Re: Re:Radionuclide in rubber products

[daleboyce@charter.net]

_Most_ plastics and rubbers do not contain much in the way of radioactive

material incorporated into them.  Not even C14, since the petroleum is so

old the C-14 in it originally has long since disappeared.  The refining

process removes any norm from the raw materials before the manufacture of

the end polymer.



An exception to this is some rubber was manufactured in an event in the 90's

in which lead powder was added to it to make lead aprons. The lead that was

added had been refined from the dregs of tin ore (I believe it was

Cassiterite SnO2) instead of lead ore (Galena). Pb210 from uranium in the

ore refined with the lead. Resulting in a whole bunch of lead aprons and

such that were slightly radioactive.



Also some composites can be radioactive.  I learned the hard way that G10

one of the fiberglasses that is used for circuit boards has enough thorium

in it to make its inclusion in a low background detector design a bad idea

;)



I would agree that the most likely culprit are the radon progeny. Many

rubber compounds are easily static charged. They have an interesting way of

playing tricks on HP's.  Examples of contamination with radon progeny from

both Rn220 and Rn222  I have either personally seen or heard reported

include electric fan blades, electric fences, air filters (you might expect

it in exhaust filters, but I have seen it on intakes filters as well). I was

once concerned when the exhaust filter of a hot cell that had not been used

in many years was hot when it was changed out. A check a couple of days

later and it was cold. Pretty much anything at a potential or with static

charge especially if it sees a large airflow is to be suspected of the

possibility of those rascals.



Dale





----- Original Message ----- 

From: "Mccormick, Luke I" <LUKE.Mccormick@dhs.gov>

To: <brees@lanl.govATUSCUSTOMS>; <radsafe@list.Vanderbilt.Edu>

Sent: Wednesday, July 07, 2004 4:09 PM

Subject: Re:Radionuclide in rubber products





> Brian,

> Many syntretic rubbers are made from petroleum. So I would expect to see

> radium or other U or Th progeny as in the oil & gas wells.

> Luke McCormick

> US Customs & Border Protection.

>

> ____________________Reply Separator____________________

> Subject:    Radionuclide in rubber products

> Author:     owner-radsafe@list.Vanderbilt.Edu

> Date:       7/7/2004 11:08 AM

>

>

>

>

>        I was talking to somebody about portal alarms, and they said

>        they'd seen

>        alarms from rubber (large rolls).  We don't have the ability to

>        go back and

>        gamma-spec them, does anyone know what the likely nuclide was?

>

>        Thanks,

>        Brian Rees

>

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