SECTION3
TECHNICAL eeeae
DOSE
3.1
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DOSE CALCULATIONS
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_in order to calculate the radiation doses to personnel on Rongerik fro
Shot
Bravo fallout, the free-field radiation environment must be specified mathematically.
Further, the calculated doses are dependent on any protection or shielding that was
provided by buildings in which they stayed until they were evacuated.
(1)
Free-Field Radiation on Rongerik
Based on the available data, the free-field radiation environment on wheno be
is
ao pa ®UUaD
estimated as follows:
i
ras pec
For times greater than 48 hours after burst, the radiation decay Kiowed at -1.5
decay rate.
From the radiation intensity of ¥28 R/hr measured on Rongerik on 10
March (about 216 hours after burst), the intensity at 48 hours after burst (1, 9) iss
l4g = Jor6 (216/48)4*? = 2.67 R/hr
5
Similarly, from Ing and the radiation decay according to 177819 between 10 and
a
48 hours after detonation, the intensity after cessation of fallout through the time of
evacuation is:
ny
a
y
J,
l= Iyg (ug/tyet> - 2.67 (4g /t)el? ~ 62.7 478)
During fallout deposition, this decay applies to landed fallout particles (the
change in decay exponent at 10 hours is too early in the deposition to noticeably affect
the calculations). Thus, it is necessary to determine the fraction of time-normalized
activity (or mass, for constant specific activity) deposited with time. This deposition
is assumed to occur as a Gaussian (normal) distribution in time, reflecting a similar
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