fellows mevrailine indceors vas 1/5 that fourd oubeide},
Such a
shielding factor is in agrecment with thet proposed by the TM es an
averages for Western type structures (10).
4n additional feetor hss
besn suggested by this body to account for usetheringe which reduces
the dose because of leaching, washorf, and other mschenisms which
reduce the activity present.
Over the period 1957 to 1959 no directs
evidence has been found at this laboratory for a downverd movamant
of Cel?7 an soil, nor has it been fornd for any of the other isotopes
mentioned,
Therefore, for this period, no factor has been included
for weathering.
A unique situation exists at the prssent tine for the study
of fallout mechanisms.
Testing of nuciear weapons has stopped, and
there is no further injection of fission debris into the stratcspheric
resevoir, so that it should now be possible to obtain values for fallout
rate and stratosphsric storage time,
Furthermore, since no new activity
is being produced, there is some justification for hoping that future
leveig of radicactivity end radiation may be predictsd within
reasonable limits.
To this end monthly soil samples have been collacted
at Avgonme sinee March 1959, and from these samples fallout rates for
eech rediocisotope mentioned have been determined.
Interpretation is
complicated by the fact that a portion of the fallont at Argonne coms
from testa conducted by the US and UK in the Pacifie srea and a portion
from Russian testa carried out in the far North.
The stratospheric
storage times and consequentiy the fallout rates appear to be substantially
different for debris coming initially from these two loeebions (11,12).
pos pacatve?