Oops, I carried a piece of uranium ore in my pocket once when I was a kid.

Factual Questions
1

When I was about 12 (1970), I had a small piece of uranium
ore that came with one of those sets of minerals they sell for kids, that have different types of minerals glued onto
a big card that describes them. On that day I took it to
a science museum and held it up to a Geiger counter that
they had on display, with headphones. The headphones literally screamed when the rock was held near the receptor.

Question is, if I carried a few grams of Uranium ore in my
pocket for a few hours, could I have exposed myself to
dangerous amounts of radiation poisoning? If I understand
radioactive ores, the metal they yield is almost entirely made up of more stable isotopes of uranium and thorium, and
that for bombs or nuclear power these metals must be refined
to isolate the more radioactive isotopes.

So what do you think? If I have a kid will he come out with
two heads? Will I one day get testicular cancer?

2

I grew up in western Colorado, source of much of the country’s uranium. (Matter of fact, my dad worked for the Atomic Energy Commision as a geologist.)

After the ore was processed at the mines, there was lots of tailings left over; i.e., dirt that was surrounding the uranium. Someone had the wise idea of giving these tailings away as fill dirt. Well, because of the boom created by the uranium industry, there happened to be a lot of building going on in my hometown. So a lot of these tailings were used as fill for foundations for schools, churches, and other public buildings. In fact, the elementary school and Methodist church I attended both had tailings.

Years later, they realized their mistake and had to dig out all the tailings and replace it with non-radioactive fill. Besides public buildings, some homes were built on the stuff too. So teams went out to all the homes built in that era to test them.

When they came to my house, my dad escorted them around. Everything was going fine, until they rounded the corner where my bedroom was. The Geiger counter started clicking more. But why such an isolated spot? A natural source wouldn’t be so localized, and an artificial source (assumedly tailings) would be spread out more too.

Then my dad had a thought. He went inside and to my room. Spying a large mound of junk by my bed, he shoved it aside and found my mom’s gem and mineral collection chest. (Yes, my family has rocks in their heads.) Looking through it, lo and behold, he found a uranium ore sample, about the size you described, javaman. He took it outside and showed it to the team. Yep, it made the detector click faster, and when removed from my room, no longer made that corner of the house “hot”.

So: 1) my church was built on radioactive tailings; 2) my elementary school was built on radioactive tailings; 3) I slept next to a uranium sample for 18 years! But now, look at the link in my signature and tell me that my daughter is a mutant (not the Jack O’ Lantern picture). OK, she’s impossibly cuter than any child of mine should be, but I attribute that to my wife’s genes.

3

You mean your duaghter doesn’t really glow in the dark?
Darn… That was my favourite pic.

4

I met up once with a retired schoolteacher who was into mineral collecting. He had all sorts of neat tales of his adventures (he prospected in the South Australia/New South Wales outback, for the most part).

This retired schoolteacher knew a bunch of guys absolutely obsessed with collecting rare specimens from some of the more famous mines in the area; one of these guys was into uranium and radium ore samples. This fellow would carry his most prized (and highly radioactive) specimens in his pockets at all times, because he was afraid someone might take them. Because of the stuff he was carrying, he had no trouble making Geiger counters go nuts.

The guy lived until the age of 94.

(Wonder if they buried him in a lead-lined coffin. :wink: )

5

Nope. For one thing, [sup]238[/sup]U has a really long half-life (>4 billion years), which means it decays slowly, i.e. it’s not terribly radioactive (compared to, say, radium). Second, Uranium and its daughter products decay primarily by alpha emmision. The alpha particles would not penetrate your pocket lining; the dead skin cells on the outside of your body are generally sufficient to protect against external alpha radiation.

For carrying around a few grams of Uranium ore in your pocket for a few hours, I’d estimate you received a dose of maybe a few mR, mostly from the gamma decay of the U daughter products. On average, you get about 1 mR per day from natural background radiation, so a few extra amount to basically nothing in the grand scheme of things.

6

Given the experiences of others who have already posted I’d say you’re in the clear javaman.

Some things to consider–

  1. I have seen people handling refined globes (abouth the size of a softball) of radioactive material with their bare hands. Unfortunately I don’t know if it was Uranium (235, 238?) or Plutonium. Of course, that could be a HUGE difference for all I know (from harmless to lethal). All I mean to point out with this is that some radioactive products can be safe to handle. The person handling the globe said it was slightly warm to the touch due to radioactivity.

  2. Uranium miners seem to manage. There is strong evidence that they suffer from a higher rate of lung cancer and some suggestive (but not conclusive) evidence that their children are at higher risk for leukemia. The cancer bit may be explained by any miner (breathing all the dust and what not). However, I don’t know if Uranium miners actually have it worse than, say, coal miners. In the end, however, these guys are around uranium a good deal more than described in the OP so again you’re probably safe with your little rock.

  3. Ingestion is usually the quick way to hurt yourself with radioactive materials. Plutonium, IIRC, is one of the most toxic substances known to man if ingested (breathing or eating). Unless you sucked on your uranium rock you’re probably ok.

  4. Uranium has actually been used in the making of inks or dyes for pottery. I have no idea why but it used to be the case. I’ve never heard of the pepople using the pottery or the people making the pottery showing any ill effects (and the people making it were likely exposed to a lot more of the stuff than the end user).

So, from a purely novice point of view the evidence would seem to suggest that you should not notice any ill effects from your minimal exposure to Uranium.

7

IIRC, some of the U oxides produce a very pretty yellow.

8

Nope- the main difference between U[sup]238[/sup], U[sup]235[/sup] and Pu is the half life, and chance of spontaneous fission. But, in all cases the vast majority of emissions are alpha particles, which as Bobort mentioned are nearly harmless when outside your body. In the very small percentage of cases where a nucleus fissions, it will give you hard gammas and neutrons, but that’s rare enough. Just don’t make a pillow or underwear out of weapons grade material.

However, breathing the dust into your lungs would be very bad, as the alphas would damage your mucosa and potentially lead to lung cancer. IIRC this is why Radon is considered a hazard - as a gas, it goes into your lungs where it can nuke you from the inside out.

9

I just asked my father about this. He used to work for Bedis Atomic (one of the first atomic power design/research firms) in the 1960’s and 1970’s. He says you’ll be fine, that exposure to a chunk of uranium ore small enough to fit in your pocket would be negligable and that the radiation from unrefined uranium is a pretty harmless form in itself (I suspect he means compared to ionizing radiation).

10

Some other posts woth more info from another time this topic was covered:

Uranium Question - Am I in Danger?

11

Did your mom’s collection contain any zircons? I understand
Zircon often has some thorium atoms substituting for Zircon,
as they’re chemically very similar. In green zircons especially, the thorium content is quite high and causes the
specimen to become increasingly turbid as the radiation (mostly alpha, I think), damages the crystal structure.

12

Um, this makes me wonder.

How much mass does it take for U or Pu to reach critical?

Seems to me that something the size of a softball of either element would have already exceeded criticality or at least have begun to trip the self-sustaining reaction threshhold.

I dunno. Maybe the stuff was refined, but still not yet pure enough to start percolating.

13

I had heard the critical mass for uranium was around 52 kilograms (or about 115 pounds). However, I have heard other estimates as low as 27 kilograms (source: http://boards.straightdope.com/sdmb/showthread.php?threadid=44233). Uranium is very dense but I don’t think a softball size chunk makes the cut for critical mass. Anyway, 27 kilos is around 60 pounds and unlikely to be carried by a weenie scientist in his outstretched hands.

FYI: I believe you need even less plutonium than uranium for critical mass.

Also, remember that even with a critical mass in your hands a nuclear explosion is unlikely. For a nuke to go off conventional explosives go off to compress the U or Pu as well as a neutron source to flood the whole thing with neutrons to kickstart the reaction.

It is possible for a critical mass to do all this on its own (I think) but not very likely (although you might get enough ‘mini-fission’ events in a critical mass to truly make it highly radioactive).

14

Just a WAG here…let’s say a softball sized chuck was about, oh, 20 lbs. While it wouldn’t go boom, I think it would be heating up pretty quickly.

Some dim recess of my very tired mind comes up with the recollection that the “physics package” of Pu consists of 2 half-spheres of highly polished material that, when slapped together, would be about the size of a grapefruit.

**Isn’t that for a fusion reaction? I think a fission reaction would result if there was simply enough mass in the area long enough for the sequence to begin. **

My physics professor depicted a scenario, like in the China Syndrome thing, when a reactor melted down, and the melted fissionable material ran together and reached what he called “secondary criticality.” Again, it wasn’t a “boom”, but more like an enormous release of all sorts of nasty-flavored, super-heated, smoke/steam/ash stuff. But it’s been a long time since I took physics.

I’m strictly speaking through my sphincter here. I wouldn’t know a physics equation from a grocery list.

15

I knew an old watchmaker & his hands shook a lot. I asked him why & he said from working on those watches that have a tiny tiny big of radioactive stuff on the dial that glows. I remember that stuff. So, a small amount can do it.

16

I used to work at a Department of Energy facility here in SW Ohio. I designed precision calorimeters that measured the heat output from radioactive elements (or any exothermic material). I calibrated our calorimeters using Plutonium. How? By picking it up with my hands and sticking it in the calorimeter! Of course, the Plutonium was triple-encapsulated in steel, so I wasn’t actually touching the stuff.

We had more than 10, but less than 100 Plutonium heat standards (I can’t tell you the exact number; it’s classified). Individual standards ranged anywhere from 0.000001 watts to 120 watts. I was handling these things all the time.

(You could usually hold the standards in the palm of your hand with no problem if they were below 1 watt. Above that, they were usually too hot to touch. You really had to be careful with the 60 watt and 120 watt standards, as they were quite warm (they were about the size of a beer can). You had to use tongs and asbestos gloves to handle them.)

While there was no danger of absorbing radioactive particles, these sources oozed radiation, and I’ve often wondered if I’ve been “damaged” in anyway.

I think I’m O.K., but my wife disagrees. :wink:

17

When I was a little guy (apprx 9) a friend and I were riding our bikes on a road. In the ditch we noticed a bunch of bottles that looked like shampoo bottles (short stubby ones). On them read (I am pretty sure about this) “Iridium 192” They were mostly empty, but some had some “granuals” (sp?) left over. I didn’t open them, but the guy I was with poured some in his hand. Oh yeah, did I mention that it had some strange symbol on it that looked kinda like a 3 bladed fan?

Well, I took one home and showed mom. I took it home in my pocket. She got a little concerned, phoned the fire dept who phoned some hazardous waste disposal team that picked it up and fined the company that “accidently” dumped them. I had to go to the hospital and the ran a geiger counter over me and my clothes, and only my shoes had a response. The fellow said washing them would be enough. I put that off as long as I could since I thought it was cool to have “radioactive shoes”. My friend in I got our cute mugs in the paper and that was that… except one thing that has stuck in my mind. My teacher, the next morning I am sure as an aside or joke mentioned “Well, lets just hope you don’t have kids that have 3 eyes or something”. That has always been in the back of my mind as an adult. I shouldn’t have to worry about anything, should I? I mean if the stuff only made my shoes barely radioactive and washing them was enough?

There, thats my story. Thats the first time I think I told someone since then. Don’t you all feel lucky? :slight_smile:

18

Having enough nuclear material in your hands to constitute a critical mass would most likely behave as your physics professor described it.

A critical mass is unlikely to fission fast enough to go BOOM. Fission is occuring inside the mass but not the runaway chain reaction required to release its energy quickly enough to explode and take out a city. Of course, as has been mentioned, the ‘little’ bit of fission happening in the mass does release the nasty radiation and would heat the mass up. Standing next to it would probably be a very bad idea.

Actually the explosives are used for both. As mentioned above a critical mass of nuclear material is unlikely to go BOOM on its own. For a typical A-bomb (fission) it is the explosives that crunch the material together that make building an A-bomb difficult. The explosives have to be very precisely placed and go off in a very precise fashion for everything to work properly. If they don’t do this they’ll more than likely blow the mass apart and you get no BOOM (but you do get nuclear material scattered all over the place). The idea behind this, I believe, is to make something called a ‘supercritical’ mass. The explosives seriously crunch the material together then neutrons bombard the mass to set off many more fission reactions at once than would occur naturally. Once this all starts you get the runaway nuclear fission that creates the devastating explosions.

As to an H-bomb (fusion) you actually have an A-bomb wrapped around the whole thing. Again, conventional explosives are used to detonate the A-bomb then the A-bomb provides the temperatures and pressures necessary to make the H-bomb part start its fusion reaction. The temperatures and pressures required to start a fusion reaction are far in excess of anything you’re likely to get from conventional explosives hence the need for an A-bomb component.

Interestingly H-bombs would be radiation free except for the need for the A-bomb used to detonate it. Actually, that’s not entirely fair, the actual explosion of an H-bomb would release all sorts of radiation but the H-bomb, I believe, wouldn’t have radioactive fallout but for the A-bomb component. This is probably a good thing as an enemy is less likely to lob nukes knowing that: A) Radioactive fallout might drift back across their own country and, B) the place you nuke isn’t going to be liveable for a LONG time. If someone thought they could nuke something and then move in a few months later with no danger to themselves they may, perhaps, be more willing to press the button.

19

Hey, I hit paydirt! Glowing green paydirt!

http://www.unitednuclear.com/uncrc.html

20

I’m not sure. I rarely looked at the collection. I mainly used the chest as a bedside table.