Patent Number: 048620050
Section: abstract

An apparatus for detecting radioactive contamination in hand-held objects, such as tools used to service a nuclear power facility, is disclosed herein. The apparatus generally comprises a radiation detector assembly having a gas-flow proportional detector, and a platform assembly formed from a perforated sheet of rigid material disposed over the topside of the detector for both supporting the hand-holdable objects and uniformly spacing the object from the detector. The radiation detector assembly is contained within a shielding cabinet having an access opening that is offset out of alignment with the top side of the detector for allowing an operator to deposit and withdraw an object onto and off of the platform. The walls of the shielding cabinet include pocket-like mounting assemblies for releasably holding one or more sheets of lead shielding material so that the amount of background radiation-reducing shielding may be advantageously adjusted. The shielding cabinet further includes a pair of cabinet doors on opposite sides of the cabinets which swing down into a horizontal position which is substantially in alignment with the top surface of the detector. The extra access openings provided in the cabinet, along with the shelf-like support afforded by the swung-down cabinet doors allows objects that are longer than the width of the cabinet to be easily drawn over the top surface of the detector and scanned thereby. Finally, the apparatus includes a space gas-flow proportional radiation detector that undergoes a constant purging with counting gas so that it may immediately replace the primary detector in the event of a malfunction, thereby minimizing downtime.