Re[2]: Uranium Analyses

[Ruth Weiner <rfweine@sandia.gov>]

I guess the old professor is showing through. Why use an approximate conversion 
factor? If you know the U234/U238 ratio, you can convert using the relationship:

Activity in Bq = (ln2/halflife in sec)*(wt/atomic wt)*6.02E23

Clearly only my own opinion

Ruth F. Weiner
Transportation Systems Department
Sandia National Laboratories
505-844-4791
fax 505-844-0244
rfweine@sandia.gov


______________________________ Reply Separator _________________________________
Subject: Re: Uranium Analyses
Author:  Holloway3@AOL.COM at hubsmtp
Date:    3/15/98 10:59 AM


<< An excerpt reads:  "In the 1991 proposal EPA solicited comment on use of a
 conversion factor of 1.38 pCi/g or 0.67 pCi/g.... In today's rule the Agency 
 is selecting the lower conversion factor, 0.67 pCi/g, because it is a 
 conservative factor that is based on the 1:1 activity ratio of U-234 to U-238 
 characteristic of
 naturally occurring uranium." >>
     
Any conversion factor such as the one above can be considered only as a gross 
approximation, because the actual ratio of U-234 to U-238 in water can vary 
enormously, usually from 1 to 10 (activity ratio).  From what I have seen, it 
is more often nearer to 2, than to 1.   If one is willing to accept an 
uncertainty of 100% or more, then I suppose the above conversion factor is 
acceptable.