The State provided the following information via email:
The licensee reported the inability to retract an Ir-192 radiography source (model G-60, serial #OA2910) that contained an activity of 1.45 TBq (39.12 Ci) into a SPEC exposure device (model 150, serial #456). The radiographers had attached the guide tube to a ladder within a tank at the Absolute Energy Ethanol Plant located on the Iowa/Minnesota border. Halfway through a shot, a gust of wind blew the ladder over, which crimped the guide tube such that the source could not be retracted. The radiographers located the source in the guide tube and covered it with sandbags. The crimped guide tube was then reformed using a hammer and the source was successfully retracted. A new guide tube was shipped to the jobsite and the damaged guide tube was destroyed. The two radiographers received exposures of 1.1 and 1 mSv (110 and 100 mrem) from the incident. The licensee submitted a written report to the Iowa Department of Public Health on 6/13/2007, but failed to provide the required 24-hour notification. The State of Minnesota performed an audit of the licensee on 7/12/2007 and it was determined that the incident occurred in Iowa. The root cause of the incident is the failure to properly secure the ladder per company policy. Corrective actions taken by the licensee included terminating the lead radiographer involved and providing additional instruction to all radiographers on the policy to secure ladders used as guide tube stands.
Iowa report number: IA070002