Self-luminous exit signs are low-level radioactive signs designed for use in areas where power is limited or unavailable. Each sign contains tritium gas-filled tubes that remain illuminated for up to 20 years. The tubes are manufactured with high impact material and housed in a sealed case. Since tritium is a very weak beta emitter of radiation, it cannot penetrate the tube or housing and there is no external dose from the signs.
Even so, these signs are regulated by the Nuclear Regulatory Commission (NRC) or Agreement State (states that have received regulatory authority from the NRC) and must be tracked accordingly. The signs must conform to NRC & AECB/CNSC regulations for safety.
Tritium-based signs cannot be disposed of using traditional methods. They must be shipped to an exit sign manufacturer or to a company who maintains a radioactive material license to accept tritium.
Should the case be penetrated or compromised and a tube break, the tritium would disperse rapidly into the atmosphere. The internal effect on a person from all of the tritium in one brand-new sign would be less than that received annually from many naturally-occurring radioactive sources. It would be akin to living at sea level and moving to Denver for a year.
– Aaron Edwards, Account Manager