RE: U-235 in Natural Uranium

[Sonter Mark <sonterm@EPA.NSW.GOV.AU>]

Did anyone ever do an isotope ratio check (Oklo check) on Cigar Lake??



Mark Sonter



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

	From:	Philippe Duport [SMTP:pduport@uottawa.ca]

	Sent:	Wednesday, 13 June 2001 4:26

	To:	Leo M. Lowe - SENES Consultants Limited;

radsafe@list.vanderbilt.edu

	Subject:	Re: U-235 in Natural Uranium



	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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