Patent Number: 
Section: claims

1. A multi-segment rod, comprising:a plurality of rod segments configured to be in a nuclear reactor, the rod segments removably mated to each other via mating structures in an axial direction;an irradiation target disposed within at least one of the rod segments; andat least a first portion of at least one mating structure including one and/or more combinations of neutron absorbing materials configured to reduce a power increase that would otherwise occur at the first portion of the at least one mating structure during an operational use of the nuclear reactor. 2. The rod of claim 1, wherein the one and/or more combinations of neutron absorbing materials is not nuclear fuel. 3. The rod of claim 1, wherein the one and/or more combinations of neutron absorbing materials includes a same material as the irradiation target. 4. The rod of claim 1, wherein the one and/or more combinations of neutron absorbing materials does not include a same material as the irradiation target. 5. The rod of claim 1, wherein the one and/or more combinations of neutron absorbing materials has a neutron absorption rate that is about equal to a neutron absorption rate of the irradiation target. 6. The rod of claim 1, wherein the one and/or more combinations of neutron absorbing materials has an atomic weight greater than 3. 7. The rod of claim 1, wherein the plurality of rod segments at least includes a first rod segment removably mated to a second rod segment, the first rod segment having a male connection member, and the second rod segment having a female connection member receiving the male connection member. 8. The rod of claim 7, wherein the male connection member of the first rod segment includes the one and/or more combinations of neutron absorbing materials. 9. The rod of claim 8, wherein a portion of the female connection member includes the one and/or more combinations of the same and/or a different neutron absorbing material as the male connection member. 10. The rod of claim 7, wherein the female connection member of the second rod segment includes the one and/or more combinations of neutron absorbing materials. 11. The rod of claim 10, wherein a portion of the male connection member includes the one and/or more combinations of the same and/or a different neutron absorbing material as the female connection member. 12. The rod of claim 1, wherein the plurality of rod segments at least includes a first rod segment removably mated to a second rod segment, the first rod segment having a first male connection member, the second rod segment having a second male connection member, and a sleeve member having a first female connection member and a second female connection member, the first female connection member receiving the first male connection member and the second female connection member receiving the second male connection member. 13. The rod of claim 12, wherein at least one of the first and second male connection members includes the one and/or more combinations of neutron absorbing materials. 14. The rod of claim 13, wherein at least one of the first and second male connection members includes separate portions including the one and/or more combinations of the same and/or a different neutron absorbing material. 15. The rod of claim 12, wherein the sleeve member includes the one and/or more combinations of neutron absorbing materials. 16. The rod of claim 15, wherein a portion of at least one of the first and second male connection members includes the one and/or more combinations of the same and/or a different neutron absorbing material as the female connection member. 17. The rod of claim 1, wherein the rod segments are individually cladded, the rod segments form a continuous multi-segment rod having continuous cladding in the axial direction when so mated in the axial direction. 18. The rod of claim 1, wherein the irradiation target is not nuclear fuel. 19. The rod of claim 1, whereinat least one rod segment contains at least one container assembly, the container assembly including,a first end,a second end,the irradiation target, andan end cap configured to attach to at least one of the first and the second end to seal the irradiation target inside of the container assembly. 20. The rod of claim 1, wherein the irradiation target includes one of Cobalt Co-59, Molybdenum-99, Chromium-50, Copper-63, Dysprosium-164, Erbium-168, Holmium-165, Iodide-130, Iridium-191, Iron-58, Lutetium-176, Palladium-102, Phosphorus-31, Posassium-41, Rhenium-185, Samarium-152, Selenium-74, Sodium-23, Strontium-88, Ytterbium-168, Ytterbium-176, Yttrium-89, and Xenon-132. 21. A fuel bundle for use in a nuclear reactor, the fuel bundle comprising:a plurality of rods, at least one of the rods being a multi-segment rod, each multi-segment rod including,a plurality of rod segments, the rod segments removably mated to each other via mating structures in an axial direction;an irradiation target disposed within at least one of the rod segments; andat least a first portion of at least one mating structure including one and/or more combinations of neutron absorbing materials configured to reduce a power increase that would otherwise occur at the first portion of the at least one mating structure during an operational use of the nuclear reactor; anda plurality of spacers, each spacer being spaced apart from other spacers in the axial direction, each spacer directly contacting only one of the mating structures along the axial length of the multi-segment rod. 22. The rod of claim 1, wherein the one and/or more combinations of neutron absorbing materials has a different neutron absorption rate than a second portion of the at least one mating structure and the plurality of rod segments, the second portion of the at least one mating structure not being the at least a first portion of the at least one mating structure. 23. The rod of claim 6, wherein the one and/or more combinations of neutron absorbing materials has an atomic weight of less than 90. 24. The rod of claim 1, wherein the one and/or more combinations of neutron absorbing materials includes one or more of Cobalt Co-59, Molybdenum-99, Chromium-50, Copper-63, Dysprosium-164, Erbium-168, Holmium-165, Iodide-130, Iridium-191, Iron-58, Lutetium-176, Palladium-102, Phosphorus-31, Posassium-41, Rhenium-185, Samarium-152, Selenium-74, Sodium-23, Strontium-88, Ytterbium-168, Ytterbium-176, Yttrium-89, and Xenon-132. 25. The rod of claim 1, wherein the one and/or more combinations of neutron absorbing materials is a different material from the irradiation target. 26. The rod of claim 1, wherein the one and/or more combinations of neutron absorbing materials has a higher neutron absorption rate than a second portion of the at least one mating structure and the plurality of rod segments, the second portion of the at least one mating structure not being the at least a first portion of the at least one mating structure. 27. The fuel bundle of claim 21, wherein the one and/or more combinations of neutron absorbing materials includes one or more of Cobalt Co-59, Molybdenum-99, Chromium-50, Copper-63, Dysprosium-164, Erbium-168, Holmium-165, Iodide-130, Iridium-191, Iron-58, Lutetium-176, Palladium-102, Phosphorus-31, Posassium-41, Rhenium-185, Samarium-152, Selenium-74, Sodium-23, Strontium-88, Ytterbium-168, Ytterbium-176, Yttrium-89, and Xenon-132. 28. The fuel bundle of claim 21, wherein the one and/or more combinations of neutron absorbing materials has a higher neutron absorption rate than a second portion of the at least one mating structure and the plurality of rod segments, the second portion of the at least one mating structure not being the at least a first portion of the at least one mating structure.