nuclear antiques

[Backwoods_VT]

I have a silly question that my friend asked and i cant answer, but maybe someone here can. He collects old fly reels, which look like they are made from aluminium, but years ago in the fourties and fifties, how did they know that they werent accidentially mixing in other elements while making one specific metal. Could some uranium accidentaly be in the mix? Im a long way from a metalurgy expert, but when making one type of metal how do you sift out all the other junk you dont want in the mix? So in theory could old metals have radioactive elements accidentaly mixed in? Thanks guys.

 

[mete]

You could always check it with a gieger counter ! At this point in time the biggest problem with unwanted elements is from recycling. While some of the steel is within spec, there may be enough elements to make a difference in heat treating or forging, etc. This is especially true of structural steel.The special steels ,stainless and tool steels are more carefully made. In the extraction of copper the amount of copper in the ore is very small but there are other things with it such as gold and silver .These are very carefully separated as they are very valuable.

 

[mwerner]

Difficult to imagine how any sort of heavy metal like uranium could have been mixed with aluminum; most aluminum that's used in making such products is alloyed, but nothing like uranium.

Ever cast bullets? Steel floats like a cork on top of molten lead.

 

[TorzJohnson]

I may be wrong but isn't uranium rare? I think they have to process tons of ore to get a little uranium. I would be surprised if any of it could accidentally end up in common metal products.

 

[DaveH]

mete brings up a good point. there have been some cases of old radioactive isotopes being recycled into metal products. I've only heard of that happening in Mexico, but I suppose it could occur in other places.

 

[Gollnick]

I may be wrong but isn't uranium rare? I think they have to process tons of ore to get a little uranium.

That's true of most any metal. Sometimes there are very pure veins, but those are very much the exception.

Uranium is actually remarkably common, about 40 times more common than silver and 500 times more common than gold.

However, there is very unlikely to be any more than the very slightest of traces of it in aforementioned fishing reels.

Keep in mind that uranium is very heavy, much more so than aluminum.

I would actually question whether or not a fishing reel from the 1940s or 1950s is made of aluminum. While it's so common today that we make pop cans out of it, 50-60 years ago aluminum was pretty exotic, expensive stuff. In the kitchen today, we sometimes wrap foods in a aluminum foil; but we often call it tin foil. The reason for that is that until fairly recently it was tin foil.

Anyway, most uranium is not highly radioactive and is, in fact quite harmless. It's all around us, in the dirt and in the dust and in the air we breath (don't tell the environmentalist whackos). And it's not there because of atomic bomb tests or nuclear power plants but rather because uranium is part of nature.

If your friend has some concern, a simple Gieger counter will answer the question. Of course, the next question is where to find one. Metal scrap dealers will have one. Any college or university chemistry or physics department should. Hospitals usually do too.

 

[Gollnick]

mete brings up a good point. there have been some cases of old radioactive isotopes being recycled into metal products. I've only heard of that happening in Mexico, but I suppose it could occur in other places.

Oh, there have been some very dangerous cases in the US, but mostly involving cobalt sources. These sources are used in industrial processes, especially testing. Metal parts and welds are often tested this way. You put a piece of special film on one side of the part and you put the source on the other. The source is enclosed in a shielded housing, but it has a shutter window that can be opened remotely. In the resulting picture, you can detect cracks in the metal and voids and pinhole leaks and other flaws in the weld. It's a very effective test. But, there have been several cases where these sources have gotten into the recycling stream. This is why metal recyclers have Gieger counters.

Another common use of such sources, though usually smaller, is the so-called guages used to test concrete and asphalt. This device is basically a Geiger counter and a source mounted across from each other on opposite sides of a test chamber. Again, the source is highly shielded and has a remotely-operatable shutter. You first empty the test chamber and close the lid on it. Then you open the shutter and note the measured radiation level. Close the shutter. Open the chamber door. Insert the sample to be tested. Close the chamber door. Open the shutter and measure the radiation level observed with the sample between the source and the counter. Good quality concrete and good quality asphalt both absorb a lot of radiation.

We've had several all-points-bulletin alerts in the Portland area in recent years to find stolen trucks carrying these guage devices. In all cases, the stolen truck has been found and guage has been recovered intact. And in all recent cases it has been obvious that the thieves had no intention to steal the guage; they wanted the truck and were unware of the guage. The concern here really is that the source is highly radioactive and could sicken someone exposed to it closeup. The guage mechanisms, of course, have all sorts of interlocks to protect the source. But, if someone wanted to, they could certainly get into the source.

 

[JCaswell]

Fun with Gieger Counters:

If you get your hands on a Gieger counter (particularly the type that has a meter and the classic audible 'ticking' feedback) try holding it next to a brick, you may be surprised to hear that baby 'take off' with an alarming-sounding profusion of 'ticks'. Go outside and hold it in direct sunlight. If you can, go into a cave.
Don't freak out if something seems a bit reactive since sticking the thing in a hole will get a response. It all seems pretty alarming until you get around something really hot (which isn't all that easy for most of us to do by accident) then you'll have something to compare with it.