 INES 2 |
Potential Radiographer Overexposures |
On September 17, 2007, Texas Department of Health notified the Nuclear Regulatory Commission (NRC) that three occupational personnel employed by a radiography licensee may have received radiation dose(s) in excess of the regulatory limits. The event involved a QSA model 943 radiographic device containing a Co-60 sealed source with an activity of approximately 3.5 terabecquerel (TBq) [94 Ci].
On September 14, 2007, at approximately 10:00 pm, two radiographers were conducting radiographic operations and subsequent to placing film for another exposure, noticed that their pocket dosimeters were off-scale, i.e., greater than 2 millisievert (mSv) [200 millirem]. The film was located approximately seven inches from the exposed source behind a six inch thick steel ladle.
According to the initial notification, the radiographers stated that the source guide tube was previously damaged approximately 1.5 feet from device and may have prevented the source from retracting to the shielded position. A third individual successfully returned the source to the shielded position, but may have incurred a dose in excess of 130 mSv (13 rem), a dose in excess of NRC’s annual occupational whole body dose limit of 50 mSv (5 rem). NRC has no information on extremity doses for the three individuals or whole body doses for the two radiographers that were conducting licensed activities.
The three individuals were medically examined and three separate blood samples drawn on September 15-16 for CBC analysis. In addition, on September 17, 2007, blood was provided for cytogenetic analysis. Personal dosimeters were sent for processing and information will be updated accordingly. The workers have been restricted from radiographic activities, were not wearing required alarming rate meters and have not displayed any unusual symptoms.
The State of Texas is conducting a site inspection and will perform a dose estimation based on an event re-creation.
Event date: Fri, 14-09-2007
