D
When an atomic bomb is deto-
nated at a high altitude, as it was
in Japan, so as tO cause maximum
blast damage to a city, the hazard
due to radioactivity on the ground
after the explosion is small.
Tests at Low Altitudes
Atomic
bombs
were
altitude, results in the deposition
of contaminated debris at some distance away. In addition, much of
the dust is carried aloft into the
atomic
cloud,
but
it
eventually
settles to the earth as the fall-out,
exploded
experimentally at low altitudes at
Alamogordo and Eniwetok. Radio-
active contamination of the ground
was Many times greater than for
the high altitude bursts, due to
the fact that the Ball of Fire
touched the earth’s surface. The
radioactivity near the center of
the explosion resulted partly from
condensation of fission products
upon contact with the ground, and
partly from radioactivity induced
by neutrons.
The approximate radiation dosage rates, in roentgens per hour,
measured on the ground at Alamogordo one hour after the detonation had taken place at a height
of 100 feet was 8,000 r at ground
zero, 5,000 r at a distance of 300
feet from ground zero, 600 r at
600 feet, 150 r at 900 feet, 30 r at
1.200, 10 r at 1,500 feet. 5 at 2,250,
0.3 r at 3,000 and 0.07 at 3,750 feet.
It can thus be seen
in the formation of a crater, which
accompanies an air burst at low
that near
after picking up fission product
particles, to contaminate areas
much further from the center of
the explosion,
After the Alamogordo test, for
example, high concentrations of
radioactivity were detected on the
ground several miles north and
east of the site of the explosion.
The integrated dose was, however,
not dangerous to human life.
Dust’s Effects on Animals
A number of cattle, about ten
to fifteen miles from the Alamogordo explosion, were inadvertently exposed to the radioactive dust
from the fall-out. In the course of
a few weeks, loss of hair and blisterlike lesions were apparent. The
latter soon healed, however, and
the
hair,
originally
red,
grew
again, although it was white or
gray.
Continued observation of the
animals has shown that the cows
so
concentrate
mineral
elements
to descend at a distance from the
explosion. However, although the
plankton and algae, absorb the
nutritive salts from the water, and
ation intensity may be correspondingly greater at small distances
from the bomb burst.
large aquatic forms, namely. fish,
which directly or indirectly consume the simple plants,
How Radiological War Works
The possibility exists of contaminating persons, objects or areas
with radioactive materials not pro-
cumstances arise in water environments;
the simple plants, i.e.,
they are then accumulated in the
Radioactivity In Water
materials, the latter are
concen-
trated by the fish in the same
manner and for the same length of
time as are the stable forms of the
corresponding elements, If the fish
die, the radioactive istopes are not
lost, but they return to the water,
as do the stable isotopes, to take
part once again in the life cycle.
Because of the landlocked nature
of the Bikini lagoon there is evidently little or no outward migra-
tion of the larger aquatic organisms, so that there is no appreciable tendency for the radioactivity to spread. However, due to the
behavior of the anadromous migratory fishes, namely, salmon, shad,
etc., which feed in the sea and then
uninhabitable because of the radiculations show that a vehicle trav-
fects of the radiation, other than
might be some distribution of
radioactivity in other cases following an underwater atomic explo-
Of various types of atomic ex-
and its effect would depend greatly
jected to a low altitude airburst,
small compared with the damage
area due to the bomb, would be
ation
hazard.
Nevertheless,
there was mo evidence of any ef-
cal-
the graying of the hair.
eling at a moderately high speed
could
cross
the
contaminated
or fell back into the lagoon in the
form of the radioactive base surge
and rain. The total dosage due to
the base surge and contamination
from the underwater burst ranged
from 8,000 r down to a 100 rtoa
distance of about four and onehalf miles.
terial into the system. Masks such
as used in chemical warfare pro-
an underwater burst of an atomic
The disturbance of large quan-
spread over a large area due to
the action of marine life. It is well
There is the possibility that after
bomb, the radioactivity might be
tities of earth and other material
in
guano,
there
sion. The extent of such dispersion
The possibility must also be considered of an underwater explosion
So near to the shore that significant amounts of the fall-out and
the base surge will reach the ad-
or more before it would be safe to
tection are suitable for this purpose.
sea
degree of radioactive contamina-
tion. It is estimated that almost
all of the fission-product activity
either remained in the water immediately following the detonation,
to prevent entry of the active ma-
the
on circumstances and appears difficult to estimate.
Bikini produced by far the greatest
walk across the area; but to stay
for any length of time would, of
course, be out of the question, unless proper shielding were available. The great amount of radioactive dust remaining in the air
after
a
low-altitude
explosion
would require special precautions
of
Plosion the underwater burst at
fround about 15 minutes after the
explosion without the occupants
being greatly harmed.
It would probably be six hours
migrate upstream to die, or of
birds that concentrate the minerals
This deliberate use of radioactive
isotopes as an offensive military
weapon is known as radiological
warfare, The materials to be used
can be either fission products, ob-
tained in a nuclear reactor, or arti-
ficially made radioactive isotopes,
produced from stable elements by
exposing them to neutron bombardment. Such warfare would
present many difficulties, both in
the production of the materials
and in delivering them to the target. Perhaps its most important
application would be its psychologica] effect as a mystery weapon.
If gamma ray emitters were to
be used as radioiogical warfare
agents, and these seem to be the
only ones likely to be effective, the
problem would arise of shielding
personne! from the radiations during manufacture, storage and delivery of the weapon. The use of
adequate shields, presumably of
concrete, iron or lead, would add
greatly to the weight of the munition and would complicate the
mechanism of dissemination on the
target. The uniform distribution of
a relatively smal] amount of material over a large area would it-
self present a difficult probiem,
the solution of which might nullify
the advantage of compactness.
While it is impossible to predict,
as in the case of chemical warfare,
whether radiological warfare will
jacent land areas, and possibly affect dock facilities) warehouses,
etc.
be used or not, it is necessary to
understand and be prepared forit.
Only in the event of being unprepared are the consequences
likely to be as serious as the de-
The general consensus at the
present time is that the size of an
area highly contaminated by an
underground explosion would be
less than in the case of an underwater burst. One reason is that the
struction
bomb.
density of the soil is greater than
known that land plants absorb and
34
area covered may be less, the radi-
duced in an atomic explosion.
In water containing radioactive
have produced normal calves, irrespective of whether they were
mated with buils which had, or
had not, been exposed to the radioactive dust. By the end of 1949
the explosion center an area sub-
that of water and 80 a smaller
mass would be thrown into the air
from the soil, and that these are
further concentrated in animals
feeding on the plants. Similar cir-
36
caused
by
an
atomic