Description
Americium-241 ( 241
Am
, Am-241 ) is an isotope of americium. Like all isotopes of americium,
it is radioactive, with a half-life of 432.2 years. 241
Am
is the most common isotope of americium as well as the most prevalent isotope
of americium in nuclear waste. It is commonly found in ionization type smoke
detectors and is a potential fuel for long-lifetime radioisotope
thermoelectric generators (RTGs). Its common parent nuclides are β− from 241
Pu
, EC from 241
Cm
, and α from 245
Bk
. 241
Am
is fissile and the critical mass of a bare sphere is 57.6–75.6 kilograms
(127.0–166.7 lb) and a sphere diameter of 19–21 centimetres (7.5–8.3 in).
Americium-241 has a specific activity of 3.43 Ci/g (126.91 GBq/g). It is
commonly found in the form of americium-241 dioxide (241
Am
O
2). This isotope also has one meta state, 241m
Am
, with an excitation energy of 2.2 MeV (0.35 pJ) and a half-life of 1.23 μs.
The presence of americium-241 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 241
Pu
contain a buildup of 241
Am
. A chemical removal of americium-241 from reworked plutonium (e.g. during
reworking of plutonium pits) may be required in some cases.
