.
Both promethium (and its progenitors) and uranium have higher
temperatures of condensation than the case for strontium and its
progenitors. Thus, the fractionation observed for strontium and
uranium are understandable, while promethium might be an example
of one sample not being representative.
The radioactivity of interest at Eniwetok Atoll is, however,
primarily local fallout rather than the cloud properties detailed
above.
The local fallout is largely from larger particles.
A
semiempirical model (Freiling, 1970) for land-surface explosions takes
this into account in predicting the local fallout compared to worldwide and intermediate-distance fallout.
(The local fraction is con-
sidered to be from particles greater than 50-microns in diameter, the
intermediate fraction from 25- to 50-microns particles, and the worldwide fraction from less than 25-micron particles.)
The percentage
of the total radioactivity of a particular radionuclude that deposits
in local fallout from these land surface bursts is estimated to be.
Radionuclides
Percentage in
Local Fallout
cesium-137 and strontium-89
10
strontium-90
15
barium-140 and lanthanum-140
25
tellerium-132.
25
zincronium-90, niobium-89,
molybdium-99 and plutonium-239
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