When a nuclear weapon is detonated massive
amounts of energy are released in a fraction of a second. The energy
is made up of x-rays (radiation) , neutrons and fission products
(high energy particles). Moments after the detonation a fire ball
complete with a blast wave travelling faster the sound will envelope
The blast can be split into
four separate stages.
nuclear blast the heat arrives first. This is known as the thermal
pulse. The heat can directly ignite buildings and debris. This can
lead to fire storms. A fireball from a 1 mega ton weapon would be
440ft in diameter 1 millisecond after explosion.
Within 10 seconds it would be 7000ft. After 20 seconds it would be
travelling at 330 mph and have a diameter of almost 1 mile across.
35% of energy in a nuclear
blast is thermal radiation. The heat at ground zero is 1,000,000
oC. The same as the interior of the Sun.
The amount of heat energy received a certain
distance from the nuclear explosion depends on the power of the
weapon and the state of the atmosphere. If the visibility
is poor or the explosion takes place above clouds, the
effectiveness of the heat flash is decreased. The thermal radiation
falling on exposed skin will cause flash burns.
A 1Mt blast causes 1st degree burns at 7 miles (similar to
At six miles, blisters and permanent scaring and at five
miles 3rd degree burns which destroy skin. The blast can cause flash
blindness at 13 miles and up to 50 miles if it occurs at night. Most
ordinary clothing provides protection from the heat radiation, as
does almost any opaque object.
Flash burns occur when the bare skin is directly exposed, or if the
clothing is too thin to absorb the thermal radiation.
Under some conditions, such as existed at
Hiroshima but not at Nagasaki, many individual fires can combine to
produce a firestorm similar to those that accompany some large
forest fires. The heat of the fire causes a strong up draught, which
produces strong winds drawn in towards the centre of the burning
area. These winds fan the flames and convert the area into a
holocaust in which everything flammable is destroyed. Inasmuch as
the flames are drawn inward, however, the area over which such a
fire spreads may be limited.
After the thermal pulse comes
enormous amounts of pressure created by the blast itself. As is the
case with explosions caused by conventional weapons, most of the
damage to buildings and other structures results directly, or
indirectly , from the effects of the blast.
Damage is caused by over
pressure at the front of the blast wave and the extremely strong
wind which follow
soon after the wave passed.
Dust and radioactive particles
are sucked up from the immediate vicinity of the explosion into the
large rising fireball. At this stage the radiation is fairly
contained. All those who would have been affected by it have already
been killed or seriously injured by the thermal pulse and blast
The energy from the explosion
creates penetrating radiation.
When absorbed by the body nuclear radiation causes serious injury.
A nuclear explosion creates 2
types of radiation.
The two types of radiation produced by a nuclear explosion are:
This is visible , similar to
light. The rays are hard to shield against. They are a factor in
contamination of living organisms.
This occurs when neutron
radiation reacts with animal tissue. The electric field produced by
the positively charged ion or negatively charged electron can damage
DNA. This could cause the cells to die, become incapable of
reproducing or mutate.
Both gamma rays and neutron
radiation are capable of penetrating solid matter, so substantial
thicknesses of material are required if they are to provide adequate
shielding from the hazard.
Radioactive fallout travels up
into the stratosphere. The heavier particles fall locally and
contaminate the surrounding land and water. Smaller particles enter
the wind stream and can be carried many thousands of miles before
falling back to earth. If these particles are ingested by living
organisms serious illness or death often results.
Carbon—circulation path still
unclear, this biological effects unclear.
Strontium 90—similar to
calcium so effects bones causes tumours or leukaemia.
Caesium— no major problems.
Plutonium— has a half life of
24hrs. Ingesting 1 microgram (a tiny amount) has serious health
Iodine 131—concentrates in milk
produces and thyroid glands.
Other radiation fallout symptoms include blood disorder , cataracts
, malignant tumours (esp. in breast , lung and thyroid)
Although not a health danger to
humans the EMP is a powerful surge in electrical magnetic energy.
This is capable of overloading
power supplies and burning out both capacitors and transistors.
A single 10mt bomb would be
capable of knocking out telecommunications and all electronic
equipment on a nationwide scale. In 1962 a 1.4mt bomb was detonated
400km above the earth. The EMP destroyed street lights 1200km away
As we can see, the effects of a
nuclear blast are many and massive. However, nuclear weapons have
one more major cause for concern.
The radiation they release
will be hazardous for many years after the initial explosion,
effectively turning the land and water around the epicentre of the
blast unusable for many years, possibly decades.