METHOD OF AND APPARATUS FOR INSPECTING FLAWS OF FUEL PELLETS FOR NUCLEAR REACTOR

摘要

This invention concerns a novel technique for quantitatively evaluating the surface qualities of nuclear fuel pellets. Each pellet (P) is subjected to inspection while being rotated on rollers (267, 269). An optical system including a rotating octagonal scanning prism (907) produces a sharp focused light beam and focuses and beam on the surface of the pellet. The light reflected from the pellet surface is focused by lens means (925) on a baffle (927) having a narrow slit. The light passing through the slit is incident upon a photocell (929). Light derived from a flaw in the pellet surface is focused as an image away from the slit and is intercepted by the wall of the baffle. Thus no output is produced by the photocell. Based on the address information generated from a scan address generator (941, 943), a computer calculates the area and perimeter of each flaw scanned by the beam and derives a flaw quality index therefrom. Then, by summing the flaw quality indexes for all flaws on the pellet surface, a surface quality index is derived. Each pellet is evaluated as to flaws based on its surface quality index.