What is the term for fissile uranium that remains on the surface of a fuel pin after manufacturing?

• A. Cladding Defects
• B. Tramp Uranium
• C. Fuel Gas Diffusion
• D. Primary Fission Product Barrier

Answer: (B)

Tramp uranium refers to fissile uranium that remains on the exterior surface of a fuel pin after fabrication. This surface contamination is not part of the intended fuel matrix and can occur during processing, making it important to remove or account for before irradiation. It differs from cladding defects (physical flaws in the cladding), fuel gas diffusion (movement of fission gases within the fuel), and the primary fission product barrier (the cladding acting as the main barrier to fission products). Managing tramp uranium helps prevent unintended local reactivity or handling issues and is addressed through cleaning and surface decontamination during manufacturing.