[ RadSafe ] Pepto-Bismol
eic at shaw.ca
Fri Dec 15 08:50:22 CST 2006
I don't think the statement "...The enrichment process takes U-235 from 0.7%
to about 3.5% so the DU should have 1/5 as much U-235 as natural uranium.
..." follows logically. In order to balance U-235 quantities, you must
balance percentages of U-235 in the mixture multiplied by quantities of the
For example, if you start with 1000 t of natural U and end up producing 1 g
of 3.5% U-235 enriched U, you will not see any significant depletion in the
1000t - 1g of material that are left.
Dan McCarn mentions an interesting mechanism about the U234/U238 ratios in
ground water. I don't think it can be used to explain such a huge increase
in U-234 activity in global average DU. We have close to 100% recovery in
ores leached in a mill. Even in ISL operations, they try for +75% recovery.
I think, if the recovery is low, the explanation is that macroscopic pieces
of ore don't get contacted by the solution. So, you probably leave both U234
and U238 in the ground.
----- Original Message -----
From: "Bernard L. Cohen" <blc+ at pitt.edu>
To: "Michael McNaughton" <mcnaught at lanl.gov>
Cc: "Flanigan, Floyd" <Floyd.Flanigan at nmcco.com>; <radsafe at radlab.nl>
Sent: Thursday, December 14, 2006 1:24 PM
Subject: Re: [ RadSafe ] Pepto-Bismol
> Natural uranium should have the same alpha activity from U-238 and U-234
> (they are in secular equilibrium).. The enrichment process takes U-235
> from 0.7% to about 3.5% so the DU should have 1/5 as much U-235 as natural
> uranium. Enrichment shoud remove a somewhat larger fraction of U-234 (it
> is lower in mass) than of U-235, so the U-234 alpha activity in DU should
> be somewhat less than 20% of that in natural uranium. Even if it was 20%,
> it would be 0.2/ (1+0.2) = 17% of the total alpha activity. How can it be
> as much as 28%?
> Michael McNaughton wrote:
>> According to figure 2.2 of DOE-STD-1136-2004, about 28% of the total
>> alpha activity of DU is U-234.
>> At 06:01 PM 12/13/2006, John R Johnson wrote:
>>> What do you mean by "pure depleted uranium"? Producing U-238 without
>>> U-234 is very difficult.
>> Mike McNaughton
>> Los Alamos National Lab.
>> email: mcnaught at LANL.gov or mcnaughton at LANL.gov
>> phone: 505-667-6130; page: 505-664-7733
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