U.S. NRC Blog

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EXIT — A Good Sign of Radiation

Maureen Conley
Public Affairs Officer

refresh leafMost people know radioactive energy can be harnessed to provide electricity and even to diagnose and treat certain illnesses. But would it surprise you to learn that radioactive materials also perform an important safety function by lighting emergency EXIT signs?

Look for the EXIT sign the next time you go to work, school, a sporting event, religious service, the movies, or the mall. If the sign glows green or red, chances are it contains a radioactive gas called tritium. The tritium, a radioactive isotope of hydrogen, is sealed into glass tubes lined with a chemical that glows in the dark. Tritium emits low-energy radiation that cannot penetrate paper or clothing and even if inhaled, it leaves the body relatively quickly. As long as the tubes remain sealed, the signs pose no health, safety, or security hazard.

exit3We estimate there are more than 2 million of these signs in use in the United States. To ensure safety in handling and the manufacturing process, we and our Agreement State partners regulate the manufacture and distribution of tritium EXIT signs. Companies have to apply for and receive a license before they can manufacture or distribute one of these signs.

But because the signs are designed to be inherently safe, the NRC does not require any special training before a building can display the signs. Users are responsible for meeting the requirements for handling and disposal of unwanted or damaged signs and for reporting any changes affecting the signs.

exit2Proper handling and disposal is the most important safety requirement for these signs. A damaged sign could contaminate the immediate area and require an expensive cleanup. That is why broken or unwanted signs must be return to a licensed manufacturer, distributer, radioactive waste broker or radioactive waste disposal facility.

Tritium EXIT signs are one of several types of radioactive consumer products that we allow. These products can be produced and sold ONLY if they have a benefit that outweighs any radiation risk. See our earlier blog post for more information on how we regulate these products.

REFRESH is an occasional series where we revisit previous blog posts.

13 responses to “EXIT — A Good Sign of Radiation

  1. Chuck February 21, 2015 at 4:07 pm

    “Proper handling and disposal is the most important safety requirement for these signs. A damaged sign could contaminate the immediate area and require an expensive cleanup. That is why broken or unwanted signs must be return to a licensed manufacturer, distributer, radioactive waste broker or radioactive waste disposal facility.” – I wonder how many times this has been ignored all over the US. It is hard enough to get people to recycle or agree to plastic bag bans I can only imagine how often these signs wind up in the dump. There has to be a better alternative to these types of signs if they are so hazardous they need to use radioactive special facilities for disposal. Much like Troy said “makes me feel safe”.

  2. Rod Adams (@Atomicrod) February 19, 2015 at 8:42 pm

    The regulations regarding tritium exit signs seem quite reasonable. They recognize the value of the devices and the very low risk associated with them, even if there is an accidental release.

    That is quite a contrast with the way that the NRC reacts when there is a release of far smaller quantities of tritium in the form of tritiated water from a nuclear power plant.

    Entergy, for example, spent tens of millions responding to overreactions by both the state and federal regulators for a release of tritiated water in which the total quantity released was about 1/3 of a curie diluted in about 100,000 liters of water.

    Something tells me that the response for the accidental breaking of a tritium exit sign would cost a few hundred dollars at max, otherwise no one would accept the liability associated with installing them.

    Rod Adams

  3. richard123456columbia February 19, 2015 at 9:41 am

    I live in Canada and have sold these signs and there was no requirements in use or disposal.
    Smoke detectors are all so thrown in garbage cans.

    • Moderator February 19, 2015 at 12:51 pm

      You would need a license to legally distribute these signs in the U.S. That license would obligate you to notify purchasers in the U.S. of requirements for proper disposal.

      Maureen Conley

  4. John Heyer, CIH February 18, 2015 at 4:11 pm

    Not sure I agree with the safety of tritium for signs. My understanding is many of these end up in landfills. In a fire, some of the tritium is converted to tritiated water and would result in contamination. Some exit signs contain upwards of 25 curies (740 GBq), that is not a trivial amount. If one breaks indoors, the area should be evacuated and ventilated to clear the H3 gas to safe levels prior to reoccupancy.

    • Moderator February 19, 2015 at 8:11 am

      From the NRC’s backgrounder on exit signs:

      Under NRC regulations, a general licensee using a tritium EXIT sign must:

      NOT remove the labeling or radioactive symbol or abandon the sign;
      properly dispose of an unwanted sign (see below);
      report to the NRC or appropriate Agreement State any lost, stolen or broken sign;
      inform the NRC or Agreement State of changes to the name or address of the general licensee or the person in charge of complying with the regulations;
      NOT give away or sell the sign unless it is to remain in use at its original location; in such a case, the general licensee making the transfer must give the new owner a copy of the regulations and report the transfer to the NRC or Agreement State within 30 days.

      Tritium EXIT signs must NOT be disposed of as normal trash. To dispose of a sign properly, a general licensee must transfer the sign to a specific licensee—such as a manufacturer, distributor, licensed radioactive waste broker or licensed low-level radioactive waste disposal facility. These facilities may charge a fee for disposing of the sign.

      Within 30 days of disposing of a sign, the general licensee must file a report to the NRC or Agreement State. More information about the regulatory requirements for tritium exit signs can be found at 10 CFR Part 31.5.

      Moderator

    • Soontube Exvermonter February 19, 2015 at 9:18 pm

      Tritiated water has a relatively short biological half-life in the human body, on the order of a week or two, so it does not pose a long-term health hazard from a bioaccumulation viewpoint. H3 gas tends to leak readily from structures with even modest ventilation so indoor releases are also not a significant hazard. You’re not talking about a large volume here, so it is unlikely to accumulate in structural spaces where air exchange is limited. Of all the radioactive species in the biosphere, tritium is probably the one to worry least over. I’d be more concerned with radon than anything else, if we’re pushing FUD here.

  5. richard123456columbia February 18, 2015 at 2:48 pm

    Do these signs work when a little smoke is in the air.
    See problems at this site.
    http://www.ccnr.org/tritium_exit_signs.pdf

  6. kayakdiver February 18, 2015 at 12:36 pm

    As technology progresses, if we are smart, we will find less and less reason to use radiation of any sort. Tritium in these signs will still be around in 100 years. But LED lights with a small battery backup can provide better illumination and none of the radiation.

    So lets get smart and outlaw any new tritium signs.

    • Soontube Exvermonter February 18, 2015 at 8:24 pm

      So will the lithium and other toxic products from your LED light. The tritium will be gone after 100 years because it has a radiological half-life. Then it turns into helium and a harmless electron. The toxic materials in your LED lamps don’t have a half-life so they will be around forever. Better ban those before the tritium signs. Let’s get smart and ban LED lights first because they are more dangerous.

    • Rod Adams (@Atomicrod) February 19, 2015 at 4:51 am

      @kayakdiver

      What materials do you propose for the battery backup? How long will the batteries last? What is the environmental risk if they are not properly disposed of? How much electricity will be used over time in order to keep the batteries charged?

      Why would we want to eliminate the use of safe, affordable, inherently reliable, relatively harmless radioactive materials if the choice is more dangerous and less effective?

      Here is the NRC’s mission statement:

      “The NRC licenses and regulates the Nation’s civilian use of radioactive materials to protect public health and safety, promote the common defense and security, and protect the environment.”

      That does not say that their job is to protect us FROM radioactive materials. Their job is to regulate the use of radioactive materials so that those materials can safely serve the needs of the public. When radioactive materials are the safest and best option available, their use should be expanded, not artificially limited.

      The NRC needs to recognize that ultra-low emission nuclear plants should be encouraged, not burdened with externally imposed costs that do not enhance public safety.

      Rod Adams
      Publisher, Atomic Insights

  7. Daniel February 18, 2015 at 12:23 pm

    Tritium also has a neat application for personal use a keyring so that you can locate your keys at night (or anything else that you could attach this keyring to)

    You can get those in Europe and anywhere else in the world. But the NRC deems these applications of radio active material for personal use illegal in the US.

    When it comes to over regulating the trivial, nobody, I mean nobody beats the NRC.

  8. Troy Martel February 18, 2015 at 12:19 pm

    Makes me feel safe.

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