This report concerns the types of injuries that will be produced by a
nuclear explosion. The first topic to be covered will be scales of
destruction, or how different sizes of bombs will produce different mixes of
injuries and at what ranges. This part has a little math and geometry in it
but is only five minutes long. Don't go to sleep yet! The second topic will be
types and ranges of injuries caused by the blast portion of the bomb. This will
cover injuries caused strictly by the over-pressure, throwing the body from the
static pressure, injuries from hurled objects, and injuries from collapsing
buildings. The third topic will cover immediate burns caused by the heat from
the bomb itself and secondary burns from items ignited by the bomb. The
fourth topic is ionizing radiation, prompt (immediate) and secondary (fallout).
Many films that you see about the effects of nuclear weapons are based on
the experiance gained from Hiroshima and Nagasaki. Some people say that there
is nothing to be learned from there since today the weapons are hundreds and
thousands of times more powerful. Those films can be informative IF you
understand that a bomb is a sherical phenomenon. People are used to thinking
linearly 1+1=2, 2+2=4, etc. But spheres aren't like that. Let's look at some
math for a bit here.
One dimension. All this is, is addition, 1+1=2, 2+2=4, 4+4=8, 8+8=16, etc.
If we want to increase the distance that we can reach with a stick all we
have to do is increase the length of the stick by the same factor - in other
words to double the distance/reach you just double length, triple the distance/
reach, triple the length, ten times the distance/reach, ten times the length.
That's simple, everybody understands that! However...
Two demensions, now we are talking of area, this is multiplication now!
1x1=1, 2x2=4, 4x4=16, 8x8=64, 64x64=4,096, etc. The term "SQUARED" is used,
which is just a number multiplied by itself. 2 squared = 4, 4 squared = 16,
8 squared = 64, 64 squared is 4,096, etc. Think of this as pouring a bucket of
paint over a flat floor and figuring out how many cans of paint we need to
cover a larger circle than just a single can would cover.
If we want to increase the size of a circle that we are going to paint we
have to use the formula of a circle's area which is Area = Pi times radius
times radius or A = Pi x R x R or A = 3.1416 x R-squared. Here if we have a
circle of one unit of radius (foot, meter, yard, whatever) we need "X" amount
of paint to cover that area 3.1416 x 1 x 1 = "X". If our circle's radius
increases by a factor of 2 we need 4 times "X" amount of paint, 3.1416 x 2 x 2
= 4"X", for three times the radius we need 9 times "X" amount of paint,
3.1416 x 3 x 3 = 9"X". For ten times the radius, 100 "X" amount of paint,
3.14.16 x 10 x 10 = 100"X". That's a little more difficult.
Three dimensions! Here's where we lose people. If you are sleep prone,
I'll try to wake you after I talk about the math a bit. We are still using
multiplication, just more of it! To figure out the Volume of a box we
multiply Height times Width times Depth, or V = H x W x D. For
calculating the volume of a shpere we take four divided three times Pi times
radius times radius times radius, or Volume = 4/3 x Pi x R x R x R, or
V = 1.3333 x 3.1416 x R x R x R, or V = 4.1888888 times R cubed. Cubed is
just a number multiplied by itself twice. 1 cubed = 1x1x1 = 1, 2 cubed = 2x2x2
=8, 3 cubed = 3x3x3 = 9, 4 cubed = 4x4x4 = 64, 10 cubed = 10x10x10 = 1,000
Now that we know all of that!!! the rest is easy....
A standard rule of thumb for recalculating blast effects for various sizes of
bombs is to take the megatonage of the new bomb divide by the megatonage of
the old bomb, take the cube root of the results and multiply that times the
radius of blast effect. Example to compare a 1 KT (0.001 MT) to a 1,000 KT
(1MT) 1,000 divided by 1 = 1,000. The cube root of 1,000 is 10
(10x10x10=1,000). Therefore you can take the blast effect at X feet (or miles)
for a 1 KT and multiply that distance by 10 to get approx. the same effect for
a 1,000 KT bomb. Other common multipliers would be
Mulitplier/divider cube/cube root 1 KT multiplier 1 MT divider
2 2x2x2=8 8 KT 125 KT (0.125MT)
3 3x3x3=27 27 KT 37 KT
4 4x4x4=64 64 KT 16 KT
5 5x5x5=125 125 KT 8 KT
6 6x6x6=216 216 KT 4 KT
7 7x7x7=343 343 KT 3 KT
8 8x8x8=512 512 KT 2 KT
9 9x9x9=729 729 KT 1 1/3 KT
10 10x10x10=1,000 1,000 KT (1 MT) 1 KT
So this shows that if you want to double the damage distance for a given size
of bomb you need to increase the power by a factor of 8. If you want to double
that distance again you need a bomb that is 8x8 or 64 times as powerful. This
is why you can get the same amount of damage done with 10-40 KT bombs spread
out as you can with a 1,000 KT (1 MT) bomb. So if we look at Hiroshima with
20KT and say okay what will a 1MT (1,000KT) bomb do? Well 1,000/20 = 50. Now
then, what times what times what = 50, well 3.7 cubed is 50.653 so an effect
one mile from GZ at Hiroshima will be the same effect at 3.7 miles for a 1MT.
Now this is for blast effects not heat effects, we'll cover those later.
Okay any questions?
All right, that's the end of the math, you can wake up again!
Okay let's talk about blast injuries. To avoid confusion we need to talk
about overpressure (static-pressure) and dynamic pressure. When you think
about overpressure, think about a barometer, normal air pressure is about
15 P.S.I. Overpressure is simply the air pressure in excess of the normal
atmospheric pressure. Overpressure is what would cause an empty sealed can to
be crushed on all sides. Dynamic pressure is a wind. Dynamic pressure is the
figure that we use to calculate the horsepower of a sail on a sailboat. Damage
is caused by wind resistance. The dynamic pressure is proportional to the
square of the wind speed and to the density of the air behind the shock front.
In a nuclear blast the air density can be quite high and this is why just
looking at the wind speed alone doesn't give the entire story. Also, the
duration of the dynamic pressure comes into effect. Dynamic pressure is what
would cause an empty sealed can to be blown into the next county. Think about
a sheet of plywood placed perpendicular or parallel to a blast front. Ignoring
the time it takes for the overpressure to get from the front to the back of
the plywood, the overpressure shouldn't do much damage. Contrast that to the
same sheet hit broadsides or sideways by dynamic pressure!
A further note on duration. Many things can take great stresses over very
short periods of time. Example, a fast blow fuse can pass ten times its
amperage rating for a fraction of a second. In overpressure this is why lung
injuries occur at pressures that would not cause harm if the pressure were for
only a second or two.
Ok, injuries in humans caused by the blast. Now when I talk about injuries
from a specific effect I am talking about just that single effect. In real
life, a victim might have some lung damage, some broken bones, 2nd degree
burns, and some blood loss from flying glass shards. Each one seperately might
not be lethal, but in combination they might be.
Let's start with overpressure. Overpressure is associated with ear and lung
damage from fast-rising, long duration pressure pulses. If it were a slow
rising pulse the body can equalize, as in scuba-diving. If it were short
duration the parts could stand greater stress. You won't die from eardrum
rupture, but it does reduce your abiltiies! 5 Pounds per Square Inch is where
eardrum rupture starts. There is a great deal of variation in suscetabilty to
damage. The very old are most susceptable. 50% of population rupture occurs
at around 15-20 PSI for over 20 years old and around 30-35 PSI for under 20
years old. Again, there is a wide individual variance here. Also, some
eardrum will spontaneously heal with only slight or partial hearing loss.
Lung damage begins at 12 (8-15) PSI. Severe lung damage occurs at 25 (20-30)
PSI. Lethality begins at 40 (30-50) PSI, 50% lethal at 62 (50-75) PSI and
100% lethal 92 (75-115) PSI. P.549 "Persons who spontaneously survive for 24
to 48 hours in the absence of treatment, complications, or other injury usually
recover and show little remaining lung hemmorrhage after 7 to 10 days. In very
severe injuries under treatment, recurring lung hemorrhage has been reported as
long as 5 to 10 days after injury.
Overpressure 20KT 200KT 2MT 20MT
1 PSI 3.5 miles 7.5 miles 16.5 miles 36 miles
2 PSI 2.1 4.6 10 21
5 PSI 1.1 2.5 5.4 12
40 PSI .28 .6 1.3 2.8
62 PSI .23 .5 1 2.3
92 PSI .19 .4 .9 1.9
Any questions on overpressure?
Dynamic pressure injuries are typically measured in the speed (feet/second)
at which a human body is thrown against something hard. Injuries here are
cuncussion, skull, heel, foot, legs, and arm fractures. There is a great deal
of variability in these injuries. A threshold of injuries standing up might
occur at 10-12 ft/sec with fractures at 13-16 and while sitting the threshold
may be 15-26 ft/sec. Skull fractures - "safe" 10 ft/sec, threshold 13, 50% at
18 ft/sec and 100% at 23. From total body impact - mostly "safe" 10 ft/sec.,
1% fatal 21 ft/sec, 50% 54 ft/sec., and near 100% 138 ft/sec. These are
assuming that the body is hurled perpendicular against a hard object.
Dynamic pressure 20KT 200KT 2MT 20MT
10 ft/sec 1.2 miles 3.0 miles 7.4 miles 17 miles
21 ft/sec .9 2.4 6 14
54 ft/sec .6 1.7 4 9.5
138 ft/sec .3 .9 2.4 5.5
Well what about being blasted in an open field? You can be tumbled to death.
There are no good figures on this since there is no actual data and only
animal experiments have been used. The best guess is that 1% non-fatal injury
would occur at 30 ft/sec. and 50% injured at 75 ft/sec. We really don't know.
Any questions on dynamic pressure?
Many casualties and deaths will occur from building collaspe. A typical
house is calculated to have these characteristics. 50 PSI = 100% certian dead,
20 PSI = 50% killed - 35% trapped - 5% untrapped but seriously injured, 10 PSI
= 10% killed - 35% trapped - 6% untrapped but seriously injured. 5 PSI = 1%
killed - 10% trapped - 6% untrapped but seriously injured. Now those are from
the British home office and for overpressure ONLY. I feel they are whistling
in the dark, but perhaps they figure that a British house has stronger and
heavier sidewalls if it uses structural brick or stone rather than using
brick as a decorative siding as in America.
Injuries from heat can be burns from the flash or secondary fires. Flash
burns and fires are HIGHLY variable due to landscape interference, dust and
moisture in the air, and topography. While there is some damage from
reflected light and heat, most of the damage is from line of sight to the
point of explosion. Another complicating factor in heat related injuries is
the speed at which the bomb releases its heat and how well the object or person
relfects, absorbs or disipates the heat. Smaller bombs dump their heat
quicker since there is less heat to dump. See chart.
Percentage of
heat released 20 KT 200 KT 2 MT 20 MT
20% .16 seconds .4 seconds 1.15 seconds 3 seconds
50% .35 .95 2.2 7
70% .8 2.2 6 15
Whites reflect heat while blacks, blues, and purples absorb heat. Also, even
though the object is stationary and doesn't move (by say failing to the ground
and rolling) it can still release heat while more is coming in. That is why
just looking at the calories per square centimeter at a certian distance does
not tell the whole story. Examples, see P. 564 and P. 565. A third degree burn
from a 10 MT ranges from 10.5 to 12.5 Calories per Square Centimeter depending
on skin color and a 3rd degree from a 20 KT ranges from 6 to 8 Cal/SqCm. For
those two bomb sizes 2nd degree burns range from 6.5 to 8.25 and 4 to 5 CSC.
For 1st degree burns 3.5 to 4.5 and 2 to 2.5 CSC for 10MT and 20 KT. With the
range of needed CSC linear for bombs in between those two sizes.
Degree of burn 20KT 200 KT 2 MT 20 MT
First 2.2 miles 6.2 miles 16 miles 35 miles
Second 1.7 4.8 12.5 30
Third 1.3 3.8 10.5 26.5
SIZE 35 KT 1.4 MT 20 MT
Paper bag burns 10 Cal/SqCm 13 Cal/SqCm 20 CSC
New blue jeans burn 12 27 44
white cotton shirt burns 32 48 85
Here is what range you would get from various bombs
Cal/SqCm 20 KT 200 KT 2 MT 20 MT
1 3.4 miles 9 miles 22 miles
5 1.7 5 13 35
10 1.2 3.6 10.5 29
20 .85 2.6 8 23
50 .55 1.7 5.4 17
100 .4 1.2 4 13
Please remember these are assuming a clear sky, no rain, no dust, no haze,
no smog, etc.
Injuries to eyes fall into two catagories. Permanent (retnal burns) and
temporary flashblindness. You of course can suffer from both. Flashblindness
is just like staring into a flashbulb, useful vision is lost for several
seconds to several minutes. A retnal burn causes blindness on the point of
the retina where the flash is seen. There is an emense variation here
depending again on clarity of sky and also whether the pupil is wide open at
night or fairly closed from mid-day sun. See page 571-574 for details.
There is one other eye "problem" that should be mentioned, Keratitis which is
inflamation of the cornea. The symptoms are pain caused by light, a sensation
that a foreign body is in the eye, lachrymation (unnatural tears), and redness.
These symptoms lasted from a few hours to several days. At Hiroshima only 4%
of those standing in the open within 1.25 miles of GZ suffered keratitis within
24 hours. An additional 1.5% had symptoms up to one month.
Wake up! I'm almost done.
The last and FINAL topic is radiation. Immediate radiation from the the
blast is significant only from smaller bombs since the deadly other effects
outdistance the radiation effects in larger bombs.
REMS 20 KT 200 KT 2 MT 20 MT
1 1.7 miles 2.1 miles 2.8 miles 4 miles
10 1.4 1.8 2.4 3.6
100 1.05 1.45 2.1 3.2
400 .9 1.3 1.8 3
1,000 .8 1.15 1.7 2.8
10,000 .54 .85 1.3 2.3
100,000 .32 .56 1.8 1.68
1,000,000 .16 .33 .59 .97
The reason that 10,000 REMS and higher is included in this chart is that it
is possible to build shelters to withstand 200 PSI overpressure. These
are usually buried enough to have Protection Factors of over 1 million. See
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