On the other hand, fractionation is usually much less from large
explosions at or near the surface cf the sea.
In these cases,
condensed particles are cea-water salts and water.
the
Condensation is.
late because cooling to 100°C or less is required for condensation,
and even then the small size of the dreplets allows escape of the
radioactive gases.
Much less variation then occurs in the composition
of the radioactive fallout as a function of distance from these
explosions near water.
Thus, the most frequent form of testing at
Eniwetok Atoll by means of surface barges in the lagoon just off islands
tended not to result in depletion of particular fission products in the
fallout on the local Eniwetok Islands.
In particular, cesium-137 and
strontium-90 are expected to be depleted much less in these local fallonute from raste qver or unter water comparce to lesits al cite Laud suritace,.
An example of this reduction in fractionation for barge tests
Tewa was 5 megatons, and the sample analyzed was
taken at 16,000 meters: at 2.2 hours after the event (Nathans,
Specific Activity for 8.2 microns
Specifie Activity for 41 microns
strontium-90
LL
promethium-147
13
ee eee
Radionuclide
uranium
1970).
See >
at Bikini Atoll.
Tee eee
is provided by samples of the radioactive cloud from the Tewa test
5
Leaving aside the dependence of fractionation upon particle size,
an analysis has been made of fractionation for all particle sizes.
These results also show relatively little strontium-90
_ and cesium-137 in the particles, consistent with the arguments above.
«
ee eee
1961).
ete
(Freiling,