[ RadSafe ] thresholds in radiation portals

Marco Caceci chemitech at chemitech.com
Wed Sep 15 13:30:49 CDT 2010

I just found out that (reportedly) Italian standard UNI 10897 for radiation
portals requires a "sensitivity" of 50kcps/μGy*h-1. Maybe with Cs137? It
seems tough to me.

Glad to start a discussion of the meaningfulness of this and equivalent
parameters when for example drift is not specified (some systems are just
thermometers.), but I post because I have two questions that colleagues on
this list may answer and I can't:

- How prevalent is the practice of setting the alarm threshold in radiation
portal monitors at say 25%, 50% or 100% above background (as opposed say to
the "2.85 sigmas above background" necessary to comply with common

- Are there industry standards that suggest, recommend or impose thresholds,
say 3 sigma, 10% above BG, or whatever, for the setup and operation of
radiation portals? Or can an enduser buy a unit that detects 1 nGy signal,
set it to alarm at 100 nGy, and get away with that?

The answers would help me and others understand the relevance / significance
of specifications and requirements that, I must say this, in my humble
opinion, are often just ways to increase revenue to manufacturers (with less
money left for the workers, I suppose).

Thank you all in advance,


Dr. Marco Caceci
L.Q.C. s.l.u., Vilabertran 15, 17130 La Escala, Spain
tel +34 902 88 4887 (tel)
mob +34 607 07 1196 (mob)
fax +34 972 98 0591 (fax)
web www.chemitech.com
email chemitech at chemitech.com

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