The following information was provided by the
South Carolina Department of Environmental Services (the Department) via phone and email:
The licensee submitted a written report on May 30, 2025, indicating that the estimated total effective dose equivalent to an adult member of the public was determined to be 129 mrem/year for calendar year 2023 and 106 mrem/year for calendar year 2024. The licensee later submitted an updated calculation on June 17, 2025, indicating that the estimated total effective dose equivalent to an adult member of the public was determined to be 154 mrem/year for calendar year 2024.
The member of the public was an employee of the licensee, who occupied office space adjacent to a portable gauge storage location. The licensee had an area dosimeter/monitor to monitor the dose in the occupied office space. The annual doses are based on results from the area dosimeter/monitor and calculations to account for distance from the area dosimeter/monitor and time spent in the office.
The devices stored in the portable gauge storage location include four Troxler model 3400 series devices housing 8 millicuries of Cs-137 and 40 millicuries of Am-241/Be, and two Instrotek model 3500 series devices housing 10 millicuries of Cs-137 and 40 millicuries of Am-241/Be.
The discovery of the event was the result of a routine inspection conducted by the Department between February 6, 2025, and March 19, 2025. The Department and the licensee corresponded several times between March 19, 2025, and May 30, 2025, regarding the details of the event. The licensee made a determination on reporting applicability and submitted a written report on May 30, 2025.
The licensee's corrective actions included moving the member of the public to another office away from potential exposure, restricting access to the office space adjacent to a portable gauge storage location, and adding additional shielding to the portable gauge storage location for adjoining offices and hallway.
South Carolina Event Number SC250004