Radionuclide facts for kids

A radionuclide is a naturally or artificially produced radioactive isotope of an element. They are often referred to as radioactive isotopes or radioisotopes.

Household smoke detectors

Americium-241 container in a smoke detector.

Americium-241 capsule as found in smoke detector. The circle of darker metal in the center is americium-241; the surrounding casing is aluminium.

Radionuclides are present in many homes as they are used inside the most common household smoke detectors. The radionuclide used is americium-241, which is created by bombarding plutonium with neutrons in a nuclear reactor. It decays by emitting alpha particles and gamma radiation to become neptunium-237. Smoke detectors use a very small quantity of ²⁴¹Am (about 0.29 micrograms per smoke detector) in the form of americium dioxide. ²⁴¹Am is used as it emits alpha particles which ionise the air in the detector's ionization chamber. A small electric voltage is applied to the ionised air which gives rise to a small electric current. In the presence of smoke some of the ions are neutralized, thereby decreasing the current, which activates the detector's alarm.

Images for kids

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  Artificial nuclide americium-241 emitting alpha particles inserted into a cloud chamber for visualisation

See also

In Spanish: Radioisótopo para niños