60
THE SHORTER-TERM BIOLOGICAL
HAZARDS OF A FALLOUT FIELD
THEORETICAL CALCULATIONS OF THE GAMMA RADIATION SPECTRUM, ETC.
1.00
Lon
energy
with
cum source
delivered
photons
leas than
Dy 3,8)
=
Curve A =
Fraction of
energy Ey.
scattered
from source
by
ive red
SOURCE ENERGY &; (Mev)
Fiaune 21,—Plane isotropic source, interpolation curves for elevation of $ feet above the plane.
not only the intensity of fallout at a given
location, but also the fractionation and partition of fission product source activities within
the fallout.
Moreover, even for a given set of weepon,
surface, and meterological conditions—in fact,
even after all fallout actually has been deposited
Inthis figure the dashed bars represent the
original
source spectrum
analyzed
from
a4
fallout. sample on the fourth day after the
detonation. The histogram spectrum was then
constructed following the methods discussed
here, This dose spectrum is relatively “hard’’
or energetic compared with most laboratory
in @ given instance, the nature of the fission
sources, but it is not nearly so energetic as the
This will result from both the natural decay
gammaradiations.
product gamma source will change with time.
scheme of fission products and from leaching
and weathering processes.
Despite these uncertainties in the prediction
of fallout gamma sources, some representative
picture of fallout gamma spectra may be drawn
by applying interpolation curves for plane
source geometries to fallout sample sources
analyzed in actual field experiences, This has
been done by Sondhaus[8] for a fallout sample
obtained following the “Bravo” event of
Operation CASTLE,as is seen in Figure 23.
azo
dose spectra previously presented for the initial
Although this spectrumis generally compatible with dose spectra actually surveyed in
comparable fallout fields, even further support
might be given to the analytical method if
attempts were made to correlate computer-
calculated predicted total gamma dose above
analyzed fallout fields with actual measured
data. This would be similar to the test employed in the initial gamma case, but to date
apparently it has not been attempted.
2
3
4
ENERGY (Mev)
Fioure 22.-Sample plane isotropic source, integral dose spectrum, 3 feet above the plane.
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