 
    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 
FIGHTING CHANCE: 10 feet to Survival and FIGHTING CHANCE newsletter. 
 
 
 
