The following was received from the state of
New Jersey via email:
Siemens has operated a take-back program for smoke detectors containing radiation sources since the 1990s. Most smoke detectors contained Am-241, but Ra-226 sources were also handled. This program has been discontinued and the licensee is now undergoing decommissioning. On October 20, 2022, as part of the license termination process, a consulting Health Physicist was contracted to perform characterization surveys of a waste storage room on site. The storage room was the only room where licensed materials were handled. Here, the licensee would disassemble smoke detectors for ultimate disposal via a licensed radioactive waste broker. The results of the survey indicated that fixed alpha contamination existed across the entire floor surface and on the walls in smaller concentrations. The highest reading observed on the floor was 4,387 cpm [counts per minute]. This equated to 13,282 dpm [disintegrations per minute]/100 centimeters squared with the health physicist's survey instrument. This was the first indication that contamination existed within this facility. This was an unplanned contamination event and possibly involved a quantity of material greater than five times the lowest annual limit on intake specified in Appendix B of 20.1001-20.2401 of 10 CFR Part 20, for Am-241.
Licensee corrective actions: No more smoke detectors are being received by the licensee, so no changes to procedures will occur. Current decontamination work is underway by a licensed radiation contractor. The facility will need to be decontaminated to acceptable levels meeting New Jersey's 15 mrem/year release criteria.
On November 17, 2022, the state performed independent surveys of the room to confirm areas of contamination. The presence of fixed contamination was confirmed and removable contamination was also discovered. The state instructed the licensee to cordon off contaminated areas to prevent entry of personnel. The state will also perform confirmatory surveys after decontamination work is completed.