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Dr. Shark

Thu Dec 09 2010, 01:43AM

Registered Member #75 Joined: Thu Feb 09 2006, 09:30AM
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Posts: 711

I guess the most interesting question here is: would it work?

Let's assume that "An average smoke detector for domestic use contains about about 0.29 micrograms of Am-241 (in the form of americium dioxide), so its activity is around 37,000 Bq (or about 1 ÂµCi)", and that we need to charge the leaves to 100kV to generate the required electrostatic repulsion. The gold leave will probably have a capacitance around 1pF, so from C=Q/V we need a charge of 100nC to bring it up to potential. Let's be generous and assume 10% of the alpha particles generated will be captured by the gold. From the electron charge 1.602e-19, we get that 100nC is about 0.3e12 captured particles, or 3e12 emitted particles.

At 37,000 particles per second this means it would take about 8 Million seconds, which is more than 2000 hours or roughly 100 days.

Somebody point out an error in my calculation, it's really depressing if this would not work!

ubuntupokemoninc

Thu Dec 09 2010, 02:42AM

Banned on 1/22/2011 for repeated rule violations after multiple warnings.
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hehe, americium is in smoke detectors, they wouldn't put something that could harm "saftey" of a country threw nuclear war fare!

Dr. Shark

Thu Dec 09 2010, 02:47AM

Registered Member #75 Joined: Thu Feb 09 2006, 09:30AM
Location: Montana, USA
Posts: 711

Interestingly Am undergoes nuclear fission with a really small critical mass, less than a kg IIRC. There have been proposals to use it in mini reactors to power spaceships and such.

ubuntupokemoninc

Thu Dec 09 2010, 02:49AM

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i heard you could add thorium (found in lamp mantles) to americium, and in 10 years you have neptunium, now we can make a reactor

Steve Conner

Thu Dec 09 2010, 01:00PM

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,2933,292111,00.html

"Police say that Hahn's face was covered with open sores, possibly from constant exposure to radioactive materials."

And, his garden shed was recently named as a Superfund site.

Proud Mary

Thu Dec 09 2010, 08:04PM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
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ubuntupokemoninc wrote ...

i heard you could add thorium (found in lamp mantles) to americium, and in 10 years you have neptunium, now we can make a reactor

Americium-241 decays into neptunium-237 without the help of man or beast. Long after you are dead and gone, the americium in your smoke detector will still be fizzling on. After a century, about 15% of it will have transformed itself into neptunium. After 100 centuries, neptunium will be the main source of smoke alarm radiation detected by future archaeologists as they sift their way down through ancient rubbish pits looking for evidence of Nuclear Man.

Conundrum

Thu Dec 09 2010, 10:51PM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
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interesting, i wonder if Am242 would allow a miniature nuclear UAV to be built? such a device would be ideal for long term monitoring of the near space environment and other applications requiring a long endurance.

-A

Bjørn

Thu Dec 09 2010, 11:22PM

Registered Member #27 Joined: Fri Feb 03 2006, 02:20AM
Location: Hyperborea
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What part of the gamma spectrum would go through 1 mm of aluminium and be stopped by 5 mm? 3 counts per second at 1 mm and not detectable (none in several minutes) at 5 mm using a CCD detector.

Proud Mary

Thu Dec 09 2010, 11:26PM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

Conundrum wrote ...

interesting, i wonder if Am242 would allow a miniature nuclear UAV to be built? such a device would be ideal for long term monitoring of the near space environment and other applications requiring a long endurance.

1291936461 543 FT0 Radioisotope Thermoelectric Generator

Radioisotope Thermoelectric Generators have been used in a number of Russian and American space missions. They are also used extensively round the Russian Arctic coast as power sources for remote flashing buoys, automatic weather stations, and so on.

I have also read that a single gram of radium metal will maintain itself about 1Â°C higher than ambient.

High level nuclear waste dumps produce so much heat that they can burst explosively from their containers if their cooling plants break down, as happened at Kyshtym in the Urals in 1957, causing devastating pollution for hundreds of kilometres downwind, some of which remains to this day.

Dr. Shark

Fri Dec 10 2010, 07:19AM

Registered Member #75 Joined: Thu Feb 09 2006, 09:30AM
Location: Montana, USA
Posts: 711

An RTG is a very different beast, since it just relies on natural decay and the resultant heat. With Americium (but the 242 isotope, not 241 commonly found in smoke detectors) you can get an actual neutron chain reaction going with very small amounts, which produces orders of magnitude more heat that then natural decay would. At least that's what Wikipedia says.

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