The licensee reported that after a thorough search of their facility in Covington,
VA they cannot account for three (3)
tritium exit signs. The licensee had decided to return all of their
tritium exit signs to the manufacturer, SRB Technologies. They were able to return 136 of their 139 signs.
The activity of two of the signs was originally 20 Curies each on October 1990 for one sign and July of 1992 for the other sign. Because of decay the activity of the signs now is estimated to be 7.8 Curies and 8.6 Curies respectively. The activity of the third sign is estimated to be in the same range.
The licensee is not sure when the signs were lost but two were installed above an old door in the facility that was replaced with a new door in a remodel some time ago so they may have ended up in a land fill.
THIS MATERIAL EVENT CONTAINS A "LESS THAN CAT 3" LEVEL OF RADIOACTIVE MATERIAL
Sources that are "Less than IAEA Category 3 sources," are either sources that are very unlikely to cause permanent injury to individuals or contain a very small amount of radioactive material that would not cause any permanent injury. Some of these sources, such as moisture density gauges or thickness gauges that are Category 4, the amount of unshielded radioactive material, if not safely managed or securely protected, could possibly - although it is unlikely - temporarily injure someone who handled it or were otherwise in contact with it, or who were close to it for a period of many weeks.
This source is not amongst those sources or devices identified by the
IAEA Code of Conduct for the Safety & Security of Radioactive Sources to be of concern from a radiological standpoint. Therefore is it being categorized as a less than Category 3 source.