eee
ual radiation from fallout will follow approximately the expressions:
y= itt?
r=f
Where:
|
ity
and
2
ty
(1.1)
kb dt = 51, (ty7*-?-t,7?-4)
exposure rate at timet
I, = exposure rate at unit time
t = time
r = exposure between times t,; andt,, where t = 10 seconds.
It is expected that the decay of the residual radiation will vary with device design.
For
example, the presence of Np” would tend to decrease the absolute value of the decay exponent
for a period of time.
4
GAMMA EXPOSURE ROENTGENS
3,
10
|
XN
\N
‘\
‘
NX
INN
102
L
FISSION PRODUCTS
NSCAPTURE TO FISSION RATIO#O5
NX
(REFERENCE 8)
aN
XN.
F
°
ein ~*~.
a
~
to
(
3
2
DISTANCE FROM GZ, 10° YARDS
Figure 1.1 Gamma exposure for 1 kt surface burst.
1.3.3 Absorption in Air. The absorption of unscattered gamma radiation in air Is exponential
with distance. From a point source of mono-energetic radiation, the variation of intensity with
distance is expressed as:
_ het?
Ip ~
(1.2)
47D2
il