[ RadSafe ] is uranium genotoxic? (was Re: CB interview on enrichedU)

Joe Nardi ajnardi at enercon.com
Thu Oct 27 16:37:43 CDT 2011

There is a lot of confusion over this issue that requires clarification.  

Reprocessed uranium is uranium that was recovered from the reprocessing of spent fuel that was irradiated in a nuclear reactor.  Because it was irradiated it will have other uranium isotopes present that are not found in natural uranium.  U-236 being a primary one because it has properties that are important to other steps in the fuel cycle.  The "reprocessed uranium" removed from the spent fuel will still be slightly enriched so it is also "enriched uranium".

If the reprocessed uranium is fed back into the enrichment facility (to increase the enrichment to the level needed by a nuclear reactor), it carries with it the U-236 into the enrichment cascades.

All depleted uranium is the tails (or leftover) uranium from the enrichment facility.  That is feed material (either natural or reprocessed uranium) in and tails (depleted uranium) and product (enriched uranium) out.

In the US enrichment facilities a lot of reprocessed uranium was used as feed uranium in order to reuse this valuable slightly enriched uranium.  The result is that enriched uranium and depleted uranium that are obtained from the US enrichment facilities will have traces of U-236 present.  (This is probably also true for other countries but I am not as familiar with their enrichment policies.)

The presence of the U-236 can be a handy marker to distinguish enriched and depleted uranium from natural sources of uranium which do not have the U-236 marker present.  At environmental levels of concentrations it is usually impossible to distinguish natural, depleted and enriched based on the ratio of the U-235 to U-238 because of the measurement uncertainties.  U-236 is not as easy to measure because of the low concentrations present but it can be done if you make a special effort.  But if it is found to be present then it is a clear marker that the uranium is not from a naturally occurring source.

I agree with the statement that the concentration of U-236 in depleted uranium is at such a low level that it would not be expected to substantially alter the radiological properties of the DU.  But is a great marker and I have used it in one instance to distinguish between enriched uranium and natural uranium in groundwater samples at concentrations that otherwise could not distinguish between the two.

So my take on this long thread of comments is that it is just a lot of noise at this point.  No one has presented sufficient data at this point, in my view, to conclusively say that the uranium found was really from a mysterious "enriched uranium" weapon vs. naturally occurring or depleted uranium.  If you did the U-236 measurements and found it present there would still be the question as to whether it was depleted or enriched uranium since both will have the U-236 marker but you would know that it was not from a natural uranium source.

A. Joseph Nardi
ENERCON Services
4490 Old William Penn Highway
Murrysville, PA 15668-1923
Phone: 724-733-8711 extension 236
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Email:  ajnardi at enercon.com

From: radsafe-bounces at health.phys.iit.edu [radsafe-bounces at health.phys.iit.edu] on behalf of Brennan, Mike  (DOH) [Mike.Brennan at DOH.WA.GOV]
Sent: Thursday, October 27, 2011 1:47 PM
To: The International Radiation Protection (Health Physics) MailingList
Subject: Re: [ RadSafe ] is uranium genotoxic? (was Re: CB interview on enrichedU)

Upon review of the document that you linked to, the problem becomes
clear: you don't know what you are talking about, and apparently don't
understand what you read.

The document you linked to said:

"Isotope analyses to determine the types of uranium present show that
0.0028 per cent of the uranium in the penetrators is in the form of
isotope U-236.  The presence of U-236 indicates that part of the DU came
from reprocessed uranium.  This information was provided by one of the
five laboratories being used by UNEP for its DU assessment work.
According to the laboratory, the content of U-236 in the depleted
uranium is so small that the radiotoxicity is not changed compared to DU
without U-236.  However, the final assessment by UNEP will be made only
once results from all laboratories are available."

This paragraph says several things.

It says that one of five labs found U-236 in very small amounts, leaving
open the question of whether the other labs also found it and hadn't
reported it, or hadn't found it, which in turn leaves open the question
of whether U-236 was present only in the samples that went to one lab,
or if it were missed by the other labs, or if it was identified by
mistake by the lab that reported it.  All are possible.

It also says that the presence of U-236 indicates that part of the
depleted uranium came from reprocessed uranium.  Reprocessed uranium is
not the same as enriched uranium.  Enriched uranium contains a greater
percentage of U-235 than natural uranium; usually in at least the
several percent range.  This article does not mention U-235, and given
the tiny, tiny amount of U-236 mentioned, one would expect that it would
have come up.

The article also clearly states that the samples were collected in
Kosovo, where there has never been any doubt that DU munitions were
used, presumably mostly against armored vehicles, for which it is most
effective.  It's use in Kosovo does not imply its use in Fallujah, where
there were no armored vehicles on the insurgent side.

Usually, if I cite something in support of an argument, it has something
to do with that argument.  Just saying.

-----Original Message-----
From: radsafe-bounces at health.phys.iit.edu
[mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of James Salsman
Sent: Thursday, October 27, 2011 6:32 AM
To: radsafe at health.phys.iit.edu
Cc: ecraft at edf.org
Subject: [ RadSafe ] is uranium genotoxic? (was Re: CB interview on

Mike Brennan wrote:

>... The idea that a lab identified "enriched uranium", supposedly
> from projectiles, is absurd.  Either the people in the lab didn't
> know what they were doing (possible) or their results were
> misrepresented (also possible).

It may be absurd, but it's not the first time this has happened.
Durakovic reported an isotope ratio indicating enriched uranium
in soil samples in Afghanistan, and the UN admitted some
reprocessed fuel had made it into some DU munitions in Kosovo:

Again, do you believe that uranium is a genotoxin or not?  The
literature is abundantly clear on the issue, and I wonder why
people on this list get so upset about the question.  Dr. Raabe
has stated quite clearly that uranium is not a genotoxin, and
Lt. Cherry has testified to that effect.  It seems like RadSafers
ought to be able to decide whether they believe them or the
peer reviewed literature reviews, or is that question just too
hard for a yes or no answer?

Steven Dapra wrote:

> Salsman gives a link to a paper by Craft, et al. in the Journal of
> Toxicology and Environmental Health, Part B, 7:297317, 2004.
> In its section on "DNA Damage/Carcinogenicity," (p. 308)
> Apparently Craft et al. are right alongside Dr. Raabe and
> Col. Cherry in not believing that DU is a genotoxin.

I am sending a cc of this message to Dr. Craft. I am not sure
she will appreciate how Mr. Dapra has characterized pp. 308-9 of

> I suspect Salsman's request that as a Navy veteran you can help
> him obtain statistics is a clever and  subtle way of insulting you

No, I honestly haven't been able to get anything out of the Birth and
Infant Health Registry, even though they were publishing annual
reports right up until 2001 when the birth defect rate for combat
versus noncombat 1991 Gulf War veterans started to skyrocket.  I just
thought Mike might be interested enough to help, too.  Does anyone
know a good FOIA attorney?

Now that it's 20 years out, will someone publish the cancer rate
statistics for those two groups?

James Salsman
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