may be made merely by superimposing
Graph 4 on Graph 3; the point where the
curves become tangential is the point of
meximuin effect to be expected from doses
accumulated from fallout. It is not intended to imply that no further radiation
damzre is received from exposure after
of the total dose accrues froin fallout dur-
ing the first part of the exposure period.
This more rapid rate of delivery might increase the percentage of irreparable dainage to some extent.
On the other hand,
a greater proportion of the biologicai dainare would occur early in the exposure
C
ral
(MILLIROENTGENS PER HOUR)
GAMMA DOSE RATES (THREE FLET ASOVE GROUND)
=
‘
eof
Sa
ae
.
.
e
a
.
.
™.
Re
.
1 6 OD POs = seme ff
a]
i
{
{tt
j
jt
10
wo
TIME AFTER DETONATION FALLOUT OCCURS (HOURS)
Graph 5. Approximate gamma dose rates at time of fallout te produce an estimated effective biological dose of 1 r for personnel continuing to live normally in a
’ contaminated area. See text for assumptions.
that time. Rather, the analysis does indicate that if the accumulated dose from
fallout up to the time of tangency is not
sufficient to produce death or radiation
sickness, than (a) the rate of repair (for the
reparable portion of the dose received) will
exceed the rate of exposure thereafter,
and, of course, (6) the irreparable fraction
of the total dose for the duration of the
fallout will be insufficient to produce these
whole-body effects. It is recognized that
the rates of dose accumulation as calculated by the two methods (Graphs 3 and 4)
are not identical, since a larger proportion
period, allowing a longer time for the reparable factor to operate before the curves
become tangential. The radiation status
for the reparable fraction of the damagets
thus better at the time of tangency. Until more definitive data are obtained, this
analysis may serve to approximate the
biological repair factor.
Graph5 incorporates into a single curve
the major effects due to weathering, shiclding, and biological repair. The radiation
dose arrived at by these calculations is
called the ‘effective biological dose.”’ As
in the previous graph, the accumulated
eta et aMll idl, da tOery
-
ry
Lo
~ Apei 1085
Corvon M. Dunnixa
.
590