[ RadSafe ] Graphite SWAG Answer - Helium on tubine? - thori um cycle

Nardi, A. Joseph nardiaj at westinghouse.com
Tue Nov 15 17:01:17 CST 2005

It is not accurate to assume that the Th-232/U-233 fuel cycle is nuclear
proliferation resistant.  Here are a couple of points for consideration:

1) I have never seen an analysis of the potential to make a weapon from
U-233 but it would seem to be similar to high enriched uranium.  U-233 is
fissile and most probably could be used to make a weapon but has not been
available and has higher associated dose rates.  In the Th-232/U-233 fuel
cycle it would be possible to chemically separate the Th and U and therefore
have U-233 in a pure form.  This would be similar to extracting Pu from a
low enriched uranium fuel cycle.  You could not count on a "once through"
fuel cycle because that loses the entire point of Th-232/U-233 fuel cycle.  

2) It is not possible to startup the Th-232/U-233 fuel cycle without a
fissile component such as high enriched uranium or Pu.  Th-232 can not be
made to go critical as you can do with natural uranium.  So the first core
would have to be fueled with Th-232/U-235 or Th-232/Pu to start the
generation of U-233.

3) Most Th-232/U-233 fuel cycles are "burners" rather than "breeders" so you
would have to continue to feed fissile material such as high enriched
uranium or Pu to make up for net consumption of fissile material in the fuel
cycle.  There have been some attempts at developing thermal breeder reactors
for the Th-232/U-233 fuel cycle but I understand the breeding ratio is very
low so it would take a long time to breed enough U-233 to start the next

A. Joseph Nardi
Westinghouse Electric Company
P.O. Box 355
Pittsburgh, PA 15230
Phone - 412-374-4652
FAX - 412-374-3832
email - nardiaj at westinghouse.com


From: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl] On Behalf
Of JGinniver at aol.com
Sent: Saturday, November 12, 2005 2:23 PM
To: hflong at pacbell.net
Cc: radsafe at radlab.nl
Subject: Re: [ RadSafe ] Graphite SWAG Answer - Helium on tubine?


  As  far 
as I know the best hope for a fuel cycle that can't be used to produce  
nuclear weapons is the Thorium to Uranium-233 fuel cycle.  I believe that
it was 
only India that has worked on this option in recent years.

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