[ RadSafe ] Re: Leak Test MDA - Amended

Cary Renquist cary.renquist at ezag.com
Thu Sep 24 19:17:22 CDT 2009


The "MDA of 0.005 microcuries" is a paraphrase of the usual regulatory boilerplate statement which 
is often a minor variation of the following: 
  Leak tests should be evaluated by a method capable of detecting 0.005 microcuries of activity.

As you state, one should choose a MDA/minimum-significant-activity-level that will give 
you the "warm fuzzies" -- sufficient confidence that you can hopefully detect a problem 
before it becomes a !PROBLEM!.

There are other situations where you must have a lower detection limit, such as when you can't 
directly wipe a source because it is in a holder/etc, so you just wipe in the closest location
possible -- you need to be able to take action at a level lower than the 0.005 uCi.  


Cary Renquist
Direct:   +1 661-309-1033
cary.renquist at ezag.com

-----Original Message-----
From: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl] On Behalf Of alstonchris at netscape.net
Sent: Thursday, 24 September 2009 15:22
To: radsafe at radlab.nl
Cc: kharness at ohmartvega.com
Subject: [ RadSafe ] Re: Leak Test MDA - Amended


Sorry about the careless error in my first msg.  Please see below.

The figure you cite is the regulatory limit on removable activity, at which 
you must remove the source from service, and repair it or dispose of it. 
Clearly, if your MDA is not at least that low, you cannot demonstrate 
compliance. I would?think that most people would prefer, operationally, to have 
an MDA that is a relatively small fraction of the limit, so that you can act 
before the fact, if a source appears to be failing.  One reference is 10 CFR 35.67 (e).


-----Original Message-----
From: Harness, Kyle <kharness at ohmartvega.com>
To: radsafe at radlab.nl
Sent: Thu, Sep 24, 2009 9:06 am
Subject: [ RadSafe ] Leak Test MDA

Could someone please point me towards the reference(s) containing the
basis or calculation for the MDA of 0.005 microcuries in leak testing a
sealed source?  I can't seem to find it anywhere.  Or if you can't
remember the document, an explanation would suffice.  Thanks in advance
for the million responses I am going to get on this!


Kyle Harness

Radiation Safety Officer

Ohmart/VEGA Corp.

4241 Allendorf Drive

Cincinnati, Ohio 45209 USA

[tel]  513.272.0524 ext. 211

[cell]  513.432.4504

[fax]  513.272.4390

www <http://www.ohmartvega.com/> .ohmartvega.com

KHarness at ohmartvega.com

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