EVENT AND
1.2
DESCRIPTION OF EXPOSED
-
GROUPS
oO
carried out, nor was its operating condition
Whole Body Gamma Doses
known to be satisfactory under the emergency
condition prevailing at the time of use. For
these reasons the later readings, which were
higher than the early survey by an average of
50 percent when corrected to the same times,
were used in computing the doses listed. The
instruments used for the later measurements
“were calibrated just prior to the surveys.
Tre Estimatrep Vatters of external dose given
in Table 1.1 were calculated from readings of
radiation field survey instruments.* Averages
of a numberof dose rate measurements on each
island at a given time were used. The readIngs were taken in air, approximately threc
feet above ground, several days after the inhab30
iol
ORIGINAL SOURCE
SPECTRUM
INFINITE PLANE, SIN AIR
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ENERGY (KEV)
Fictre 1.2—Distribwtion of inherent energics ef gaunng radrafion from mired
fission products, and histugram of degroded cnergies produced by Contutan
scattering at level of infinite plane 3 feet in cir above untformly-drstribuied
Hants were evacuated. DBefore this time, adequate surveys with well calibrated instriments
had not been possible, although readin,rs had
been taken with a single survey meter at the
tine
of
However,
*Arniv Nuva eatalar ANSP DIE 29,
—
_
evacuation.
prefminary
calibration of this instrument had not been
~
ee ee
fission products ficid.
S002 1b3
1.21
Characteristics of the Gamma Radtation
The fallout material, when deposited on the
ground, formed a large planar source of radiation. The energydistribution of the radiation
reaching an exposed individual was infinenced
by its passage through the intervening ar, A
knowledse of the energy spectrum of the ra-