Re: HPS N13.30

["Wesley M. Dunn" <WDUNN@brc1.tdh.state.tx.us>]

It appears to be based on the difference in effective half-life. 
If you are running a routine bioassay program (as opposed to an 
incident-based program), you need a much lower detection level to 
find what's left behind.  This is necessary to account for activity
that is "removed" from the system.

Wes

> Date sent:      Tue, 1 Oct 96 09:39:31 -0500
> Send reply to:  radsafe@romulus.ehs.uiuc.edu
> From:           Slaback@micf.nist.gov
> To:             Multiple recipients of list <radsafe@romulus.ehs.uiuc.edu>
> Subject:        HPS N13.30

> Having just received the mailing from HPS,
> may I pose a question:
> Table C.1 shows the MDC for C-14 and S-35 
> to be the same (as would be reasonably expected).
> 
> But table 2 shows for a Minimum Testing Level (MTL)-
>   C-14   2 kBq/L
>   S-35   20 Bq/L
> 
> Why the difference?
> 
> 10CFR20 ALI's are not that different -
>   C-14 compounds  2E+3 uCi, CO 2E+6, CO2 2E+5
>   S-35 vapor      1E+4 uCi, other forms 2E+3
> 
> The discussion for selecting an MTL is based on the
> MDA (MDC), so why is such a lower number assigned for
> S-35?
> 
> P.S.  The HPS is to be commended for the wide distribution
> of this standard.  It has lots of good info.  In particular
> I like the inclusion of the backup data to show the basis
> for their various recommendations and the detailed statistics
> discussion.
> 
> A little risk adds spice to life.
> Lester.Slaback@NIST.gov
> 
*********************************************************************
Wesley M. Dunn, CHP                        512-834-6688
Deputy Director, Licensing                 512-834-6690 (fax)
(Texas) Bureau of Radiation Control        wdunn@brc1.tdh.state.tx.us
*********************************************************************