Flaw detection and evaluation

Apparatus for inspecting fuel pellets for a nuclear reactor including a roller stand, the said roller stand having rollers providing between them a seat for each of said pellets, and a first drive for rotating said rollers, transfer means for depositing pellets one-by-one on said seat, each deposited pellet being rotated by the rotation of the rollers forming said seat, a light source, optical means cooperative with said source for projecting a light beam on each pellet in said seat, said optical means including a multiple-sided prism and a second drive for rotating said prism to cause said light beam to scan said pellet in said seat, means connected to said first and second drives for synchronizing said drives, pellet sorting means, and means connected to said sorting means, responsive to the resulting light emitted by said pellet in said seat for sorting said pellet in accordance with its properties as manifested by the resulting emitted light.

In apparatus for inspecting fuel pellets for a nuclear reactor for flaws, each of said pellets in its turn being disposed in a pellet seat for inspection;

• an optical system comprising means, including a source of light, for producing a light beam, a prism interposed in said light beam, means connected to said prism for rotating said prism to scan said pellet with said light beam along a direction generally parallel to the axis of said pellet, a first cylindrical lens interposed in said light beam between said source and said prism for converging said beam to a line image generally perpendicular to the axis of said pellet at a point in said light beam just beyond said prism, a second cylindrical lens interposed between said prism and said pellet seat for converging said beam to a line on the surface of said pellet, generally parallel to the axis of said pellet, and a third cylindrical lens interposed between said prism and said pellet for focusing said line image on said surface of said pellet.

The method of inspecting fuel pellets for a nuclear reactor for flaws to determine if the shapes and extents of the totality of the flaws in each pellet exceed a predetermined maximum acceptable shape and extent, the said method including scanning elemental areas of the surface of each pellet with a beam of light, responsive to the resulting light reflected by said pellet, determining the shape and surface dimensions of each flaw in the surface of said pellet to determine for each flaw a flaw quality index, dependent on its shape and said surface dimensions, said surface dimensions being evaluated with each flaw assumed to have the contour and surface of a plane curve on the surface of said pellet, summing the flaw quality indexes from all flaws in the surface of said pellet to derive a surface-quality index, and evaluating said pellet based on its surface-quality index and comparing said surface-quality index with the surface-quality index corresponding to said acceptable shape and extent.