RE: uranium in drinking water 234/238U ratio

["Bradshaw, Keith" <Keith.Bradshaw@nnc.co.uk>]

Rodney/Radsafers

It's not at all unusual for natural waters to be enriched in 234U compared
to 238U.  It's due to the increased leachability of the U-234, since it's an
alpha decay product that has been knocked out of its mineral lattice
position by recoil.  The activity ratio in seawater is 1.16.  A ratio of 2.3
does seem to be on the high side of what I've observed, but I'm sure its
within the range of literature values.

This also means that the activity concentration of "natural uranium" of
25.4Bq/mg does not apply in this case.  In fact it's higher, and perhaps the
cause of the apparent discrepancy in mass and activity concentrations.  No
time to work this out now tho'

Personal views only

Regards

keith.bradshaw@nnc.co.uk

> -----Original Message-----
> From:	Rodney Bauman [SMTP:RBauman@wssrap.com]
> Sent:	Tuesday, October 10, 2000 8:48 PM
> To:	Multiple recipients of list
> Subject:	RE: uranium in drinking water
> 
> What's the explanation for the U-234/U-238 ratio of 2.3?  One might expect
> such a discrepancy at concentrations near the MDC (i.e., due to counting
> statistics), but not at hundreds of pCi/L.  I would seriously question
> this
> data due to this inconsistency.
> 
> Rodney Bauman, CHP, RRPT
> rbauman@wssrap.com 
> 
> -----Original Message-----
> From: Charp, Paul [mailto:pac4@cdc.gov]
> Sent: Tuesday, October 10, 2000 8:12 AM
> To: Multiple recipients of list
> Subject: uranium in drinking water
> 
> 
> We have been involved with this situation for about a week.  The uranium
> data we have received thusfar is that the uranium analysis was performed
> by
> gamma spec with the following results listed as pCi/L:
> 
> U-nat     758 +/- 140  mda 0.8
> U 235    7 +/- 2         mda 0.5
> U 234    512 +/- 95    mda 0.8
> U 238    224 +/- 42    mda 0.7
> 
> the total alpha was measured at 882 pCi/L with no indication of the method
> used for this analysis
> 
> 


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