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Re: [Phys-l] lead brick



My story -- not nearly as interesting:

When I was shielding my C-14 multi-element prop. counter w/ steel, Bob Eisberg told me to require purchasing to specify pre-1945 smelted steel. Curiously I don't remember how we got it up to the second story lab.

bc remembers finding little improvement shielding a xtal scintillator w/ lead bricks.

On 2009, Oct 15, , at 13:14, Edmiston, Mike wrote:

Story: Getting lead from a nuclear facility was mentioned. Depending on the age of their lead, they may not want to part with any of it. Lead smelted or otherwise processed after atmospheric nuclear testing is contaminated with fallout at sufficiently high levels that it is worthless for shielding purposes for low- background counting chambers. Post-nuclear-testing lead can be used for shielding personnel, but not for shielding gamma detectors from background radiation. The background count rate actually goes up when the detector is put into lead shield made from post-fallout lead.

A source of pre-nuclear-testing lead is ballast from decommissioned ships built pre-nuclear-testing. When I was a graduate student at Michigan State University Cyclotron Lab, our lab director procured the lead ballast from a decommissioned submarine. I remember it well, because when the flat-bed truck arrived in East Lansing, the graduate students formed a "bucket brigade" to unload the lead bricks from the truck and get them into the storage place in the lab. My arms and back were sore for a couple days after that.

If you ask a nuclear facility for a lead brick, and what they have is a limited supply of pre-fallout lead, they're not going to want to give it to you.