Delaved Fallout
The delayed fallout represents that fraction of radionotivity
which may etii2remain to3‘deposited out’onthe earthts
Laos,
Th asensé, theratore, at 4s an vnimown Guantaty although a me
reasonable upper Lintcan be placed onfndttttnds fron past expl
~slons. ‘Furthermore, evidence potrits‘te the fact thatbits fallout
isntfectingthenations ofand
te worldco than the country
wit
thich the
of te
tests took plac orthose
~
innediat
™
down:
wy
om
Since tha particulate detris which is Jocated in the tro eee
can be shown to be removed within 2|matter of eeeor ‘eonthgy! 4
follows that t2-the-ebsence-of_very_frsqusnt-teste, delayed 2aot
must be stored somewhere, Aircraft samplirg and balloon flights
hsve clearly established that the stratosphere is the storage
region for delayed fallout.
It can also be deduced that, since
the particles take longer than a few months to fall out of the
atinosphere, their size must be exceedingly small and it would be
estirated that they are no larger than 1 micron and probably well
below 0.1 microns in dianster,
However, despite this apparent smalle
ness in sies, we have no positive proof at this point that gravitational
settling is not important in the transfer of radioactive particles from
the stratosphere into the troposphere, and, in fact, there is the
slightest suggestion that gravitational settling may sven be inportant,
Tt 4s perhaps worthyhile at this point to review the questions which
can be asked concerning the meteorological aspécts of delayed fallout,
First, how long will the particulate debris remzin in the stratoe
sphere, and second, where will it come out of the stratosphere to be
deposited on the earth's surface,
oe
In order to mke a prediction of contamination, it is essential
to know the source of tha pollutants, The high-altitude measurements
Departsant
of Enerey
'g Office
Historian's
ARGH” ay
CL /