Re: How DU was used in the production of Pu

[Bernard L Cohen <blc+@pitt.edu>]

	This does not explain how the Pu and U-236 got into the gaseous
diffusion plants. You say that they simply provided the enriched uranium
to make the new fuel for the production reactors.
	It also does not explain how plutonium got into the DU stockpile
for military use. Presumably the latter came from the gaseous diffusion
plants (GDP).
	It seems to me that the Pu and U-236 must have come from using
uranium derived from reprocessing spent fuel in the GDPs. There was
essentially no spent fuel from commercial power plants reprocessed. I
believe the naval reactor spent fuel was reprocessed -- and then probably
re-enriched; could this be the source? Or is it possible that after the Pu
production reactors were shut down, the residual fuel went to the GDPs?
This would seem to be inefficient since this residual fuel would be
somewhat depleted and therefore less useful than natural uranium for GDP
production of enriched U.
	If these ideas are not right, can someone explain how the Pu and
U-236 got into the GDPs?

Bernard L. Cohen
Physics Dept.
University of Pittsburgh
Pittsburgh, PA 15260
Tel: (412)624-9245
Fax: (412)624-9163
e-mail: blc+@pitt.edu


On Thu, 1 Feb 2001, Stokes, James wrote:

> I may be wrong, but there appears to be a lack of understanding by some on
> how DU and low enriched U were actually processed in the production of Pu.
> A better understanding would explain some of the "facts" we have or have not
> been reading about.
> 
> "Production" reactors were used to produce Pu for defense programs
> applications. The fuel for those reactors were recycled.  As the U-235 was
> depleted, the fuel was raised back up to the appropriate enrichment by
> BLENDING woth more hoghly enriched uranium.  It was not done by sending back
> through the GDP facilities.  "Sweetner" material, of a much higher
> enrichment level, was used to restore it to fuel grade enrichment.
> 
> Seperate from that DU metal was manufactured into "target" material.  That
> materials purpose was to absorb neutrons, to become Pu.  The Pu was then
> chemically extracted, and we should all recognize that no process is 100%
> efficient.  Therefore there would be trace levels of Pu in the DU that was
> recycled.  Since U-236 is a by product of this process, the concentration of
> U-236 in the material, was an indicator of how many times it had been
> recycled.  Each "batch" of material had its own isotopic "fingerprint",
> which indicated how many times it had been recycled, and how efficient the
> chemical extraction process worked.  When the extraction process did not
> work so well, the Pu residual levels were "high", and it became the limiting
> isotope for handling purposes.  Operationally, this was called POOS
> material,(Plutonium out of specification).
> 
> The GDP in Porstmouth and Paducah did provide the "makeup" material for
> loses in the system, but the majority of the material was recycled between
> the production reactors, the chemical refinery and the metals foundry, once
> it was introduced into the production stream.
> 
> UO2 and UO3 became UF4 which became U-metal which was irradiated, PU
> extracted, and the cycle started over again.
> 
> The used of DU as a product itself was used in Hydroshots, and later the
> penetrator program.  Depending on where that DU came from, its isotopic
> profile would be different.  There were other applications of DU in defense
> programs, but I don't believe that it is publically available knowledge,
> therefore let me not discuss them.
> 
> I have no opinion about the material I stated above, but if I did, I assure
> you that it would be my opinion alone.
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