BENTEHAL
Similarly, with 3-hr evacuation it is found that approximately 37 percent of the
population who are not killed by blast and thermaleffects would be exposed to 250 r (0.05
lethality) and a few more than that exposed to 500 r (0.88 lethality).
Figure 31 shows some actual cz for an attack with a cep of 12,000 m. The main popu-
lation centers of Baltimore and Washington happen to remain almost untouched by primary
effects in this particular attack, but the areas in which large numbers of evacuees would
be located have radiation levels up to 3000 r in addition to suffering heavy damage from
primary blast and thermaleffects. It would seem clear that under these conditions (large
CEP) up to 50 percent lethalities in the evacuated population could be expected.
Figure 34 summarizes the revised estimates for an attack with a cer of 4000 m. It is
clear that for realistic attack assumptions (multiweapon large-cEp attacks involving fallout) undergroundshelter is the preferable civil defense tactic.
100
80 L-
zOo9
T
Best available shelter
\
60b
3-hr evacuation
Ww
o
w
~
=
< 40
w
a
Underground shelter
20 -
0
—
|
|
1
2
_|j
3
4
t0-MT WEAPONS
Fig. 34 — Percentage Washington Resident Population Killed by Direct Effects
plus Fallout from One to Four 10-Mt Weapons, cep 4000 m
It is possible for a target population to evacuate from anticipated attack only to find
itself in the path of fallout from an adjacent target. Figure 35 showsfallout-contaminated
areas for a mock attack on 5 Aug 55 in which no weapons were actually exploded on
the Washington target but were on a large numberof nearby targets. It will be noted that
a fallout-free proposed reception area exists only toward the southwest, 25 miles distant;
most of the proposed reception areas received a cumulative 2-day dose ranging up to 2200 r.
EFFECT OF WIDESPREAD ATTACK"
Since an attack on Washington and Baltimore alone markedly reduced the effectiveness of mass evacuation, the effectiveness of mass evacuation under a widespread attack
on many targets was considered.
48
ORO-R-17 (App B)