Posted on: 27 March 2012
During work activities, a licensee’s radiographer [Radiographer A] appears to have been overexposed while carrying a guide tube that contained a 2.405 TBq (65 curies) Ir-192 source. Radiographer A was conducting work activities on a platform. When he had completed the series of shots, he signaled to Radiographer B, on the deck below, to crank in the source. Radiographer A surveyed the camera and then disconnected the source guide tube and laid it on the scaffold while he lowered the camera. He then picked up the source guide tube, placed it around his neck, and climbed down the ladder to the deck below. Radiographer A laid down the source guide tube and noticed that Radiographer B was having trouble disconnecting the crank-out device from the camera. Radiographer A observed that the camera was still unlocked. He surveyed the camera and then the source guide tube. Radiographer A reported that it was then that their survey meter indicated the source was in the source guide tube and both of their personal dose rate alarms sounded. Radiographer A picked-up the guide tube using long tongs and the source fell out of the guide tube onto the deck. Preliminary estimates are that the guide tube containing the source was around the radiographer’s neck for approximately 15 seconds and his hands were on the guide tube for approximately 30 seconds. However, the exact source location inside the guide tube is presently unknown. The licensee estimated that the radiographer received a 0.56 Sv (56 rem) dose to the whole body and possibly more than 1 Sv (100 rem) dose to the extremities. The licensee’s consultant conducted the source retrieval. Ongoing actions involve an investigation, reconstruction of the event to refine the dose estimate, expedited processing of the licensee’s dosimetry, and contact with the U.S. Radiation Emergency Assistance Center/Training Site (REAC/TS) to assist with the exposure evaluation.