Most people know that 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.
NRC estimates there are more than 2 million of these signs in use in the United States. To ensure safety in handling and the manufacturing process, NRC and its 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, 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.
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.
Tritium EXIT signs are one of several types of radioactive consumer products that NRC allows. 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.Maureen Conley Public Affairs Officer
13 thoughts on “EXIT — A Good Sign of Radiation”
The definition of response to radiation therapy varies, making comparisons between study results challenging.
I completely agree. It has become so sort of fashion. The dangerous of participating in such activities in very very dangerous and could end up in them people getting skin cancer and worse.
There is natural radiation – God made – for the benefit of all creation and life. Such as sunlight which is readily absorbed and converted into a variety of good stuff for our all wellbeing by nature, plants and animals alike (except some humans who use sun-block). There is artificial, technical man made radiation and emissions often out of control and often invented without knowledge of future long tiime effects on human life or animal life.
Nature including animals have adapted to a full dose or natural radiation including plain tropical sun light – while others hide from sun light and are scared of God made sunlight. May be it often is more our attitude toward an energy rather than the energy itself that creates the hazards. Hundreds of millions of humans live in tropical latitudes, work in fields at noon hours and yet few of them if at all suffer from skin cancer.
Millions are exposed to artificial radiation and chemical hazards and suffer from all kinds of diseases. May be there is a difference between natural radiation and artificial man made radiation.
As far as the tritium signs. The problem is they are ubiquitous and most people do not realize they have a regulated substance inside of them. So the signs do not always get handled as they should. There are more modern options that could replace the tritium signs. They probably should be phased out, It is just an unnecessary regulatory hassle.
What is far more interesting than the signs is this bizarre trolling by a group of nuclear industry bloggers on anything the NRC posts. Would it be appropriate for Pfizer to be disrupting FDA public communications? Probably not. The public has a right to ask questions or communicate with government agencies. It should not be under constant disruption or intimidation by people who are well known to be in the employ of the industry that the NRC regulates. Even worse when I see these nuclear industry employees posting technically inaccurate information in the comments. That seems to be running counter to what the NRC seems to be trying to do with some of these posts to educate the public.
The radiation you receive by laying out and exposing to sunlight does indeed not only include a non-zero number of gamma x-rays, but also is identified as one of the major long term cause of cancers in the US.
The notion of relative risk is essential and should be better outlined by the NRC.
Maybe physicians should be enrolled to ensure the message is perfectly correct wrt the current state of medical knowledges.
Ummm….when some out of control car runs into one of these signs and the debris is scattered some of you proponents better be first on the list to clean it up. Please do it right and don’t just bury it in some child’s sandbox. The dangers are real.
Some numbers would be informative. They might help people understand more about the exceedingly low hazard of tritium, despite all publicity to the contrary in an attempt to make nuclear plant operators look bad.
A typical exit sign might contain 7 curies of H3 (tritium is just hydrogen with two extra neutrons). Though Arnie Gundersen loudly criticized Vermont Yankee for leaking tritium to the environment from their off gas system, the TOTAL quantity of tritium that entered the ground underneath the plant was approximately 0.35 curies and that material was diluted in 138,000 liters of water.
I wrote a blog post for Atomic Insights that showed the math to support that statement. You can find it with a search; the title of the post is “How much tritium leaked from Vermont Yankee before the leak was stopped?”
In other words, a typical tritium sign contains about 20 times as much radioactive material as was leaked into the environment from a very well-publicized, slow leak from a licensed nuclear power plant.
It would be wonderful if the NRC communications branch would provide these kinds of numbers to enable the public to understand the relative risks of something that is routinely accepted versus something that is blown way out of proportion for nefarious reasons.
Instead, the NRC’s reaction was to have the Chairman sit down with people like Gundersen to show how concerned the NRC was about the very minor leaks. Not only that, but the NRC forced the plant owners to engage in time consuming and expensive remediation efforts that cost several millions of dollars that could have been spent for far more productive purposes other than digging up and moving what was essentially clean dirt.
But..but..its RADIOACTIVE. Everything I see on the news or the internet says that’s bad. But maybe I’m wrong to listen to all the gloom and doom from a bunch of fanatics or talking heads , maybe Helen caldicott is wrong when she says there is no safe dose since we are all living on a radioactive world . Maybe I should look at this with a clear and rational mind set and realize that there is risk all around us and this one is acceptable. Pros and cons come with everything. Normal people weigh them then make the greater good decision. Others will never see past their fears or biases and let them rule their decisions.
Isn’t tritium also a naturally occurring element ? Insidious use ? That seems a little over the top, are you also against the peaceful use of dangerous chemicals like teflon in pans or mercury in compact flourescent lights ? Should we ban everything that has any potential for harm or simply understand that the benefits outweigh the potential risks.
What’s more insidious is when people knowingly lay out and radiate their bodies with God’s natural sunlight. What’s even more insidious is when people pay to lay under the canopy of a tanning booth for the same reason. It is preposterous to think that mankind will ever avoid the hazards of life.
This is an excellent example of the benefits we can realize from use of radioactive materials. The gains in safety by having assured emergency lighting are definitely worthwhile. The effect of accidental breakages are negligible, overstated here by the NRC, since tritium is an isotope of hydrogen and released hydrogen will rapidly disperse naturally, posing no threat to anyone. Probably broken glass would be the biggest true hazard.
“Insidious”? PLEASE! I can show you high class pottery shops here in NYC that hawk artsy pieces glossed with uranium oxide paint. You can have lots of fun hearing your geiger counters tick away in Grand Central Terminal and Empire State Building’s lobby here thanks to their beautiful radioactive granite walls and not one radiation warning sign in the place, and that doesn’t even include thousands of as built structures here or rocky vistas out west. You’re apparently also clueless of the near bunny-suit hassle the maintenance crews at my city workplace have to go through to clean up and dispose of damaged mercury lamps under EPA rules, and you’re squawking over a “hazard” which isn’t that much beyond wearing a radium dial watch which fanatically low rad tolerance Japanese airports will senselessly stop you if they detect you wearing one! Get a grip! Radioactivity isn’t any-touch-lethal evil poison out to get us — it’s been PART of our environment for eons and our biology has long adjusted to that. Worry more about the soot and airborne pollutants tearing down your lung cells every day more instead of going on a radiation witch hunt for imperceptible blue-moon exposures barely beyond background (and we can easily live through FAR FAR more than that!), as the local realm around even Fukushima is revealing so by respectable authorities.
This is one of the most insidious uses of radiation in the environment. Since it’s impossible for the NRC to keep track of two million tritium-laced exit signs, each one a radiological hazard, it has been decided that the users will all take care of them properly themselves. This sort of preposterous thinking is typical for the NRC. Notice that no mention of the actual quantities of tritium involved and its potential for danger appears in this blog, other than an admission that a broken tritium exit sign would be a significant (described as “expensive” but it much worse than merely being expensive!) environmental clean-up problem. I’ve already written extensively about tritium, here’s one URL: http://goo.gl/KfcUs
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