Chapter 10
Physical Effects of Nuclear Weapons
In the previous chapter we saw a description of the first seconds of a nuclear explosion;
we will now see what happens in the minutes and hours that follow. In particular,
we will look at the impact of the blast, thermal, and the radiological aftermath of the
attack. At any given location these effects will vary according to the strength of the
device and the distance from the point of detonation.
Yet another factor affecting nuclear weapons effects is the altitude of the explosion.
Overpressure from surface burst (when a nuclear weapon is detonated at or very near
ground level) is about 60% that of an airburst detonated at 1700 feet above ground,
while the thermal effects of a surface burst are about 75% as severe as those from
a burst at this altitude [1]. This is why the Hiroshima and Nagasaki devices were
detonated as airbursts—to maximize the destruction caused by blast and thermal
effects.
Very significantly, the altitude of a detonation has a dramatic effect on the amount
of fallout produced by a nuclear explosion. Most materials that are within the volume
of the fireball will be vaporized. As the fireball expands and cools, these materials
will begin to condense and, as they do so, the radioactive fission products become
incorporated into the condensing particles and they fall back to earth as fallout. As
the detonation altitude increases, the amount of material incorporated into the fireball
drops, and the amount of fallout decreases; the fission products fall to Earth over a
larger area and form a more diffuse fallout plume.
We must remember that, although there will be massive loss of life and destruction
up to a distance of a few miles from a surface burst in the range of a few tens of kt
(the size of the Hiroshima and Nagasaki weapons), most of our major cities are far
larger than this. This means that we can expect that most of a major city will survive
a nuclear attack. We must also remember that large amounts of radioactive fallout
will be generated, and this will spread far beyond the range of destruction; once
we progress beyond the radius of destruction we should expect to see wide-spread
radioactive contamination, possibly to great distances from the site of the attack.
© Springer Nature Switzerland AG 2021
P. A. Karam, Radiological and Nuclear Terrorism,
Advanced Sciences and Technologies for Security Applications,
https://doi.org/10.1007/978-3-030-69162-2_10
91
Physical Effects of Nuclear Weapons
In the previous chapter we saw a description of the first seconds of a nuclear explosion;
we will now see what happens in the minutes and hours that follow. In particular,
we will look at the impact of the blast, thermal, and the radiological aftermath of the
attack. At any given location these effects will vary according to the strength of the
device and the distance from the point of detonation.
Yet another factor affecting nuclear weapons effects is the altitude of the explosion.
Overpressure from surface burst (when a nuclear weapon is detonated at or very near
ground level) is about 60% that of an airburst detonated at 1700 feet above ground,
while the thermal effects of a surface burst are about 75% as severe as those from
a burst at this altitude [1]. This is why the Hiroshima and Nagasaki devices were
detonated as airbursts—to maximize the destruction caused by blast and thermal
effects.
Very significantly, the altitude of a detonation has a dramatic effect on the amount
of fallout produced by a nuclear explosion. Most materials that are within the volume
of the fireball will be vaporized. As the fireball expands and cools, these materials
will begin to condense and, as they do so, the radioactive fission products become
incorporated into the condensing particles and they fall back to earth as fallout. As
the detonation altitude increases, the amount of material incorporated into the fireball
drops, and the amount of fallout decreases; the fission products fall to Earth over a
larger area and form a more diffuse fallout plume.
We must remember that, although there will be massive loss of life and destruction
up to a distance of a few miles from a surface burst in the range of a few tens of kt
(the size of the Hiroshima and Nagasaki weapons), most of our major cities are far
larger than this. This means that we can expect that most of a major city will survive
a nuclear attack. We must also remember that large amounts of radioactive fallout
will be generated, and this will spread far beyond the range of destruction; once
we progress beyond the radius of destruction we should expect to see wide-spread
radioactive contamination, possibly to great distances from the site of the attack.
© Springer Nature Switzerland AG 2021
P. A. Karam, Radiological and Nuclear Terrorism,
Advanced Sciences and Technologies for Security Applications,
https://doi.org/10.1007/978-3-030-69162-2_10
91