Precisely-machined, stainless-steel gauges to allow confirmation of both the inner and outer diameters of the highly-enriched uranium (HEU) target rods used in the MAPLE reactor for molybdenum-99 production. The 482 mm long rods each contained 18.5 g of uranium-235 oxide crush-compressed in a thin annulus between two concentric zircaloy tubes. The tubes had an inside diameter of 13.2 mm and an outside diameter of 15.2 mm. The gauges had NO or NO GO indicators stamped on them to indicate acceptable or unacceptable tolerances in the target rod diametric dimensions.