RE: Uranium Analyses

[Simon "M." Jerome <smj1@npl.co.uk>]

It is fairly staightforward. Use the following eqaution relating mass 
of isotope to activity;


                               [{Mass (in grams)} x {Avogadros 
constant} x {Natural logarithm of 2}]
{Activity (in Bq)} =  
---------------------------------------------------
-------------------------------------
                                         [{Mass number of isotope} x 
{half life (in seconds)}]

and therefore;

                                  [{Activity (in Bq)} x {Mass number of 
isotope} x {half life (in seconds)}]
{Mass (in grams)} =  
----------------------------------------------------
-------------------------------------
                                                  [{Avogadros constant} 
x {Natural logarithm of 2}]

Do this for each of the three isotopes, add up the mass results, and 
then compare them with the fluorimetry data.

You cannot use a conversion factor for 'natural uranium' unless you 
know that the isotopic ratio of the Uranium that of natural Uranium; 
this requires you to make a alpha spectrometry or mass spectrometry 
measurement.....

Hope that this helps,
 
>
>Can anyone on RADSAFE provide me some references on uranium analyses in
>environmental water? Specifically, I need to compare results for 
U-234,U-235,
>and U-238 produced by alpha spectroscopy with results calculated using 
a
>fluorometry method (ASTM-D5174-91).The fluorometry method uses laser 
light to
>excite the U and produces total uranium results in ppm. I have been 
provided
>U-234,U-235 and U-238 results along with the ppm results, but have not 
been able
>to find any consistent conversion factor to relate the ppm values to 
the
>isotopic values. This makes comparing alpha spec and the other results 
a hard
>trek. Any ideas? Please post to me at the address below:
>
>dale_dusenbury@mail.enr.state.nc.us
>

Simon Jerome
National Physical Laboratory
Centre for Ionising Radiation Metrology

E-mail:              simon.jerome@npl.co.uk
Internet:             http://www.npl.co.uk/
Telephone:     +44 181 943 6204
Facsimile:        +44 181 943 7004