Re: Beta rule of thumb

[Keith Welch <welch@CEBAF.GOV>]

Randy,

Mark is asking about a ROT, which, by nature incorportates a bunch of
assumptions, and he's also truncating the units (all good rad-techs speak a
shortened form of the incredibly cumbersome techno-jargon which abounds in
HP).  Apparently it's been too long a week - you're over-analyzing :)

Anyway....
Mark, my old rule o' thumb gives slightly different levels for the gamma.
But it's in the ballpark.  I get 2,000,000 dpm to one mrem/hr.  But what's
a million dpm among friends.  My beta dose rate conversion is a factor of
100 higher.  i.e. the same 2 million dpm gives 100 mrem/hr or conversely,
it only takes 20,000 dpm to yield 1 mrem/hr.

Anybody have numbers terribly different from this?

---------------------
>Date: Thu, 02 Oct 97 10:49:34 EST
>From: "Norman Randy" <rnorman@smtplink.microbio.com>
>Subject: Re: Rule of Thumb for BETA contamination
>
>     Something escapes me here...isn't dpm "decays PER MINUTE" and mrem a 
>     unit of dose? The dose received via exposure to a certain number of 
>     dpm (or uCi, etc.) depends (among many other things) upon the total 
>     time of exposure. The same activity can yield a very low dose or a 
>     very high dose, depending upon the amount of time one is exposed, no??
>     
>     I though this was a basic concept...am I missing something here? Are 
>     there assumptions being made that are not explicitly stated? 
>     
>     Come on now, it's already been a long week..no fair playing games with 
>     my head!
>     
>     Randy Norman
>     Safety Manger, RSO, CHO, BSO, etc.
>     MA BioServices, Inc.
>     Rockville, MD
>     rnorman@microbio.com
>
>
>______________________________ Reply Separator
_________________________________
>Subject: Rule of Thumb for BETA contamination
>Author:  radsafe@romulus.ehs.uiuc.edu at INTERNET
>Date:    10/2/97 8:46 AM
>
>
>The rule of thumb conversion for removable contamination has been 1 mrem 
>gamma = 1 million dpm
>assuming Co-60 as the major isotope does anyone have a rule of thumb for 
>1 mrem BETA ? 
>     
>I'll welcome any input 
>
Keith Welch
Thomas Jefferson National Accelerator Facility
Newport News VA
welch@cebaf.gov
Ph: (757)269-7212
FAX:(757)269-5048