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Radium watches reactor9/4/2023 ![]() ![]() On JDavid’s boyish experiment shut down a neighborhood of 40,000 residents. It became so irradiated a neighbor claimed to have seen it glow. He had been trying to earn his Boy Scout Atomic Energy merit badgeĮighteen years ago, in a bid for a Boy Scout merit badge, David took to his mother’s potting shed and built a breeder reactor. In a fire, the sources would release less than 0.To this day, David believes the $60,000 cost of cleaning up his experiment was an 'over-reaction' and said the shed never glowed. ![]() The NRC discourages this kind of intentional destruction. The seal can only be broken by the deliberate use of force, such as taking a hammer to the smoke detector. This "foil" is sealed inside the ionization chamber. The source is sandwiched between two layers of metal and rolled thin. The radioactive sources are in a form that does not break down or corrode over time. Am-241 and Ra-226 also emit gamma radiation in an amount so low it cannot be distinguished from natural radiation from space and the earth.These particles only travel a few inches, are easily stopped and only present a health hazard if taken into the body. Am-241 and Ra-226 primarily emit alpha particles.Ni-63 emits beta particles, which can travel a few feet but cannot penetrate a smoke detectors plastic housing.The types of radiation from these sources cannot make anything else radioactive. Some early models used radium-226, and commercial smoke detectors and some residential units used nickel-63. Most smoke detectors use americium-241 as their source. Any smoke entering the chamber would interrupt the current and trigger the alarm.Two electrodes, or charged plates, attract the ions, creating a small but steady current.The free electrons attach to other neutral molecules, becoming negative ions.The particles remove electrons from air molecules, creating positive ions.The particles interact with neutral air molecules flowing through the chamber.A radioactive source "decays," or sheds particles and photons from unstable atoms.Ionization chamber smoke detectors rely on radiation to "ionize" the air inside the chamber. It found that 10 million unwanted smoke detectors each year can be safely put in the trash. The study used data where possible and conservative assumptions that overstate the risk. The teacher would get another 0.001 mrem from handling it for 10 hours each year for classroom demonstrations, and 600 mrem it he or she were to swallow it.Ī 1979 analysis looked at the annual dose from normal use and disposal of Am-241 smoke detectors. It found that a teacher who removed the source from a smoke detector could receive a dose of 0.009 millirems per year from storing it in the classroom. The study also looked at doses from misuse. An East Coast resident receives that dose in about 12 hours, a Denver resident in three. That dose can be compared to the "background radiation" that people receive from space and the earth. A 2001 NRC study found people with two of these units in their homes receive less than 0.002 millirems of radiation dose each year. Most units sold today use one microcurie or less of americium-241. Their use in homes expanded in the early 1970s. ![]() In 1969, the AEC allowed homeowners to use smoke detectors without the need for a license. These early models were used mainly in factories, public buildings and warehouses. The Atomic Energy Commission granted the first license to distribute smoke detectors using radioactive material in 1963. Jaeger's experiment helped pave the way for today’s smoke detector. Frustrated, he lit a cigarette-and the smoke moved the meter on his gadget. Walter Jaeger's device failed to register small amounts of gas. In the late 1930s, a Swiss physicist was working on a sensor for detecting poison gas. From accidental discovery to commercial use To receive one, they must show their products meet the NRC’s health and safety requirements and are properly labeled. Manufacturers and distributors do need an NRC license. They are so safe homeowners can use them without an NRC license. These products use very small amounts of radioactive materials. The NRC allows this "beneficial use" of radioactive material because a smoke detector’s ability to save lives far outweighs any health risk from the radiation. Ionization chamber smoke detectors, the most common type, use radiation to detect smoke. Smoke detectors have saved thousands of lives since they came into use in the 1960s. ![]()
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