View Full Version : Radioactive containment lead?

03-07-2008, 07:30 AM
I've read where some used the lead from radioactive containment shielding for casting. I'm just curious as to why it would not still contain whatever dangerious radioactive particles it absorbed "on the job".

03-07-2008, 07:44 AM
The way I understand it, lead was once uranium. But has decomposed from it's original form.

The lead used in containment, well I have read that lead does not absorb the radioactive particulates due to it's density.

Most folks would be alarmed if they had a Geiger counter with them right now where ever they are, it would be clicking away way more than you'd think.

We are bombarded with many rads every day.

Morgan Astorbilt
03-07-2008, 09:33 AM
Lead does not absorb radioactive energy. It would be useless as shielding if it did. Think of an X-ray room. If the 1/4" thick lead shielding absorbed radioactivity, while not letting it pass through, the interior of the X-ray room would soon become extremely radioactive.

03-07-2008, 09:47 AM
I've worked in nuke power houses, many times, and lead is one of the best shields they use to keep worker safe from ZOOMIES as they call rems. Another is water.
Radiation will neither pass through or be absorbed into lead.

03-07-2008, 10:15 AM
Its possible that alpha or beta particles could be left on the lead, only feasible if the containers once held radio-isotopes and the containment vessel broke inside the shielding container...but the containers are tested before they are released from the initial user. For a comparison on strength, gamma radation can be stopped by several feet of concrete, beta can be stopped by aluminium foil, alpha particles can be stopped by a piece of notebook paper....so put on your tin foil hat and keep casting.[smilie=1:

03-07-2008, 10:30 AM
I once had 600 lb of radcontainers in plastic containers on which rad warning was CROSSED OUT, which means they were tested with geiger counter and passed as safe. If the glass ampoule was broken or leaked there could? be radioactivity from salts contained in liquid, but very short lived(washing with a hose would remove and/or dilute any contamination. ps alloy assayed very similar to wheelweights, but much cleaner to deal with.

03-07-2008, 12:09 PM
I now understand that lead is a shield from radiation. This begs the next question. Lets take an xray facility in a hospital and say that the dangerous gamma rays "richochet" off the lead (I guess they have to go somewhere). Does this expose the neighboring room occupants to the radiation? Don't these rays have to wind up somewhere at a dangerous level?

03-07-2008, 01:07 PM
Gamma rays are absorbed by lead through several mechanisms (photoelectric effect, Compton effect, and pair production, if you want the terminology). These are ways in which the energy of the gamma rays are converted to other forms of energy. They do not leave the lead itself radioactive. It is like the Trijicon sights. The tritium in them is radioactive, and decays by emission of a beta particle, which is absorbed by the container, which then emits a photon of ordinary light. The container itself is not radioactive.

03-07-2008, 01:14 PM
So the lead is said to absord the radiation but renders it chemically/physically harmless?

03-07-2008, 02:00 PM
I use lead from the Nuclear Plant that I work at everyday.

I got about 750 pounds several weeks ago that they were throwing away. I just happened to be in the right spot at the right time to intercept it. Since they were chunking it, they let me have it.

All lead that is used for shielding must be checked before being released from controlled access which is considered to be a radioactive environment. About the only way for lead to become radioactive is for surface contamination to become embedded it in. Lead, being soft, can absorb particulate matter into the skin of it. As most lead is painted now, for environmental concerns, the paint can become contaminated from particulate radioactive matter. Usally it is not a problem, but if the lead being checked is shown as raido active, you can bet that it is not the lead itself, but some radioactive trash that got stuck in the outer layer.

If the lead is being disposed of in a normal manner, it wont be "hot" or radio active. I've been using lead for years. We used to use a lot of brick, that wieghed 30 pounds. We have made many a round ball and maxi ball with it for muzzle loaders. The lead is pure, so to make good bullets it needs to be alloyed.

We used to recover some tin babbit bearings from our turbines that got changed out, and alloyed with that it makes exellent bullets, no different that the Lyman No. 2 alloy. Good stuff.

03-07-2008, 02:04 PM
So the lead is said to absord the radiation but renders it chemically/physically harmless?

I dont know how exactly is does it, but it does work. We have lots of lead blankets for hot spots that are used to shield valves that are radiocative.. The blankets are filled with lead shot and sewn together and then placed on the pipe or valve that is "hot". It shields it to the point that you can walk up to it and not get any dose. Remove the blankets and stand there and you will get a "dose" of radioactivity. Any amount of dose is to be avoided.

03-07-2008, 02:51 PM
I believe that the lead, paper, or water shielding that cannot undergo atomic decay at the energy levels of the radiation involved simply absorbs the energy of the various particles that strike it by converting that energy to heat, resulting in a slight temperature rise. No different that having your black cast-steel lawn bench heat up enough to blister your a** :shock: by absorbing photons from the sun on a clear day. Don't ask me how I know!

03-07-2008, 04:21 PM
As for beta and alpha particles, beta particles are electrons. Alpha particles are helium nuclei. When they lose their high velocity and the charges redistribute and equilibrate, there's nothing left to cause any toxic or radioactive concern.

03-07-2008, 06:25 PM
Here's another way to think of it. A radioactive substance is one which emits high speed particles (alpha or beta) or ionizing radiation (X- or gamma rays). They can be dangerous, depending on what they emit, how much they emit, and your distance from them. The materials that absorb the particles or radiation without re-emitting anything (except visible light) are not dangerous.

There is a story of a military instructor in the 50s who asked a class of soldiers if they knew the difference between radiation and contamination. One answered "Radiation is when you smell manure. Contamination is when you step in it."

03-07-2008, 06:41 PM
"Radiation is when you smell manure. Contamination is when you step in it."

Dang, I been Contaminated! :holysheep

03-07-2008, 06:44 PM
Think of the high speed particles and gamma rays as bullets in flight. Think of the lead as a nice soft pile of sand. Once the bullets hit the sand and come to a stop, they are no longer dangerous. I could continue on, but I keep coming up with a vision of a happy cat spotting the sand pile...

03-07-2008, 09:19 PM
Thanks everyone.