11.2 Effects of Radiation Exposure in the Vicinity of the Detonation
103
exposure is about 1400 m, at which distance the gamma radiation dose will be about
4 Sv and the neutron dose will be between 0.4 and 0.8 Sv. The cumulative dose,
4.4–4.8 Sv has a survival rate of about 50% in the absence of medical care and about
75% with expert medical attention [6]. This does not mean that the majority, or even
half, of those at this distance will survive as radiation is only one of the hazards they
face (the others being the blast, thermal effects, collapsing buildings, etc. mentioned
earlier). Considering the large number of people (tens or hundreds of thousands,
depending on the city attacked) many of these people are likely to be badly injured
and unable to receive the medical care they will need in order to survive, thus the
majority of these people are likely to die of their injuries and radiation exposure.
It should also be noted that the gamma radiation exposures mentioned above are
for people who can see the location of the bomb—who are in the line of sight. The
presence of terrain and of buildings, particularly large masonry structures, can reduce
this exposure considerably, in some cases to survivable levels even for those only a
few hundred meters from the bomb. However, the neutron exposure at these close
distances might well remain dangerous because metal, glass, and masonry are not
effective at attenuating neutron radiation.
11.3 Effects of Radiation Exposure in the Fallout Plume
The majority of those who are close enough to receive a fatal dose of radiation from
the detonation of the weapon itself will not live long enough to die of radiation
exposure; they will be killed by blast injuries, collapsing buildings, or the mass
fires. And while the thought of 100,000–200,000 deaths in this zone is horrendous
to contemplate, the potential death toll among those exposed to the fallout plume
might be higher still. More importantly, while there is little that can be done to reduce
the number of deaths from the explosion itself, taking proper actions can virtually
eliminate all deaths among those exposed only to fallout.
A surface burst will vaporize many of the materials within the fireball and the
heat of the explosion coupled with the fires will loft these materials high into the
atmosphere where they will begin to cool and condense. This process will take some
time to occur and the fallout will not begin to reach the surface again for a period
of time following the detonation—the amount of time will depend on the amount of
thermal energy and how high that takes material from the ground, the sizes of the
particles that form, and the speed with which they drift back to the ground. During
this time, the winds at both the surface and aloft will be carrying these particles
downwind in whichever direction that happens to be at various altitudes; this will
tend to scatter the fallout laterally (broadening the plume) as well as along the axis
of its travel (lengthening the plume). These factors are to some extent random, which
is why a Gaussian approximation will provide a reasonable first approximation of
the distribution of radioactivity deposition across the plume. Along the plume’s axis,
however, the process is more systematic in that the largest and heaviest particles will
tend to settle first, closest to the site of the detonation and the lightest particles will
103
exposure is about 1400 m, at which distance the gamma radiation dose will be about
4 Sv and the neutron dose will be between 0.4 and 0.8 Sv. The cumulative dose,
4.4–4.8 Sv has a survival rate of about 50% in the absence of medical care and about
75% with expert medical attention [6]. This does not mean that the majority, or even
half, of those at this distance will survive as radiation is only one of the hazards they
face (the others being the blast, thermal effects, collapsing buildings, etc. mentioned
earlier). Considering the large number of people (tens or hundreds of thousands,
depending on the city attacked) many of these people are likely to be badly injured
and unable to receive the medical care they will need in order to survive, thus the
majority of these people are likely to die of their injuries and radiation exposure.
It should also be noted that the gamma radiation exposures mentioned above are
for people who can see the location of the bomb—who are in the line of sight. The
presence of terrain and of buildings, particularly large masonry structures, can reduce
this exposure considerably, in some cases to survivable levels even for those only a
few hundred meters from the bomb. However, the neutron exposure at these close
distances might well remain dangerous because metal, glass, and masonry are not
effective at attenuating neutron radiation.
11.3 Effects of Radiation Exposure in the Fallout Plume
The majority of those who are close enough to receive a fatal dose of radiation from
the detonation of the weapon itself will not live long enough to die of radiation
exposure; they will be killed by blast injuries, collapsing buildings, or the mass
fires. And while the thought of 100,000–200,000 deaths in this zone is horrendous
to contemplate, the potential death toll among those exposed to the fallout plume
might be higher still. More importantly, while there is little that can be done to reduce
the number of deaths from the explosion itself, taking proper actions can virtually
eliminate all deaths among those exposed only to fallout.
A surface burst will vaporize many of the materials within the fireball and the
heat of the explosion coupled with the fires will loft these materials high into the
atmosphere where they will begin to cool and condense. This process will take some
time to occur and the fallout will not begin to reach the surface again for a period
of time following the detonation—the amount of time will depend on the amount of
thermal energy and how high that takes material from the ground, the sizes of the
particles that form, and the speed with which they drift back to the ground. During
this time, the winds at both the surface and aloft will be carrying these particles
downwind in whichever direction that happens to be at various altitudes; this will
tend to scatter the fallout laterally (broadening the plume) as well as along the axis
of its travel (lengthening the plume). These factors are to some extent random, which
is why a Gaussian approximation will provide a reasonable first approximation of
the distribution of radioactivity deposition across the plume. Along the plume’s axis,
however, the process is more systematic in that the largest and heaviest particles will
tend to settle first, closest to the site of the detonation and the lightest particles will