Inspection of contaminated hot cell ductwork

Radiation Sterilization Incorporated of Dekalb County, Georgia, has used 137Cs radiation sources for the sterilization of medical instruments and other commercial items. The cesium is in the form of a salt (CsCl) contained in welded Type 316 stainless steel capsules. One of these capsules has leaked allowing the cesium to escape and to contaminate the internals of the sterilization cell, including the cell ventilation duct, which penetrates the thick concrete cell roof. The embedded cell ductwork required decontamination prior to releasing the facility to resume sterilization activities. Due to the small size (20- x 24-in. cross section) and the long duct runs embedded in the cell roof, it was decided to conduct remote visual inspection and preliminary radiation mapping of the ducts to determine the best method of decontamination. An activity was led by Oak Ridge National Laboratory (ORNL) personnel to identify a commercially available remote inspection vehicle and to equip it with the attachments necessary to perform the required inspection. This paper covers these inspection efforts and the evaluation of the results