Zapped:
Back a few years ago, when I was putting up movie theaters, we were also using "nuclear" exit signs. The glow was actually put out by some sort of reaction - had no power source. Someone here can probably shed some more light on what the actual chemical process was for those signs. First time I saw them glowing in the back of the truck it kinda freaked me out a bit...
The Nuclear Exit Signs (or "Self-Luminous" Exit Signs) are typically the "Radioluminescent" types, which use the Radioactive Element "Tritium" inside the sign's tubes.
Some may be, or could have been, "Phosphorescent", which uses the same materials as "Glow-In-The-Dark" stuff does, and may be in conjunction with some type of "Photoluminescent" material - a material which absorbs light, then slowly re emits it.
I am more familiar with the Radioluminescent" types, and more specifically, using Tritium instead of Radium + Copper-Zinc Sulfide Paints.
.........HOW IT WORKS...........
The light is produced by the "Bombardment" of ionizing radiation (beta particles, for example).
When the Tritium decays, it produces light.
The half life of Tritium is something like 12 years, so on average a Nuclear Exit Sign using Tritium will last over 20 years.
*** A little Tritium Trivia ***
Tritium ( symbol =
T or ³H ) is a radioactive isotope of Hydrogen.
Tritium decays into helium-3 in a single reaction, where the original ³H becomes ³He and releases one electron and one antineutrino.
Tritium cannot penetrate human skin, so the only way to absorb it is by inhailation or ingesting it.
Tritium occurs naturally - from cosmic rays interacting with gases in the atmosphere (Nitrogen, for example); and it is produced in Nuclear Reactors.
It is occasionally a direct product of nuclear fission, and is also produced in reactors moderated with "Heavy Water" (Deuterium).
When the deuterium moderator captures a neutron, a small amount of Tritium is produced.
Tritium is also used with Nuclear Weapons, as the "Fission Primary" (kind of like a Nuclear "Booster" or Blasting Cap), to aid in the detonation of a Plutonium or Uranium weapon.
I have only basic knowledge on this subject - and this information was stored away in my archives, from many years past!
Nonetheless, I might do some research on Tritium + Radiolumenescent materials soon, and post more data later.
Scott
p.s. please pardon any spelling errors!
