vee
ee ee el ee
i Se °
Gasmta RADIATION Exposures FROM FaLLout
Vol. 66
Neither the exact time of winds and rains
nor the precise extent of dose-rate reduction can be predicted. These two param-
ct crs
are
°bvious!
. y
uanta
que
.
events to
which a straight line function may be as:
Sor
only by the process of gencraliza
cribed
tion, as in Graph 2. The following esti.
cantle
mates
nay be proposed:: For the first week
followingfallout, the measured gamma ac-
.
ua
.
4
a ee ar
1009
=
Taste I:
EstimaTeD ATTENUATION FACTORS OP
Gamma Doss RATES FROM FALLOUT
Approximate
Structure
Frame House
;
First Goon cen veseeees beeveee
Basement
oaseeee
(aide) tt!
Basement (center)........
Muttistory Reinforced Conercte
Loweriloors (away from windows).
Dosenent eons?
Shelter (cquivalent of 3 fect of earth)
4
*.
CC
Factor
2
10
+10
19
~1,090
~1,000
|
~
Gamma dose rate readings at
i
three feet above the ground
8
587
\
”
an island of Rongelap
4
iu
a
® 100 |
li
—
2
=
>
,
—_—
is
“es
F
e
3
SL
ww
ww
Zuw
8
1b
C
ef:
=
pa
o
s
fF
-q
‘
a
iy
a
on
10
on
on
100
rey
teri
1000
DAYS AFTER OETONATION
Graph 2.
Gamma dose ratcs on the island of Rongelap following detonation of
March 1, 1954.
tivity is assumed to decay according to
(t)~'?, for the second week (t)~!:*, and for
the third week and thereafter. (t)7'“
Justification for such values lies not in the
high probability that they will occur at
these times but rather in the necessity of
generalizing (probably conservatively) in
advance, so that some estimate of the
parameter of weathering may be incorporated into evaluations of possible future
contamination.
Field measurcments, as well as calcula-
tions, have indicated the attenuation of
gamma dose rates to be expected from the
shielding afforded by various structures.
Obviously, there will be wide differences
in this respect, depending upon the type
andsize of the structures; Table I gives
some rough estimates of this factor of
shielding.
For the moment, let us con-
sider a situation in which no special evasive
measures arc taken and people continue to
live normally in the contaminated environ-
ment.
Great variation in the amount of