Patent Number: 
Section: claims

1. A nuclear fuel bundle comprising:an upper tie plate;a lower tie plate;at least one full-length fuel rod extending between the upper tie plate and the lower tie plate;at least one partial length fuel rod extending from the lower tie plate towards the upper tie plate;a fuel assembly component mounted on the at least one partial length fuel rod, the fuel assembly component including,a cylindrical device having first and second ends, the first end having a mounting assembly including a locking assembly attaching the cylindrical device to one of the at least one partial length fuel rods; andthe nuclear fuel bundle being in a nuclear reactor,wherein the cylindrical device is one of a hollow tube with solid walls and a solid rod, the hollow tube not including any material in the tube. 2. The nuclear fuel bundle of claim 1, wherein the fuel assembly component is configured to collect in-service material performance data. 3. The nuclear fuel bundle of claim 1, wherein the fuel assembly component is configured to test fuel materials. 4. The fuel assembly component of claim 1, wherein the cylindrical device is a fuel rod tube. 5. The nuclear fuel bundle of claim 4, wherein the fuel rod tube is an unfueled section of fuel rod cladding. 6. The nuclear fuel bundle of claim 1, further including:at least one of an end cap, an endplug, and a partial length fuel rod endplug attached to the second end of the cylindrical device. 7. The nuclear fuel bundle of claim 6, wherein the fuel assembly component is pressurized. 8. The nuclear fuel bundle of claim 1, wherein the fuel assembly component has the same outer diameter as the partial length fuel rod. 9. The nuclear fuel bundle of claim 6, wherein the second end of the cylindrical device is a partial length fuel rod endplug. 10. The nuclear fuel bundle of claim 1, wherein the locking assembly includes a locking spring recess and a locking spring. 11. The nuclear fuel bundle of claim 1, wherein the mounting assembly includes a bayonet female endplug.