiation targets are placed in different containment assemblies of the plurality of containment assemblies. 5. The multi-segment fuel rod of claim 1, whereinthe at least one containment assembly comprises:a first end,a second end, andan end cap configured to attach to at least one of the first and the second end to seal the at least one irradiation target inside of the at least one containment assembly. 6. The multi-segment fuel rod of claim 5, wherein the at least one containment assembly includes exterior indicia indicating the at least one irradiation target contained therein. 7. The multi-segment fuel rod of claim 1, wherein the rod segments are removably mated by at least one of an adaptor plug and receptor, a screw and threaded opening, and a tang and receptor. 8. The multi-segment rod of claim 1, wherein the at least one irradiation target is Cobalt-59 that becomes Cobalt-60 when exposed to neutron flux. 9. A fuel bundle for use in a nuclear reactor, the fuel bundle comprising:an upper tie plate;a lower tie plate;a plurality of rod segments removably attached to and between the upper and the lower tie plate and to each other, each of the rod segments being cladded along its entire length so as to form a continuously cladded multi-segment rod;at least one containment assembly disposed within at least one of the rod segments; andat least one irradiation target sealed within the at least one containment assembly so as to provide double containment for the at least one irradiation target and products formed from the at least one irradiation target when exposed to a neutron flux, the at least one containment assembly housing isotopes, the isotopes only having an atomic number greater than 3 and less than 90. 10. The fuel bundle of claim 9, wherein the multi-segment rod includes a top rod segment removably attached to the upper tie plate, a bottom rod segment removably attached to the lower tie plate, and remaining rod segments attached between the top and bottom rod segments. 11. The fuel bundle of claim 10, wherein the top rod segment is an adaptor subassembly containing no irradiation target and wherein the bottom rod segment is an adaptor subassembly containing no irradiation target.