ORNL-5388 - the Molten Salt Energy Technologies Web Site

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3.3.2. Fabrication and Handling of Denatured Fuel
J. D. Jenkins R. E. Brooksbank
Oak Ridge National Laboratory
The techniques required for fabricating and handling 233U-containing fuels encount-
ered in the denatured fuel cycle differ from those employed for 235U fuels because of the
high gamma-ray and alpha-particle activities present in the 233U fuels. Some idea of the
radiation levels that will be encountered can be deduced from recent radiation measure-
ments for a can that contains 500 g of 233U with a 232U content of 250 ppm and has been
aged 12 years since purification. The results were as follows:
Distance Radiation (mr/hr)
Contact 250,000
1 ft 20,000
3 ft 2,000
These radiation levels are equivalent to those that could be expected at the same distances
from 500 g of 233U containing % 1250 ppm 232U and aged six months, which is comparable with
233U that has undergone several cycles in a fast breeder reactor. With such high activities,
complete alpha containment of the fuel will be required, and all personnel must be protected
from the fuel with thick biological shielding (several feet of concrete or the equivalent).
This, of course, necessitates remote-handling operations, which constitutes an inherent
safeguard against the diversion of the fuel while it is being fabricated and/or handled.
The requirement for remote operation is further borne out by experience gained in
two earlier programs in which 233U-containing fuels were fabricated.
In these two pro-
grams, the "Kilorod" program' and the Light Water Breeder Reactor (LWBR) program,2
(233U,Th)02 pellets could be fabricated in glove boxes, but only because the 233U used
contained extremely low (