[ RadSafe ] Basis or Bases for Sealed Source Leak Test Detection Level

[John Jones]

Henry,

I'm not the best source for information on this, but it made me wonder.

Currently, 185 Bq is relatively easy to detect depending on the instrument used.  That activity is equal to 11,100 DPM, and a standard liquid scintillation counter easily measures 40, 50, 60 DPM.

I found the following in a procedure on another university's web site.
	The basic rationale for this criterion is that a non-leaking source will exhibit only background activity levels on leak tests, whereas a source that is leaking enough to present a health hazard will be easily identified at the required detection level.

John
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John P. Jones
Radiation Safety
435.797.3514
john.p.jones at usu.edu

-----Original Message-----
From: radsafe-bounces at health.phys.iit.edu [mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of roseb at gdls.com
Sent: Friday, June 17, 2016 12:38 PM
To: The International Radiation Protection (Health Physics) Mailing List <radsafe at agni.phys.iit.edu>
Subject: [ RadSafe ] Basis or Bases for Sealed Source Leak Test Detection Level

Does anyone subscribed to this list know off-hand what the basis is or bases are for the 185 becquerel (0.005 microcurie) detection level for sealed radioactive sources?  Does the level have a technology basis (e.g. 
level of detection capability for a measuring instrument) or a health basis (committed or effective dose due to exposure at the stated detection level)?

This leakage detection level appears to apply for most sealed sources whether used for brachytherapy, industrial radiography, or other industrial or research application that uses specifically licensed sources.  It also appears to apply regardless of radioisotope contained in the sealed source (exceptions include certain tritium devices and exempt quantity sources).

I am aware of ANSI N44.2-1973, leak-testing radioactive brachytherapy sources (I do not have a copy of this standard to see if it provides the basis or bases for the stated level).  I am not able to locate anything online that provides basis or bases for 185 becquerel (0.005 microcurie) being the seemingly universal lower limit of detection for leaking radioactive sealed sources.

Henry

Boyd H. Rose, CM, CIH, CHMM, EI
Sr. Safety and Environmental Engineering Specialist Corporate Radiation Safety Officer General Dynamics Land Systems
38500 Mound Road
Mail Zone 436-10-80
Sterling Heights , MI 48310-3200
Tel: 586 825 4503
Fax: 586-939-4140
E-mail: roseb at gdls.com

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