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FALLOUT CHARACTERISTICS
In order to ealontate a total gaosa dose micelved by an individual in an araa where dyso rate was peasured at a given tine, a value
fur the rate of chaara of radiathen intensity during the exposure
ct
perled mist te assuurl. fhe Latter quantity has often buen aj-proxtwok using
he wall known aged mar (tthe) cucay daw, in this case
mated
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nS htowhn that larse ancunts of ‘pe 39 and we wore to be
expectid in the talloit of tha 1b March shot, making its “early dacay
characteristivs as well us its energy spectrin somenhat diffurent fron
those of prevtous dutuitions, it was therefove declded, that the
value of decay rate assuced to exist during the exposures should be
based, as far as puscible, upon experimental data fran this test,
a
Unforumataly, no decay rates were followed closely in any of the
imsediate areas whers the exposures occuurred, and it is knewn that the
radicchanical cunposition and dacay rate of the fission 3 roduct mixture
taAans
ntan
usually vary both with place end time, Howsever, §cark ' ‘ dneay
TaALSS
in
the Bikini layoon itself had been measured in a series of fallout
samples taken at olber joints nearer the site of the detonation
(heferernce 5).
Since these valuos were the best data available, they
were used in the calculations and were assumed to hold fcr the fallout
on each of the islands,
The early samples showed a consistent pattern among various loca-
tions and a decay exponent (n) of tetween 0,3 and 0.9 in Equation 3.1,
A= Ay ( t/t$1)" n
where:
(3.1)
A-= activity (d/m) at time t,
This decay exponent (n) was found evperinentally to fit the data
for the seriod H+ 5 to H+ 50 heurs,
The ebserved values are given
in Reference 5,
3.2
CALCULATED DECAY RATES
These decay rates were 5 poypered
with, calculated values kased on
te
‘Ot tha fallout mixture, The calcul
the presence of Npt7? and ?’
ticns were made on the arsu “tion that the relative abundance of N
t
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