[ RadSafe ] Am-241 and its uses.

[Geo>K0FF]

Americium-241, an Alpha (5+ MeV) and Gamma Ray (13.9, 26.3, 59.5 keV) emitter,  does not occur in nature. It was discovered at the University of Chicago during the Manhattan Project in 1944 by Glen Seaborg et. al. ,  producing it by neutron bombardment of Plutonium-239  in a reactor. Naturally Am-241 is a byproduct of nuclear detonations too. Today it is made similarly, by neutron capture in Pu-239 or U-239, in a reactor. Estimates indicate a few kg of Am-241 produced each year, and it only takes 1 gram to make 5000 smoke detectors.

Americium behaves biologically like calcium. 
It is a fissile transuranium element, the critical mass is high at 60 kg.
http://www.fissilematerials.org/ipfm/site_down/ipfmreport06.pdf
However, Am-242 is being studied as a lightweight power source.
http://www.tfot.info/articles.php?itemId=26/64/

Am-241 gives off more Gamma Rays per pound than any other isotope.
http://www.milnet.com/rdw.htm

As an Alpha emitter with a moderate half-life of 432.7 years, the isotope has found many practical uses in consumer and industrial applications, exploiting both its Alpha and Gamma emissions. By far the most widely used instrument using Am-241 is the common ionization smoke detector used in every home and many other buildings.

Some other practical uses include:
  a.. medical diagnostic devices 
  b.. research
  c.. XRF element identifiers: Am-241: cadmium (Cd), tin (Sn), antimony (Sb), barium (Ba), and silver (Ag)  
  d.. fluid-density gauges 
  e.. thickness gauges 
  f.. aircraft fuel gauges 
  g.. distance-sensing devices, all of which utilize its gamma radiation. 

http://www.epa.gov/radiation/radionuclides/americium.htm



http://www.ead.anl.gov/pub/doc/americium.pdf



When mixed with Beryllium metal, an efficient portable neutron source is formed which has many uses.
As a sealed neutron source, Am-241 is a key component of many important industrial and military machines. 

Some of these include:

Soil Moisture Gauges

Paving Density Gauges

Oil Well Logging Tools

Thickness Gauges ( paper, glass, metal foil)

Lead in Paint Detectors



Listmembers are encouraged to send the author any additional applications that they know about.



There is NO exempt Quantity listed in 10 CFR 30.71 Schedule B of the NRC regs, meaning 

that *all* uses are licensed. 











Considering all the critical uses for this material, it is surprising that the U.S. DOE no longer supplies it to industry, leaving the only current source being Russia. My understanding from conversations with Oak Ridge is that all Polonium-210 also comes from Russia. Interesting.

http://www.logwell.com/tech/nuclear/Californium-252.html


George Dowell, "Geo" 
NLNL/ New London Nucleonics Laboratory

GEOelectronics at netscape.com



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