On Saturday, January 9, 2010, the Radiation Safety Officer (
RSO) of IESCO,
LLC, contacted the
California Office of Emergency Services to report that a Selenium 75 (27.5 Curies) industrial radiography source disconnected from the drive cable during radiography operations at the Chevron, El Segundo Refinery. During the first exposure, the source disconnected from the drive cable. This was discovered during the radiographer's confirmatory survey, as required after the source is cranked back in the shielded position. It was discovered that the source was disconnected near the collimator and when the drive cable was retracted, the source would slide back a couple of inches and the pigtail would be caught at a bend in the guide tube, allowing the source to be partially removed from the collimator. The radiographer placed
lead shielding over the exposed source to minimize radiation exposure. The radiographer then contacted the
RSO. Upon arrival at the site, the
RSO disconnected the guide tube from the exposure device and then assessed the situation. He placed more
lead shielding on the camera until the dose rate at 6 feet was at 20 Mr/hr. He returned the drive cable to the guide tube, reinserted the drive cable into the guide tube and removed the guide tube from the collimator. The
RSO was then able to connect the drive cable to the pigtail and crank it back into the exposure device. The
RSO stated that the reading taken from the Direct Reading Pocket Dosimeter (DRPD) of the radiographer was 9 Mr and the DRPD of the
RSO was 25 Mr.
After inspecting the equipment and interviewing the radiographer and assistant, the RSO concluded that the source disconnect occurred due to dirt on the shutter of the drive cable preventing the cover on the pigtail from closing, preventing a secure connection. The RSO has scheduled a safety meeting to ensure that the radiographers are aware of the issue and instructed how to avoid another incident. Further investigation will be deferred until the 30 day report has been submitted and reviewed.
California Report No: 5010-010910