EXTERNAL
<XPOSURE
A vilue of .73 Rads in tissue of interest per Roentgen measured in air at
one meter aiove the surface was used to convert exposure in air to absorbed dose
in tissue.
The source was assumed to be an exponential distribution of 13766 acy
tivity with depth in soil, typical of aged fallout (Be70).
Because of the
multidirectional nature of the source, variation of absorbed dose with depth of
organ was minimal.
Additionally, external doses were adjusted for living pat-
tern variations since the atolls present a heterogeneous exposure rate environment (Gr77).
External exposure calculations are based on figures 24, 25 and 26 which
were derived from data listed in Cr56, Sh57, Un59, and Gr77.
The area under
straight line portions of the curve was determined by
ye
te A,
n+l
(6)
where
X
=
external exposure during straight line interval, mR,
Ry =
exposure rate at the end of the interval, arn,
Ry =
exposure rate at the beginning of the interval, mkh!,
ty =
time ,;sc detonation at the end of interval, hours,
ty =
tine )osc detonation at the beginning >< interval, hours,
n
slope
=
Data fr...
nean ial
Utiri':,
of a straight Line.
1] detonations during May, June and July of 1958 (Sh57) indicated a
out deposition exponent of 18.*.
This mean value was observed at
Kon; lap, Parry and Wotho and applied to early time post detonation of
23