66
7 Physical Effects of Radiological Weapons
Fires pose risks beyond the obvious concerns about burns, smoke inhalation,
destruction of property, and so forth. Fires can also create winds that can resuspend
radioactive particles, the rising thermal columns of air from fires can inject these
particles into the atmosphere, and winds can spread this contamination far downwind.
Some studies (e.g. [9]) concluded that appreciable amounts of contamination can be
spread a few tens of kilometers downwind if the contamination is lofted high enough
into the atmosphere to be caught by upper-level winds; this can be accomplished by
the blast itself or by fires started by a suitable explosion.
The water used to combat fires can also help to spread contamination; radioactivity can be washed down streets and into the storm sewers by the water used for
firefighting, contaminating the sewers and (depending on the sewer system design)
possibly also contaminating waste water treatment plants. Fortunately, studies have
shown that properly working water treatment plants are very effective at removing
radioactivity from waste water, but the plants themselves will become contaminated.
Care must also be taken to segregate the solids produced by waste water treatment
to prevent contamination of the landfills or fields to which these solids are removed
for disposal [10].
7.5 Flying Objects
The blast from a bomb is capable of throwing objects long distances at high speeds;
these objects can be pieces from the bomb itself and whatever it is that contains the
bomb (e.g. suitcase, car, trash can, etc.), nearby objects that are picked up or blown
off of nearby objects by the blast (e.g. street signs, soda cans, pieces of asphalt and
brick, etc.), and any other items that can be mobilized by the blast wave. There have
even been examples of teeth and fragments of bone from a suicide bomber becoming
shrapnel [11]. The distance these objects can be thrown depends on the strength of the
explosion, the weight of the object, and their aerodynamic properties; a small piece
of dense metal will be propelled further than, say, a street sign of the same weight but
with a larger cross-sectional area. For this reason, a number of organizations have
developed recommendations for safe stand-off distances from a variety of bomb
sizes. These distances range from about 20 m (the mandatory evacuation distance
from a 2-kg pipe bomb) to about 3 km (the preferred evacuation distance from a
30-ton truck bomb [17, 18] (Fig. 7.2).
Among the materials that can be scattered by an RDD are fragments of the source
itself as well as radioactive powders or liquids (depending on the physical form of
the source(s) used. Thus, in the aftermath of an attack using an explosive RDD,
personnel approaching the scene should enter from the upwind direction or laterally
if possible and should monitor for elevated radiation dose rates when they are at least
as far away as the distances noted on this table. The force of the explosion can also
inject these powders or liquids into the air where they can be spread downwind; this
will be discussed in greater detail in the following section.
7 Physical Effects of Radiological Weapons
Fires pose risks beyond the obvious concerns about burns, smoke inhalation,
destruction of property, and so forth. Fires can also create winds that can resuspend
radioactive particles, the rising thermal columns of air from fires can inject these
particles into the atmosphere, and winds can spread this contamination far downwind.
Some studies (e.g. [9]) concluded that appreciable amounts of contamination can be
spread a few tens of kilometers downwind if the contamination is lofted high enough
into the atmosphere to be caught by upper-level winds; this can be accomplished by
the blast itself or by fires started by a suitable explosion.
The water used to combat fires can also help to spread contamination; radioactivity can be washed down streets and into the storm sewers by the water used for
firefighting, contaminating the sewers and (depending on the sewer system design)
possibly also contaminating waste water treatment plants. Fortunately, studies have
shown that properly working water treatment plants are very effective at removing
radioactivity from waste water, but the plants themselves will become contaminated.
Care must also be taken to segregate the solids produced by waste water treatment
to prevent contamination of the landfills or fields to which these solids are removed
for disposal [10].
7.5 Flying Objects
The blast from a bomb is capable of throwing objects long distances at high speeds;
these objects can be pieces from the bomb itself and whatever it is that contains the
bomb (e.g. suitcase, car, trash can, etc.), nearby objects that are picked up or blown
off of nearby objects by the blast (e.g. street signs, soda cans, pieces of asphalt and
brick, etc.), and any other items that can be mobilized by the blast wave. There have
even been examples of teeth and fragments of bone from a suicide bomber becoming
shrapnel [11]. The distance these objects can be thrown depends on the strength of the
explosion, the weight of the object, and their aerodynamic properties; a small piece
of dense metal will be propelled further than, say, a street sign of the same weight but
with a larger cross-sectional area. For this reason, a number of organizations have
developed recommendations for safe stand-off distances from a variety of bomb
sizes. These distances range from about 20 m (the mandatory evacuation distance
from a 2-kg pipe bomb) to about 3 km (the preferred evacuation distance from a
30-ton truck bomb [17, 18] (Fig. 7.2).
Among the materials that can be scattered by an RDD are fragments of the source
itself as well as radioactive powders or liquids (depending on the physical form of
the source(s) used. Thus, in the aftermath of an attack using an explosive RDD,
personnel approaching the scene should enter from the upwind direction or laterally
if possible and should monitor for elevated radiation dose rates when they are at least
as far away as the distances noted on this table. The force of the explosion can also
inject these powders or liquids into the air where they can be spread downwind; this
will be discussed in greater detail in the following section.