These more distant
times and reach the ground some distance downwind.
particles tend to have more cesium (daughter of gaseous xenon) and
stroatium (daughter of gaseous krypton) relative to other fission product
activities than do the heavier, and thus nearby, particles.
Thus,
tended through
the rather few surface explosions at Eniwetok Atoll
fractionation to result in the amounts of cesium-137 and strontium-90
deposited on the test island and nearby islands being less relative to
other fission products than the amounts produced by fission in the
nuclear explosion.
An example of this fractionation is provided by analyses of the
particles in the cloud from the La Crosse test (Nathans, 1970).
La
Crosse was a coral surface burst of about 40 kilotons on Runit Island.
The
samnte af tha radioactive clad was
2.6 hours after the event.
colleeted at
f500 meters at
The specific activity (the radioactive
with a smaller 9-micron diameter particle.
(Little variation was
found in specific activities between the smaller particle sizes ranging
between 0.5 and 13 microns.)
Specific Activity for 9 microns
Radionuclide
Specific Activity for 50 microns
strontium-90
296
promethium- 147
229
uranium
.
0.47
5
-
2 inane 0 Ctl Ba OTK MT ly EVE UO ef Ie!
factors when the largest particle of 50-microns diameter is compared
we
Maeve,
was found to increase with decreasing particle size by the following
ope a YRT. *
disentegrations per unit time and per unit weight of the particle)