REFRESH: Do Not Fear Your Smoke Detector – It Could Save Your Life

Maureen Conley
Public Affairs Officer

refresh leafWe sometimes get calls from people worried about radiation from smoke detectors in their homes. There are many reasons why the public need not fear these products.

Ionization chamber smoke detectors contain very small amounts of nuclear material. They might use americium-241, radium-226 or nickel-63. These products detect fires early and can save lives. [We explained how smoke detectors work in greater detail in an earlier blog post.]

The Atomic Energy Commission granted the first license to distribute smoke detectors in 1963. These early models were used mainly in factories, public buildings and warehouses. In 1969, the AEC allowed homeowners to use smoke detectors without the need for a license. Their use in homes expanded in the early 1970s. The NRC took over from the AEC in 1975.

Makers and distributors of smoke detectors must get a license from the NRC. They must show that the smoke detector meets our health, safety and labeling requirements.

smokedetectornewMost smoke detectors sold today use 1 microcurie or less of Am-241. They are very safe. A 2001 study found people living in a home with two of these units receive less than 0.002 millirems of radiation dose each year. That is about the dose from space and the earth that an East Coast resident receives in 12 hours. Denver residents receive that dose in about three hours. These doses are part of what is known as “background radiation.”

The radioactive source in the smoke detector is between two layers of metal and sealed inside the ionization chamber. The seal can only be broken by the deliberate use of force, which obviously we discourage. Still, even then it would result in only a small radiation dose. The foil does not break down over time. In a fire, the source would release less than 0.1 percent of its radioactivity. It’s important to understand that none of the sources used in smoke detectors can make anything else radioactive.

What about disposing of smoke detectors? A 1979 analysis looked at the annual dose from normal use and disposal of Am-241 smoke detectors. The study used actual data and assumptions that would overstate the risk. It allowed the NRC to conclude that 10 million unwanted smoke detectors each year can be safely put in the trash.

The 2001 study looked at doses from misuse. It found that a teacher who removed an americium source from a smoke detector and stored it in the classroom could receive 0.009 millirems per year. If the teacher used the source in classroom demonstrations, handling it for 10 hours each year would give less than a 0.001 mrem dose. A person who swallowed the source would receive a 600 mrem dose while it was passing through the body.

I hope this information allays concerns. Unless you remove and swallow the source, your dose from a smoke detector could not be distinguished from what you get throughout your day. And that smoke detector could save your life.

 REFRESH is an occasional series during which we revisit previous blog posts. This originally ran on June 11, 2013. We are rerunning now in honor of Fire Prevention Week. According to the National Fire Protection Association, the week was established to commemorate the Great Chicago Fire, which killed more than 250 people, left 100,000 homeless, destroyed more than 17,400 structures and burned more than 2,000 acres. This year’s theme is Smoke Alarms Save Lives: Test Yours Every Month.

 

Bringing Fire Protection Into Focus

Daniel Frumkin
Senior Fire Protection Engineer
 

The NRC’s fire protection staff and graphic artists have worked together to create a new introduction to our website’s fire protection pages. The illustrations for the “Prevention,” “Suppression” and “Safe Shutdown” tabs highlight the details in each area of fire protection.

Fire Protection infographic_r11Prevention is a combination of training, NRC inspections and procedures to keep potential fire starters such as welding under control. U.S. reactors have improved their prevention efforts over time. In 1985 they reported 22 significant fires. By the late 1990s, even though more reactors were running, the annual reporting numbers had fallen by more than half. In 2011 U.S. plants reported only six significant fires – less than one fire for every 10 operating reactors.

The next layer of protection involves fighting fires if they occur at or near a reactor. Plants’ fire detection systems are a lot like the smoke detectors in your house. When these detectors go off, however, trained firefighters show up with extinguishers and fire hoses. Many key plant areas also have automatic sprinkler systems. Plants also have plenty of firefighting water available and can get that water onto a fire using onsite staff and equipment or fire engines from nearby communities.

Even with all these measures, U.S. plants must still be able to safely shut down if a fire breaks out. The fire protection approach puts barriers between each reactor’s multiple sets of shutdown equipment, so a fire can’t disable all the equipment at once. The power and control cables are separated to make sure that those systems are available to shut the plant down.

Plants also have alternate control stations if fires disrupt the control room’s ability to manage the situation. The plants have emergency power sources, both installed large diesel generators and portable equipment the NRC required after 9/11. These sources help ensure fires outside the reactor can’t deprive systems of the electricity they need.

Check out the new graphics and fire protection web pages. We hope this information makes the topic easier to understand and gives you a better sense of how layers of protection help ensure nuclear plants remain safe from fires.