Conveyor apparatus for detecting radioactive material in garments

Abstract

An apparatus for detecting localized concentrations of radioactive particles in garments is disclosed. The apparatus generally comprises a conveyor assembly for receiving, moving and discharging garments which have been processed through a decontaminating wash, and a radiation detector assembly including a gas-flow proportional detector covered by a shielding wall of lead on all faces except for the face opposite the garments being inspected. The radiation detector assembly further includes a height adjustment mechanism for simultaneously supporting both the radiation detector and the shield wall so that the shield wall continues to present the same shielding geometry around the detector regardless of which height the detector is positioned over the conveyor assembly, obviating the need for adjusting the subtraction of background gamma radiation everytime the height of the detector is changed. To render detector capable of determining which specific portion of a particular garment contains one or more radioactive particles, a multi-zone type gas-flow proportional detector is used having a single conductive casing which forms a cathode, and a plurality of fork-shaped anode wires contained therein. Additionally, the housing of the radiation detector assembly supports a hold-down roller for firmly holding garments down on the conveyor assembly as they are moved from the infeed to the outfeed side of the assembly, thereby allowing a conveyor belt of minimal dimensions to be used.