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introduce time, cost and visibility considerations. These factors would force a
3-36
trade-off between the desirability of utilizing material from the denatured fuel cycle and
obtaining fissile material by some other means, such as isotopically enriching natural
uranium or producing plutonium in a research reactor.
A subnational group, on the other hand, would not in general possess the requisite
technological capability. In addition, while a nation could, if they chose to, carry out
these processes overtly, a subnational group would have to function covertly.
radiation barrier interposed by the self-spiking effect of the 232U contaminant in the de-
natured fuel would contribute in some measure to the safeguardability of the denatured
fuel cycle insofar as the subnational threat is concerned.
Thus the
The degree of protection provided by the self-spiking of denatured fuel varies accord-
ing to the radiation level.
tion and the time elapsed after the decay daughters have been chemically separated.
indicated in other sections of this chapter, in denatured fuel the expected concentrations
of 232U in uranium are expected to range from $100 to 300 ppm for thermal systems up to
%1600 ppm for recycled fast reactor fuel. It should be noted that if the latter denatured
fuel (typically 10-20% 233U in 238U) is processed in an enrichment facility to obtain highly
enriched (~90%) uranium, the resulting material would have a 232U content that is propor-
tionally higher, in this case $7000 to 8000 ppm maximum.
The radiation level in turn depends on both the 232U concentra-
Table 3.3-9 shows the radiation levels to be expected from various concentrations
of 232U at a number of times after the uranium has been separated from other elements in
a chemical processing plant. For a 5-kg sphere of 233U with 5000 ppm of 232U the radia-
tion level 232 days after chemical separation is 67 r per hour at l m. The highest
level of deterrence, of course, is provided when the radiation level is incapacitatfng.
Table 3.3-10 describes the effects on individuals of various total body doses of gamma
rays. Complete incapacitation requires at least 10,000 rem. Beginning at about 5000 rem
the dose is sufficient to cause death within about 48 hr. In the 1000-rem range, death
is practically certain within a week or two. A dose causing 50% of those exposed to die
within several weeks (an LD-50) is around 500 rem. Below 100 rem it is unlikely that any
side effects will appear in the short term but delayed effects may occur in the long term.
In general, the gamma-ray total dose levels required to ensure that an individual is dis-
abled within an hour or so are at least on the order of a magnitude higher than those
likely to'cause e v e W death. There may be individuals who are willing to accept doses
in excess of several hundred rem and thus eventually sacrifice their lives. As indicated
above, to stop persons of suicidal dedication from completing the operations would require
doses in the 10,000-rem range. Apart from the dedicated few, however, most individuals
would be deterred by the prospect of long-term effects from 100-rem levels. However, it
is also important to note that the individuals involved in the actual physical operations
may not be informed as to the presence of or the effects of the radiation field.
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