Re: U-235 in Natural Uranium

["Philippe Duport" <pduport@uottawa.ca>]

Leo,



I do not  remember having seen data on the variability of the U235/238 ratio

in U ores.  One would think that the U235/238 ratio is quite constant and

stable everywhere in the Earth crust, except where nuclear reactions

occurred naturally.  There are no reports of other Oklas.  There are no

mechanisms other than nuclear reactions and isotopic separation to change

the isotope ratio in natural elements.  Then, except at fossil reactors, the

U235/238 ratio should be constant everywhere, as are the C14/C14 and

K39-K41/K40 ratios.



In particular, the C14/C12 ratio is considered constant enough to be used

for accurately dating prehistoric artifacts.



Philippe Duport



----- Original Message -----

From: "Leo M. Lowe - SENES Consultants Limited" <llowe@senes.on.ca>

To: <radsafe@list.vanderbilt.edu>

Sent: Tuesday, June 12, 2001 9:18 AM

Subject: U-235 in Natural Uranium





> Hello All:

>

> Does anyone have any literature/information on the normal variability of

> the U-235 concentration in naturally occurring uranium in ores and soils

> i.e. 0.72% +/- ??.  I understand that the NRC considers depleted uranium

> (DU) as uranium depleted below 0.711% U-235.  Does this then mean that

> natural uranium does not exhibit U-235 levels this low (except in unique

> circumstances such as the Okla natural reactor)?

>

> Thank you.

>

> Leo M. Lowe, Ph.D.

> Principal, Senior Health and

> Environmental Physicist

>

> SENES Consultants Limited

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> e-mail: llowe@senes.on.ca

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