Tritium Exit Signs

Tritium exit signs or gaseous tritium source exit signs are sign boards used to indicate an emergency exit. These are very widely used nowadays. They are better compared to other traditional or hard-wired exit signs because they do not require electricity. They work on the principle of radio-luminescence. Earlier, people generally used radium for creating display boards.

Now, use of radium is prohibited in most countries because it increases the chances of bone cancer. These signs are nothing but glass tubes which are filled with this radioactive gas and coated with phosphor internally. Therefore, they are also called gaseous tritium light source or GTLS. The life span of these sign boards depends on the amount of this gas present in the sign tube. On an average, it is about 10 to 20 years.

Tritium is an isotope of hydrogen, whose mass is three times greater than mass of any hydrogen atom. It possesses radioactive characteristics. It is usually in the gaseous form at normal pressure and room temperature. The nucleus of this gas contains one proton and two neutrons. It has a half life of 12.33 years.

As compared to hydrogen atoms, it combines with other light atoms more easily. It forms helium-3 by a radioactive decaying reaction. Although it is a radioactive element, it does not cause any significant health hazard as long as it is not ingested in a very high amount. However, inhalation of gaseous tritium can be dangerous.

Radioactive gaseous tritium is capable of emitting light that is visible to humans. The luminescence is created when a reaction takes place between the emitted electron and phosphor. This gas emits electrons through a process called beta decay. Beta decay is a self-generated process, in which any radioactive, unstable atomic nucleus loses energy by emitting beta particles that are electrons.

It is a low level beta radiation which is not capable of penetrating the skin. Therefore, it does not cause any serious health problems. This whole process of producing a fluorescent light with the help of this gas is called tritium illumination. It is used in all exit signs that contain this gas. The same technology is also used in rifle sights, wrist watches, clocks, and key-chains.

These sign boards do not run on electricity, batteries, or generators. They illuminate even at the time of power failure. Therefore, their usage cost is reduced. There are no chances of explosion, as these are a non-electrical equipment. They are very safe to use.

They require very low maintenance, and no wiring or complex mechanism or procedure is needed for installation. They can be replaced or repositioned without much difficulty. They are a very reliable source of light.

Broken or damaged sign boards need to be disposed immediately because they contain gaseous tritium, which is not safe for human respiration. It is capable of causing cancer if absorbed in the body at a significant level.

Therefore, the disposal of these exit signs must be done immediately. It is mandatory to do the HAZMAT clean-up procedure according to the federal law. The clean-up and disposal procedure is a bit expensive.

These signs are tracked and stipulated by the U.S. Environmental Protection Agency (EPA), Nuclear Regulatory Commission, and Clean Air Act, for safety purposes.

• Vacate the area immediately.
• Open all the doors and windows, which will help in minimizing the concentration of this gas in the air.
• Inform the Nuclear Regulatory Commission and State Radiation Protection Program as soon as possible.

• Strictly follow all the rules and regulations, and dispose the sign board as per the HAZMAT clean-up procedure.
• Check if anyone has been exposed to the gaseous tritium. That person will need to be treated immediately.

If a person inhales it, he should be provided emergency care treatment even before obtaining a regular medical aid. The person should take a shower immediately; and in case he is unconscious, his hands and face should be washed with water.

The person's clothes should be changed and kept in a separate, isolated bag as they may be contaminated as well. The person should drink plenty of fluids, which will help to dissolve the inhaled tritium. This will reduce the risk factors involved due to inhalation of this gas.

However, immediate and cumulative urine samples of the person should be sent to the Nuclear Regulatory Commission for further diagnosis.