PELLET INSPECTION APPARATUS

摘要

Apparatus for inspecting nuclear fuel pellets in a sealed container for diameter, flaws, length and weight. The apparatus includes, in an array, a pellet pick-up station, four pellet inspection stations and a pellet sorting station. The pellets are delivered one at a time to the pick-up station by a vibrating bowl through a vibrating linear conveyor. Grippers each associated with a successive pair of the stations are reciprocable together to pick up a pellet at the upstream station of each pair and to deposit the pellet at the corresponding downstream station. The gripper jaws are opened selectively depending on the state of the pellets at the stations and the particular cycle in which the apparatus is operating. Inspection for diameter, flaws and length is effected in each case by a laser beam projected on the pellets by a precise optical system while each pellet is rotated by rollers. Each laser and its optical system are mounted in a container which is free standing on a precise surface and is provided with locating buttons which engage locating holes in the surface so that each laser and its optical system is precisely set. The roller stands are likewise free standing and are similarly precisely positioned. The diameter optical system projects a thin beam of light which scans across the top of each pellet and is projected on a diode array. The flaw optical system projects a thin beam of light which scans across the pellet. Unflawed areas of the surface reflects the light to a photodiode; flawed areas diffuse the light and reflect the image of the light spot in the flaw away from the photodiode. The scanning of each pellet is coordinated by a grating and photodiode which produces pulses corresponding to the scanning. The length optical system projects a sheet of light across the length of the pellet producing a shadow which is projected on a diode array.