Re: Question on Radioactive Source Disposal

["Michael Kay" <makay43@attbi.com>]

If the sources were pure Po-210, they can be scraped clean of all

radioactive signs and labels and tossed in the trash. After 10 years that is

about 25 half-lives, and there is will be no radiation detectable over

background no matter how sensitive the counter.



That said, it is imperative to count the sources because they may actually

be Pb-210 (old nomenclature RaD) with a half life of 22.6 years. The

observable gammas come from the daughters Bi-210 (RaE) and Po-210 (RaF). If

the sources are still active, that will indicate the presence of RaD or one

of the other long lived parents of Po-210.



Michael Kay, ScD, CHMM

makay@alum.mit.edu

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

From: <hacare@MINDSPRING.COM>

To: "Radsafe Vanderbilt" <radsafe@list.vanderbilt.edu>

Sent: Saturday, April 13, 2002 11:35 AM

Subject: Question on Radioactive Source Disposal





>

> A local high school finds themselves in possession of two 0.1 microcuries

sources of PO-210  (half life 138 days).  The sources pre-date the current

teacher who has been there over ten years.  Therefore the activity in the

sources should be down around ten orders of magnitude.  The school wants to

get rid of these things.  Is there a minimum activity level where a source

can be disposed of as clean waste.  If not, does someone know of some way to

legally dispose of these without it costing and arm and two legs??

>

> Hal

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