RE: Pb Bricks and Audits

[jdelahunt@cc.colorado.edu]

>1.  This seems a perfect match (since lead bricks are often the source
>of problems at audits!).  Regarding the lead brick issue at Colorado,
>I think a source of "virgin" lead is highly desirable (especially if
>the shielding application is for high sensitivity detector caves).  A
>surprising amount of recycled lead has multiple detectable peaks (I've
>seen cesium and cobalt) of sufficient magnitude to cause MDA problems.

The application is source shielding - we just want enough
lead to show state health that someone who sleeps, eats and
works in the office next to the storage room will have an
exposure less than 50 mrem/year.  As I said before
(privately), they aren't overly concerned about compton
effects, just about the number of TVL's we have.

I've heard this lead contamincation thing before, though
(from one of the brick suppliers I talked to this morning).

>Of course, depleted uranium is great "small TVL" material, but there
>seem to be a lot of control questions about it!  The army might have
>some nearby you if they have been holding artillery practice near Fort
>Carson in the last few years (DU armor piercing ordnance).

The problem with DU is that it has the U at the end.  Even
though it's a better shielding material (cubic inch for
cubic inch), state health will still (I'm guessing) have an
issue with it.  

"You're shielding your gamma sources with URANIUM!"

<sound of license tearing>

Just a thought.  We may have mountains and stuff, but we
don't have the most educated regulators.  I'm ever so fond
of my job, especially when regulatory compliance flies in
the face of common sense.  *sigh*


Thanks for all the leads on brick suppliers.  I think we've
got it hammered out.

John

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