uniformly high in activity threughcut, the first pertion being the nost
Initially heavy fallout has been
reported to produce a peak of airtome racicactivity scen after its arrival, with the airborne activity level then decreasing. The latter
part of a fallout, though still otnervable as dust, say then add only
a small fraction to the total dese cue toth to aercsol and material
already on the ground, especially if racicactivity was mainly confined
to the larger varticles “which fell out most quickly, ff this is th
case, the total ;henomenon wouic tend loware the effect of a shorter
fallout, and the total dose would then be test estimated by acovning,
the fallout to have becn complete in some shorter “effective” tire,
such as Curve f,
The Kon,erik film badye data in Table 2.3 may be used to derive
such an effective fallout time estimate.
This procedure was followed,
ee TinealeheeiN dad Ao at alt Sila eReSa ea
intense and the belance tailing off,
The decay rate, eneryy spectzum, end aeter response discussed in Chape
ters 3 and S were used and the later dose rate measurenent on hongerik «.
(Table 2.4) was taken as a starting peint,
The upper limit of, dose
found with the outdoor badge reacings (approxisately lcu r Table 6.13)-:
sulting straight line midway between Curves a and fin Figure €,1 was
used in calewlating, the probable 12-hour cose for €ach island (Curve :
gd» Though this estimute differs appreciably from that of Ll har:
.which was originally used as an effective time in Reference 16, the
later spectrun, cecay rate, and meler response Estinales wade a le-hour
value more plausible if the film tadge readings were accepted,
Keeping a l-kcur assummticn would have resulted in a dose sone
SQ percent higher than the cutdopr tadge readings shcwed. Since the
acezracy of the film badse readings was Lelieved to be tetter than 50
percent, the l2-hcur value was therefore used, as it is more consistent
with all the other available infermation, Nevertheless, the curation
of fallout still remains the least Imoxwn parameter of the exposures,
eee
—.
This was, therefore, taken as a most pretalie tine and the re=™
fe Ba ate:
then resulted from assuming a lé-heur "effective censtant fallout®
time,