Re: External Dose Constants for Beta Emitters

["joseph guido" <joseph_guido@pc.radian.com>]

     oops - forgot one sutle point ... this assumes that the source is an 
     infinite plane with activity of 1 uCi/cm^2 ... this may not be all that 
     bad since for the energies in question it would not take that large a 
     source to be considered infinite ... 
     
     
     
     Hows this for a possible (and easy) solution: To get ballpark estimate 
     of hazard (I assume this is all you want) use the Federal Guidance 
     Report-12 (FGC) dose coefficients for exposure to contaminated ground 
     surface (Table III.3) to estimate the dose rate to a human phantom 
     which is directly over the source. 
     
     for exposure to contaminated ground surface - 
     
     Dose Coefficients hT (Sv per Bq s m^-2), are as follows* 
     
     
     H-3,              0 
     C-14,      1.61E-20
     P-32,      2.91E-18
     P-33,      4.46E-20
     S-35?      1.68E-20
     
     *note: to convert to mrem per uCi y cm^-2, multiply by 1.168E21
     
     the dose equivalent rate (in mrem/hr) for a 1 cm2, 1uCi source would 
     be:
     
     H-3        0
     C-14       0.002
     P-32       0.4
     P-33       0.006
     S-35       0.002
     
     
     Any opinions on this solution???
     
     
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______________________________ Reply Separator _________________________________
Subject: External Dose Constants for Beta Emitters
Author:  radsafe@romulus.ehs.uiuc.edu at INTERNET 
Date:    5/25/95 11:08 AM
     
     
     Radsafenetters, I am not a HP although I subscribe to this 
     list.  Many years ago I have studied Radiochemistry, 
     attended radiation safety courses and used radioisotopes 
     (low levels) in my research activities, but I do not recall 
     to have ever known the existance of tables reporting 
     Specific Dose Constants for beta emitters.  There are 
     tables for Specific Gamma Ray Dose Constants in units of 
     (mSv/h)MBq at 1 meter from a point source, but I have not 
     found similar tables for beta emitters, not even for hard 
     beta radiation.  Could any radsafenetter out there help me 
     to estimate the external dose-equivalent rate from an 
     unshielded point sources at a distance of 1 meter or 1 foot 
     (or whatever unit) for the following nuclides:  
     
     
     Thanks for your help.
     P.S. Someone told me that the dose-equivalent rate for H-3 
     at 1 foot from the point source is 1 (mrem/h)mCi.  Is this 
     an acceptable value?
     Vincent N. Finelli, Dir.
     Environmental Heath & Safety
     Florida Atlantic University
     Boca Raton, FL 33431
     E-mail: VFinelli@acc.fau.edu