How much uranium is enough to be dangerous?

Whether via a bomb, or exposure or whatever.

The reason I ask is that I’ve recently developed a bit of an interest in chemistry as a hobby, and I was checking one chemical/equipment website geared mainly towards hobbyists and others whose orders are on the small side. I was quite surprised to find that they sell uranium - $39 for 5 grams, or, for larger orders, $219 for 24g.

I had no idea a regular joe could just order up freakin’ uranium from a website! Could this be a potential danger if the wrong people started placing orders?

Critical mass.

Assuming U235, 52kg is the critical mass. At $219 for 24 g, it would cost $474,499.98. I would hope that an order that big would catch someones attention.

As far as radiation, I have no idea.

Nuclear weapon design and materials.

Probably a bad assumption. U238 is much more common, and also not usable for weapons. In fact, that’d probably be depleted uranium they’re selling, which has even less of the dangerous stuff left in than in the natural state (because the dangerous stuff has already been partly extracted to make nukes).

I assumed U235 since someone looking to make a weapon wouldn’t be interested in "tame"stuff.

Found this site with uranium for sale. It is U238. Also saw sites with depleted uranium munitions.

Unrefined uranium will tick off your Geiger counter, but as long as you don’t keep it next to your skin for years on end it shouldn’t be a problem. Lots of people have antique orange Fiestaware. The orange glaze is uranium based and will tick off the counter.

Now if you could get 5 grams of plutonium, you’d be dead within a few months after playing with it for a few minutes. So would everyone else whose path you ran across that day.

That’s actually the site I was referring to.

To my understanding, metallic plutonium (in subcritical quantities) is mainly hazardous due to its toxicity when inhaled or ingested, which pretty much comes down to its nature as a heavy metal, its high reactivity, and the alpha radiation it emits. The alpha radiation emitted by plutonium does not pose a great risk when outside the body, since alpha particles won’t even really penetrate the outer layers of your skin. It’s only when plutonium is present in a critical mass configuration that it generates enough heat and gamma rays to start killing people. So, as far as I know, you’d probably survive handling 5 grams of plutonium, as long as you didn’t do something silly like swallow it, grind it up and inhale it, or somehow figure out a way to make 5 grams of plutonium go critical. :stuck_out_tongue:

Harry K. Daghlian, the scientist who received a fatal radiation exposure in a criticality accident at Los Alamos in 1945, was working closely with and even handling a 6.2kg sphere of plutonium with no ill effects. It was only when Daghlian accidentally dropped a tungsten brick from the experimental neutron reflector assembly he was building onto the sphere, allowing it to go critical, that he suffered the fatal exposure that killed him horribly over the following month.

I’ve bought several radioactive items from United Nuclear, and been very happy. Even the hottest uranium from there, however, is not even a third as hot as my girl Fierra got when she had a technetium scan lately, which spiked my Geiger counter off the scale within 6 feet of her right after the injection.

Those of us who’ve had the privilege of meeting Fierra will of course know that she qualifies as hot even without technetium. :smiley:

I guess I set myself up for that (unintentionally)… :slight_smile:


Alpha-emitting PU-239 (most isotopes of Pu emit either alpha or beta, with 239 being the most common) will kill you from handling it for a few minutes? Really? I’m pretty sure I’ve seen folks handling larger pieces of plutonium than that without serious injury.

Famously, Professor Bernard Cohen offered to go on TV and eat a gram of plutonium if Ralph Nader would eat a gram of caffeine. This was in response to what he saw as scaremongering about the toxicity of plutonium.

Yes, but would Prof. Cohen do it while driving a Corvair?


:confused: That’s about the caffeine in four 12-ounce cups of coffee. Is 1 gram of plutonium taken internally really that safe? Is Cohen lucky Nader didn’t take him up on the deal? Or am I missing something?

According to Wikipedia what Cohen proposed was a gram for gram match, not necessarily one gram. I am guessing that if you swallow a ball of plutonium it will pass intact and absorb most of its own alpha emissions. My gut feeling still tells me that swallowing a 15 gram PuO2 ball is ridiculously unsafe, but might still have a statistically much better long term survival outlook than consuming 15 grams of caffeine in one sitting.

Well, as other posters have explained, plutonium is a heavy metal, thus toxic in its own right. As an alpha-particle emitter, one imagines it would be dangerous if it were actually absorbed throughout the body, irradiating you from the inside out. However, I can imagine a way that Cohen could (maybe) follow through on his promise with minimal risk:

Take small chunks of plutonium, encase them in steel or acid-resistant plastic capsules, and swallow them. If you did it right, the capsules would just pass through your digestive tract, no harm done. Plutonium wouldn’t get absorbed into your system, and the capsule cover would block the alpha particles.


(Of course, the problem would be that machining plutonium is insanely dangerous - you generate plutonium dust, which is Bad News. So getting the pill-sized chunks is left as an exercise for the reader.)

Sure, I’d take that bet, if I could encapsulate the caffeine. :rolleyes:

It’s sort of a ridiculous bet - I’m sure that caffeine is more acutely toxic than Pu, but I’d much rather ingest 1mg of caffeine than 1mg of finely-divided Pu, and I’m sure that Cohen would, also.

If you’ve got the technology to manufacture plutonium, you’ve probably got the technology to be able to machine it safely.