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Re:Activity Ratios in "Natural Uranium"
NCRP 94, Section 4.2.1 has a good discussion of natural decay series
radionuclides. Since U-234 and U-238 are from the same decay series, it lists
more information for that ratio than it does for U-235/U-238, but I did find
this:
"Through geologic time, the mass ratio, U-235/U-238, has decreased by the faster
decay of U-235 to its present value of 0.0073; the ratio is fairly constant even
where disequilibrium is present..."
Based on my reading, I'm wondering why you need to so carefully assess the
U-235/U-238 ratio. You may have already considered this, but I'd be much more
concerned about getting my arms around the U-234/U-238 ratio (because U-234
contributes so much more to the total nat U activity per unit mass than does
U-235). Also, I gather from NCRP 94 that the U-234/U-238 mass ratio is much
more variable than that of U-235/U-238.
Isabelle Fisenne at DOE's Environmental Measurements Laboratory might be a good
one to contact on this issue. I can't help with solubility issues, sorry.
Hope this helps,
Elizabeth Algutifan
Weldon Spring Site
Elizabeth_Algutifan@wssrap-host.wssrap.com
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