Wednesday, 7 August 2013
Effects of Nuclear Weapons
Effects
of Nuclear Weapons Detonations
Because of the tremendous amount of
energy released in a nuclear detonation, temperatures of tens of millions of
degrees C develop in the immediate area of a nuclear detonation (contrast this
with the few thousand degrees of a conventional explosion). This compares with
the temperature inside the core of the Sun. At these temperatures, every thing
near ground-zero vaporizes (from a few hundred meters in 15 kiloton weapons to
more than a kilometer in multimegaton weapons). The remaining gases of the
weapon, surrounding air and other material form a fireball.
The fireball begins to grow rapidly
and rise like a balloon. As the fireball rises and subsequently expands as it
cools, it gives the appearance of the familiar mushroom cloud. The vaporized
debris, contaminated by radioactivity, falls over a vast area after the
explosion subsides – creating a radioactive deadly fallout with long-term
effects.
Figure 1 : Illustration of blast effects for a15 kiloton explosion.
Zones 1 and 2 correspond to the "killing field" where the fatalities
are universal.
Because of the very high
temperatures and pressures at ground zero, the gaseous residues of the
explosion move outward. The effect of these high pressures is to create a blast
wave traveling several times faster than sound. A 15 kiloton weapon creates
pressure created in excess of 10 Psi (pounds per square inch) with wind speeds
in excess of 800 km per hour up to about a 1.2 km radius. Most buildings are
demolished and there will be almost no survivors (much larger strategic nuclear
weapons will greatly extend this radius of destruction).
Beyond this distance, and up to
about 2.5 km the pressure gradually drops to 3 Psi and the wind speed comes
down to about 150 km per hour as in a severe cyclonic storm. There will be
injuries on a large scale and some fatalities. Beyond this zone of fatalities,
the pressure drops to less than 1 Psi, enough to shatter windows and cause serious
injuries. It is the high speed combined with high pressures which causes the
most mechanical damage in a nuclear explosion. Human beings are quite resistant
to pressure, but cannot withstand being thrown against hard objects nor to
buildings falling upon them.
Blast effects are most carefully
considered by military warplanners bent upon destroying specific targets.
However, it is the thermal effects which hold the greatest potential for
environmental damage and human destruction. This is because nuclear
firestorms in urban areas can create millions of tons of smoke which will rise
into the stratosphere and create massive global cooling by blocking
sunlight. In any nuclear conflict, it is likely that this environmental
catastrophe will cause more fatalities than would the initial immediate local
effects of the nuclear detonation.
Figure 2 : Illustration of thermal effects for a 15 kiloton bomb.
Regions 1, 2, 3 refer to the degree of burns sustained during the explosion.
People who sustain third degree burns are unlikely to survive without immediate
medical attention
The surface of the fireball also
emits large amounts of infrared, visible and ultraviolet rays in the first few
seconds. This thermal radiation travels outward at the speed of light. As a
result this is by far the most widespread of all the effects in a nuclear
explosion and occurs even at distances where blast effects are minimal.
The range of thermal effects
increases markedly with weapon yield (thermal radiation decays only as the
inverse square of the distance from the detonation). Large nuclear weapons (in
the megaton class and above) can start fires and do other thermal damage at
distances far beyond the distance at which they can cause blast damage.
Even with a 15 kiloton detonation,
the intensity of the thermal radiation can exceed 1000 Watts per square cm.
This is similar to getting burnt by an acetylene torch used for welding metals.
For a 15 kiloton bomb, almost everyone within 2 km will suffer third degree burns
(which damage the skin and tissues below it); for 550 kiloton bomb, third
degree burns occur in a radius up to 9 km. There will be almost no survivors
since no immediate medical attention will be available (the entire U.S. has
specialized facilities to treat 1500 burn victims).
When studying the effects of a
single weapon, it is important to remember that thousands of U.S. and Russian
nuclear weapons with yields 8 to 50 times larger than 15 kilotons remain on
high-alert, quick-launch status. In a U.S.-Russian nuclear war, these
scenarios would occur thousands of times over in virtually every major city in
the U.S., Russia, and NATO member states (and probably in China).
It is the cumulative effects of
these firestorms – the creation of a stratospheric smoke layer resulting in
deadly global climate change – which ultimately become the primary
environmental consequence of nuclear war which threatens the continued human
existence.
There basically are two kinds of
ionizing radiation created by nuclear explosions, electromagnetic and
particulate. Radiation emitted at the time of detonation is known as prompt or
initial radiation, and it occurs within the first minute of detonation. Anyone
close enough to the detonation to be killed by prompt radiation is likely to be
killed by blast and thermal effects, so most concerns about the health effects
of radiation focus upon the residual or delayed radiation, which is caused by
the decay of radioactive isotopes and is commonly known as radioactive
fallout.
If the fireball of the nuclear
detonation touches the surface of the Earth, large amounts of soil, water, etc.
will be vaporized and drawn up into the radioactive cloud. This material
then also becomes highly radioactive; the smaller particles will rise into the
stratosphere and be distributed globally while the larger particles will settle
to Earth within about 24 hours as local fallout. Lethal levels of fallout can
extend many hundreds of kilometers and miles from the blast area.
Contaminated areas can remain uninhabitable for tens or hundreds of years.
Radiation injury has a long-term
effect on survivors. Reactive chemicals released by ionization cause damage to
DNA and disrupt cells by producing immediate effects on metabolic and
replication processes. While cells can repair a great deal of the genetic
damage, that takes time, and repeated injuries make it that much more
difficult. Immediate treatment requires continual replacement of blood so that
the damaged blood cells are replaced, and treatment of bone marrow and
lymphatic tissues which are amongst the most sensitive to radiation. One must
remember in this context that there are very few hospitals equipped to carry
out such remedial procedures.
Radiation injury is measured in a
unit called rem. Some authorities consider 5 rem/year tolerable for workers who
are occupationally exposed to radiation —a typical value for exposure to
medical X-rays is 0.08 rem. 1.5 rem/year is considered tolerable for pregnant
women. It should be remembered that natural radiation is always present in the
atmosphere over most places on the earth, but at lower levels. However, there
is no threshold, universally agreed upon, at which a dose of radiation can be
declared safe.
Things which get irradiated by
“prompt” radiation themselves become radioactive. People in the area of a
nuclear explosion, and those subject to radioactive fallout stand more risk of
contracting cancer. A 1000 rem exposure for the whole body over a lifetime
(which is entirely possible for those surviving a nuclear war) brings about an
80% chance of contracting cancer.
Cancer from radiation exposure will
occur over the entire lifetime of exposed populations. For example, only
one-half of the predicted numbers of cancer have occurred in the people exposed
to the radiation produced by the atmospheric weapons tests and the explosions
of the US atomic bombs in Hiroshima and Nagasaki that took place 50 to 60 years
ago.
We have no idea what the long-term
genetic consequences will be from the massive release of radioactive fallout on
a world-wide basis.
Ionizing radiation from the fireball
produces intense currents and electromagnetic fields, usually referred to as the
electromagnetic pulse (EMP). This pulse is felt over very large distances. A
single high-yield nuclear detonation will create destructive EMP over hundreds
of thousands of square kilometers beneath where the explosion occurs.
EMP from high-yield nuclear
detonations will subject electrical grids to voltage surges far exceeding those
caused by lightning. Modern VLSI chips and microprocessors, present in most
communication equipment. TVs, radios, computers and other electronic equipment
are extremely sensitive to these surges and immediately get burnt out. Thus all
possible communication links to the outside world are cut off. Restoring these
facilities will be an arduous (and expensive) task assuming that the
infrastructure required to complete this task would still exist following a
nuclear war.
Warplanners consider the EMP from
the detonation of a high-yield warhead as capable of disrupting the entire
communication system of their nation, and in this way a single missile launch
could begin a nuclear war.
Massive absorption of warming
sunlight by a global smoke layer would cause Ice Age temperatures on Earth.
NASA computer models predict 40% of the smoke would stay in the stratosphere
for 10 years. There the smoke would also destroy much of the protective ozone
layer and allow dangerous amounts of UV light to reach the Earth's surface.
Half of 1% of the explosive power of
the deployed nuclear arsenal can create nuclear darkness. 100 Hiroshima-size weapons exploded in the large cities of
India and Pakistan would put 5 million tons of smoke in the stratosphere and
drop average global temperatures to Little Ice Age levels. Shortened growing
seasons could cause up to 1 billion people to starve to death.
A large nuclear war could put 150
million tons of smoke in the stratosphere and make global temperatures colder
than they were 18,000 years ago during the coldest part of the last Ice Age. Killing frosts would occur every day for 1-3 years in the
large agricultural regions of the Northern Hemisphere. Average global
precipitation would be reduced by 45%. Earth’s ozone layer would be decimated.
A large nuclear war would utterly
devastate the environment and cause most people to starve to death. Already stressed ecosystems would collapse. Deadly climate
change, radioactive fallout and toxic pollution would cause a mass extinction
event, eliminating humans and most complex forms of life on Earth.
The U.S. and Russia keep hundreds of
missiles armed with thousands of nuclear warheads on high-alert, 24 hours a
day.
They can be launched with only a few
minutes warning and reach their targets in less than 30 minutes. We must end
this madness.
Wednesday, 7 August 2013 0
Sunday, 31 March 2013
One of the nicest things about our new place is its proximity to Puttachi's school. Though I drive her to school (as of now), I bring her back walking. The lovely thing about coming back walking with her is that I hear all her school news, hot off the press. We are lucky to have a quiet, tree-lined road part of the way, and as we walk, Puttachi swings her bag, and skips along, ponytails bouncing, and she chatters away. Contrast this with driving back - my eyes are on the road, she is in the back seat, and I am only half-listening to what she says.. and since she also doesn't get the eye-contact and reactions she needs, she becomes quiet too (relatively.)
It is just a kilometre's walk, but it surprises me that everybody who hears that I bring her back walking says, "Isn't she tired after school?" and "Can she walk that distance?" She is as tired as an active kid is after school, but this leisurely, short walk doesn't make her more tired. Of course, there are days when she doesn't feel too good, or she has fallen down at school and complains of aches, but I always carry enough money for an autorickshaw in case she cannot walk at all. But more often than not, once she starts talking (and walking), she makes it home pretty easily. The second question - seriously? 1 km? It is nothing. The very people who are surprised that she walks that distance would have walked many times that distance when they were Puttachi's age. I think the adults of today underestimate our children. We presume weakness in them.
Walking is such a dying art - very few people walk to a friend's house, to a shop, or to the barber. Distances, traffic and smoke, creepily lonely roads and uneven footpaths are all culprits. As a result, even when the conditions are conducive to walking, people don't even remember that they can include walking among their options.
Walking is such joy - the freedom to go where you want to, the luxury not to have to park your vehicle anywhere, the feeling of being part of the landscape, the space you get to think when you are alone, or the opportunity to have good conversations when you are with company..... I come from a family of great walkers, and I am married to an extreme walker, if there is any such phrase, and I think Puttachi has already been inculcated in this "art" - I hope that the future gives her the space and the opportunity to continue to experience the pleasure of walking.
It is just a kilometre's walk, but it surprises me that everybody who hears that I bring her back walking says, "Isn't she tired after school?" and "Can she walk that distance?" She is as tired as an active kid is after school, but this leisurely, short walk doesn't make her more tired. Of course, there are days when she doesn't feel too good, or she has fallen down at school and complains of aches, but I always carry enough money for an autorickshaw in case she cannot walk at all. But more often than not, once she starts talking (and walking), she makes it home pretty easily. The second question - seriously? 1 km? It is nothing. The very people who are surprised that she walks that distance would have walked many times that distance when they were Puttachi's age. I think the adults of today underestimate our children. We presume weakness in them.
Walking is such a dying art - very few people walk to a friend's house, to a shop, or to the barber. Distances, traffic and smoke, creepily lonely roads and uneven footpaths are all culprits. As a result, even when the conditions are conducive to walking, people don't even remember that they can include walking among their options.
Walking is such joy - the freedom to go where you want to, the luxury not to have to park your vehicle anywhere, the feeling of being part of the landscape, the space you get to think when you are alone, or the opportunity to have good conversations when you are with company..... I come from a family of great walkers, and I am married to an extreme walker, if there is any such phrase, and I think Puttachi has already been inculcated in this "art" - I hope that the future gives her the space and the opportunity to continue to experience the pleasure of walking.
Sunday, 31 March 2013 0
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