Analysis of Soviet smoke detector plutonium

I don't entirely get it. What is "it" here? The room where you do gamma ray spectroscopy, which should have the least ambient noise (radioactivity), or the bedroom, in which case the radioactivity is probably metaphorical? Or it's intended to be a double entendre?

URSpider942• 9 years ago

This has to be the best amateur science write-up I have seen in years, maybe ever.

lokedhs• 9 years ago

Although the author is a professional nuclear engineer, I do agree with you on the quality of the writing.

URSpider942• 9 years ago

I didn't look at his bio, but I assumed that he must do something in the field in his day job -- it would be really hard to stockpile this much knowledge from scratch, even with the help of the Internet ...

Nonetheless, he did this with the gamma spectrometer in his spare room ...

mmmBacon• 9 years ago

Reminds me of David Hahn, a kid who tried to make a breeder reactor in a garden shed. He massed Americium from smoke detectors in an attempt to make Plutonium.

https://en.m.wikipedia.org/wiki/David_Hahn

InclinedPlane• 9 years ago

Yeah, crazy stuff. Shows what's possible if you have no boundaries. He collected old glow in the dark paint and extracted the radium from it then used beryllium foil to make a neutron source that he used to irradiate thorium from kerosene lamps, producing U-233. Very tiny amounts, but remarkable nonetheless.

seesomesense• 9 years ago

https://en.wikipedia.org/wiki/David_Hahn#Death

petee3• 9 years ago

Probably important to highlight that he was 39 when he died...

I always admired his passion, but puzzled at his stubborn lack of safety precautions.

c0nsumer• 9 years ago

I was unaware that he died. :\ He's sort of a local legedend here in SE Michigan. I wish I'd known about his funeral, the funeral home is a few hundred feet from my house.

gumby• 9 years ago

Hey kids, if you plan to play with Pu, what the author fails to mention is that it is not only radioactive but actually poisonous (chemically) as well.

On the other hand, another little known fact is that you can weld it, which isn't true of all metals.

anfractuosity3• 9 years ago

That's interesting with respect to welding. I just assumed all metals could be welded, do you know the reason why some can't out of interest.

Also is plutonium welded for any application, out of curiosity?

reitanqild• 9 years ago

I just assumed all metals could be welded, do you know the reason why some can't out of interest.

Not a welder but spent some time in farming school and on farms:

IIRC Not even all steel can be welded (i.e. at least not in a practical way using standard tools.)

petee3• 9 years ago

One reason certain metals can't be welded is how their crystalline structure is altered by the process, creating a weak or brittle weld/HAZ (heat affected zone: weaker metal surrounding the weld/filler metal altered by heat)

Some metals also have difficult or impossible cooling rates - welding stainless to carbon steel will make a weak weld that is almost guaranteed to crack while cooling because one metal cools and contracts much faster than the other.

The topic is fairly complex, but there is a good textbook/reference for welders put out by the Lincoln Arc Welding Foundation called "Metals and How To Weld Them" that goes deep on structure and metallurgy, in a readable way.

vixen99• 9 years ago

Unthinking, I'd always gone for Ralph Nader's 'the most toxic substance known to mankind'. http://atomicinsights.com/how-deadly-plutonium/ tells a different story. Point being - 'During the Manhattan Project in 1944 and 1945, 26 men accidentally ingested plutonium in quantities that far exceeded what is now considered to be a lethal dose. Since there has been a consistent interest in the health effects of this brand new substance (first discovered by Glenn Seaborg’s team at the University of California in 1940), these men were closely tracked for medical studies. Forty Years Later As of 1987, more than four decades later, only four of the workers had died and only one death was caused by cancer. The expected number of deaths in a random sample of men the age of those in the group is 10. The expected number of deaths from cancer in a similar group is between two and three.'. On the other hand, better play safe!

dboreham• 9 years ago

Not sure they "discovered". Strictly speaking the Berkeley team first isolated, or produced Pu. Its theoretical existence had been known for a while prior (which is why they were trying to produce it). I mean, it wasn't that they were walking around and picked up and chunk and wondered what they had discovered. The project was entirely for the purpose of producing something every Nuclear Physicist knew must exist. They succeeded in making a small piece, which nobody had done successfully before.

noir-york• 9 years ago

Great science writeup!

The Tsar Bomba described as a "the noble purpose of containing capitalist imperialism" - great quote :)

Reason0772• 9 years ago

Modern smoke detectors seem to have done away with ionization in favour of optical technology, and so no longer contain radioactive materials.

Bad news for mad scientists!

anfractuosity3• 9 years ago

Are you sure about that, I thought ones with Americium were more sensitive? I'm pretty sure you can still get both.

Edit: Seems I'm not right regarding sensitivity, wiki says:

"Ionization detectors are more sensitive to the flaming stage of fires than optical detectors, while optical detectors are more sensitive to fires in the early smouldering stage"

Wow it also says:

"Where an ionizing smoke detector has been the only detector, fires in the early stages have not always been effectively detected."

That's worrying.

Reason0772• 9 years ago

Less sensitivity (or rather, being able to have a higher threshold for sounding the alarm) is actually a good feature for general domestic applications.

You don't really want the thing going off every time someone burns a bit of toast or it just becomes an annoyance, and therefore at risk or being removed or disabled.

jsingleton• 9 years ago

You can get both. I recently bought a twin pack containing one of each. The optical one is marketed as "toast proof" so you can put it near the kitchen and the alpha source one is claimed to be more sensitive.

Radioactive ones are usually cheaper but come with plenty of warnings about not disassembling or ingesting the source. Best to have a mix spread around the home. It's also well worth having a CO alarm if you have non-electric heating/cooking.

Analysis of Soviet smoke detector plutonium

Related Stories