5 ms·
A lot of smoke detectors use the radioactive isotope americium-241 in an ionization process to detect smoke. Get enough smoke detectors, and you can have a goo
by mrbill 13y ago
A lot of smoke detectors use the radioactive isotope americium-241 in an ionization process to detect smoke. Get enough smoke detectors, and you can have a good amount of radioactive material.
Read up on David Hahn, who hit the news in '94 for trying to build a breeder reactor in his back yard using sources scavenged from among other things, smoke detectors.
- TallGuyShort 13y agoWhoa - I actually had no idea. I always assumed it was general electronics because I was instructed to do that for every transaction - even when I was just reselling a bunch of resistors.
- mrbill 13y agoYep. A quick summary: http://www.damninteresting.com/smoke-detectors-and-a-radioactive-boyscout/ http://www.damninteresting.com/smoke-detectors-and-a-radioac...
- cbaleanu 13y agoRadioactive smoke detectors mandatory in houses. Hmm, what's wrong with this picture?
- mindslight 13y agoThe irrational fear that's thrown around whenever the word 'radiation' is used?
- nraynaud 13y agoare you talking about the classification of smoke detectors as weapon material?
- jordanthoms 13y agoSo much this. It's as bad as when someone is trying to demonize some chemical in food, and lists all the other things it's used in, as if that has any relevance to it's safety...
- _delirium 13y agoIt's a pretty small amount of radioactive material, about 1 μCi (roughly equal to 2000 bananas). And in normal usage, you probably shouldn't be removing the insides of the smoke detector and eating it or anything, unlike the tasty bananas. Nonetheless, they're being phased out in a lot of places, mostly due to disposal worries. While one smoke detector is fairly harmless, tens of thousands being dumped in landfills is more of a concern, and properly recycling them is expensive. Optical smoke detectors based on LEDs are now fairly affordable, don't have the disposal issues, and may also perform better.
- capnrefsmmat 13y agoAnd the alpha radiation emitted is barely able to penetrate a sheet of paper, let alone the detector housing and ten feet of air to your body.
- jamesaguilar 13y agoBut then it gets into the water supply and is bombaring your cells from nanometers away . . .
- lgeek 13y agoExcept that americium dioxide is insoluble[0], so it wouldn't dissolve in the water supply. Even if consumed, it would pass straight through your digestive system and wouldn't accumulate in the body. [0] http://media.cns-snc.ca/pdf_doc/ecc/smoke_am241.pdf http://media.cns-snc.ca/pdf_doc/ecc/smoke_am241.pdf
- Tuna-Fish 13y agoNothing, because the smoke detector uses an alpha emitter, and alpha radiation is blocked by practically everything, including a sheet of paper, or roughly 4 cm or air.
- anigbrowl 13y agoThank you. It's depressing how quick people can be to dismiss something as stupid without considering how those rules came about in the first place.
- nraynaud 13y agoAnd so what? some guy stabs someone with a screwdriver and the US regulate the export of them between Commonwealth countries, still without regulating the AK-47 in its own country? There is more regulation on CNC machining center than on firearms. It's stupid. The US doesn't refrain from sending hellfires missiles on weddings, which kills more surely than the once in a lifetime freak who assemble some mildly radioactive stuff in his backyard. If it's for the radiations, I see people playing with X-ray on youtube everywhere, there is 0% chance of chain reaction, nobody cares about chemical contamination in the US, so I don't know why they would freak about a mildly radioactive contamination in a foreign country either. What I begin to see, is an entire world under occupation.
- wbl 13y agoThat's because an AK-47 is an AK-47: it's not a game-changer. But a CNC machining system that lets you build silent ship propellers can dramatically change the threats the world faces.
- nraynaud 13y agoAll the advances in CNC machining systems are published on the internet. And there is some degree of self replicating capability in them (basically you can machine the parts yourself, and fine-tune the design by hand to get a machine of better capability than the previous one).
- marshray 13y ago> But a CNC machining system that lets you build silent ship propellers can dramatically change the threats the world faces. Bullshit. (and yes I know about the Toshiba incident)
- jamesaguilar 13y agoApparently the risk is that someone would use it to create a dirty bomb. It's not dangerous unless ingested or inhaled, and it's not apparently easy to use as any kind of nuclear fuel. I guess this is kinda reasonable.
- lgeek 13y agoA smoke detector contains about 0.25 μg of americium [0], which is painted on the inside of a chamber. In small quantities, it seems americium dioxide can only be dangerous if inhaled [0]. According to David Hahn's Wikipedia page[1], his reactor used thorium, purified from thorium ash used in lantern mantles, and not americium. What's more, smoke detectors go straight to landfills in many places. I think it's unresonable to consider them a realistic threat. [0] http://media.cns-snc.ca/pdf_doc/ecc/smoke_am241.pdf http://media.cns-snc.ca/pdf_doc/ecc/smoke_am241.pdf [1] http://en.wikipedia.org/wiki/David_Hahn#Creation_of_the_reactor http://en.wikipedia.org/wiki/David_Hahn#Creation_of_the_reac...