Self-luminous exit signs mark exits and passages toward exits to guide building evacuations, especially from areas where standard lighted exit signs can't be used. They contain sealed tritium and phosphor that emit a constant glow without requiring electricity, batteries, or an external light source. These self-illuminating, tritium exit signs eliminate the need for hardwiring, battery replacement or other maintenance, and testing protocols. They withstand extreme temperatures and washdowns to allow mounting at exit route doors and doorways in dock areas, food processing facilities, chemical plants and other hazardous locations, and areas without electricity. Universal arrow or chevron knockouts in the signs can be set up at the point of installation to indicate the direction of travel to the nearest exit if the path is not immediately apparent. Nuclear exit signs are regulated by the US Nuclear Regulatory Commission (NRC) and require disposal in accordance with NRC regulations at the end of their 10- or 20-year lifecycle.