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3.3.5. Deterrence .Value of 232U Contamination in Denatured Fuel
C. M. Newstead
Brookhaven National Laboratory
The preceding sections have emphasized that unless 232U i s isotopically separated
from 233U, both it and its daughter products will always exist as a contaminant of the
fissile fuel. And since as 232U decays to stable 208Pb ithe daughter products emit several
high-intensity gamma rays (see Fig. 3.0-l), all 23% fuel, except that which has undergone
recent purification, will be highly radioactive. While the gama rays, and to a lesser
extent the decay alpha and beta particles and the neutrons from a,n reactions, will intro-
duce complications into the fuel cycle, they will ais0 serve as a deterrent to the seizure
of the fuel and its subsequent use in the fabrication of a clandestine nuclear explosive.
Consider, for example, the steps that would have to be followed in producing and using such
a device:
1. Diverting or seizing the fissile material (as reactor fuel elements or as bulk
material).
2. a. Chemically reprocessing the spent fuel to separate out the bred fissile plu-
tonium (or 233Pa) or
b. Isotopically enriching the fresh fuel or bulk material to increase the 233U con-
centration in uranium sufficiently for its use in a weapon.
3. Fabricating the fissile material into a configuration suitable for an explosive
device.
4. Arming and delivering the device.
As indicated, at Step 2 a decision must be made as to which fissile material is to be
employed, 239Pu o r 233U.
require a chemical separation capability analogous to that required for current LEU spent
fuel; however, the quantity of spent denatured fuel (i.e., kilograms of heavy metal) that
would have to be processed to obtain a sufficient amount of 239Pu would be increased by a
factor of 2 to 3 over the amount of LEU fuel that would have to be processed.
for some reactor systems, the quaZity (i,e., the fraction of the material which is fissile)
of the plutonium recovered from denatured fuel would be somewhat degraded relative to the
LEU cycle.
Extracting the plutonium present in spent denatured fuel would
Moreover,
The selection of 233U as the weapons fissile material means, of course, that the
material being processed through all the operations listed above would be radioactive. While
both national and subnational groups would be inhibited to some degree by the radiation
field, it is clear that a national group would be more likely to have the resources and
technological base necessary to overcome the radiation hazard via remote hand1 ing, shielding,
and various cleanup techniques.
Thus, the radiation field due to the 232U contamination
would be effective in limiting proliferation by a nation to the extent that it would com-
plicate the procedures which the nation would have to follow in employing this path and