Americium-241

Small button containing ²⁴¹AmO₂ from a smoke alarm

52,930.6008 keV

7,543.272 keV

0.0595409 MeV

Americium-241 (²⁴¹Am) is an isotope of americium. Like all isotopes of americium, it is radioactive. ²⁴¹Am is the most common isotope of americium. It is the most prevalent isotope of americium in nuclear waste. Americium-241 has a half-life of 432.2 years. It is commonly found in ionization type smoke detectors. It is a potential fuel for long-lifetime radioisotope thermoelectric generators (RTGs). Its common parent nuclides are β⁻ from ²⁴¹Pu, EC from ²⁴¹Cm and α from ²⁴⁵Bk. ²⁴¹Am is fissile and the critical mass of a bare sphere is 57.6-75.6 kilograms and a sphere diameter of 19–21 centimeters. Americium-241 has a specific activity of 3.43 Ci/g (Curies per gram or 117.29 Gigabequerels (GBq) per gram). It is commonly found in the form of americium-241 dioxide (²⁴¹AmO₂). This isotope also has one meta state; ^241mAm, with an exitation energy of 2.2 MeV, and a half-life of 1.23 μs. Its presence in plutonium is determined by the original concentration of plutonium-241 and the sample age. Because of the low penetration of alpha radiation, americium-241 only poses a health risk when ingested or inhaled. Older samples of plutonium containing plutonium-241 contain a buildup of ²⁴¹Am. A chemical removal of americium-241 from reworked plutonium (e.g. during reworking of plutonium pits) may be required in some cases.

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