5.2 Types of Radiological Weapons
45
noted that covertly dispersing radioactive materials might have a greater impact on
public health, especially if the radionuclide(s) used were the more-damaging and lessdetectible alpha emitters such as the Po-210 used to assassinate former KGB agent
Alexander Litvenenko in November, 2006 [24]. Zimmerman noted that, because it is
so weakly penetrating, alpha radiation was not normally considered to be effective as
an RDD isotope. But as the Litvenenko case demonstrated, relatively small amounts
of alpha-emitting radionuclides, if ingested or inhaled, could be dangerous.
The most serious problem associated with a covert radiological attack is that
nobody might know when the attack actually took place [10]. Consider a terrorist,
for example, who surreptitiously spreads radioactivity in a heavily trafficked location such as a train station. Unless the station is monitored for radiation and/or
radioactivity this will not be detected immediately, and possibly not for some time
afterwards. In fact, the first detection might occur in a different location such as a
university or nuclear power plant where surveys are performed on a regular basis.
Now consider press reports that radioactivity was discovered in multiple locations
around the city, spread by people passing through the train station, and the impact
of this report on the city in question. As time goes on, more and more contaminated
locations are identified and the citizens can only wonder how far it has spread, if
they have been contaminated, and what the impact will be on their health and that of
their friends and family.
This is the problem with a covert radiological attack—since nobody might know
exactly when and where it occurred, the entire population of the city might consider
themselves to be at risk, as well as commuters, tourists, and other visitors. This can
obviously be disruptive to the city, businesses, and the people of the city.
However, launching a covert radiological attack is not necessarily a simple matter;
especially in any of the many cities that are protected by robust interdiction networks,
and even more so if the intent is to cause physical harm to those in the city. This is
because gamma-emitting radionuclides must be shielded to prevent detection, and
even alpha- and beta-emitting radionuclides frequently emit ancillary gamma or xrays that can be detected at a distance (Am-241, for example, emits a gamma ray with
an energy of about 60 keV, Ra-226 emits a 186 keV gamma, and so forth). In addition,
beta-emitters produce x-ray radiation through the process of bremsstrahlung when
the beta particles pass through shielding materials. This photon radiation can be
detected, even if the particulate radiation is easily shielded.
As with an overt release, the covert dispersal of radioactivity is unlikely to pose
a large threat to the health and safety of people living in the affected city. But even
so, such an attack can have a significant financial and economic impact and can
prove to be tremendously disruptive to the city and its citizens. Something else to
keep in mind is that a covert radiological attack combines two significant fears—
an instinctive fear of the unknown with the learned fear of radiation. Humans are
instinctively frightened of what they do not know—the unknown can carry danger—
and they learn to be frightened of radiation, partly because so few people have any
real understanding of radiation and what it can do (i.e. fear of the unknown) and
partly because what they do hear in the media is so often alarming or frightening.
45
noted that covertly dispersing radioactive materials might have a greater impact on
public health, especially if the radionuclide(s) used were the more-damaging and lessdetectible alpha emitters such as the Po-210 used to assassinate former KGB agent
Alexander Litvenenko in November, 2006 [24]. Zimmerman noted that, because it is
so weakly penetrating, alpha radiation was not normally considered to be effective as
an RDD isotope. But as the Litvenenko case demonstrated, relatively small amounts
of alpha-emitting radionuclides, if ingested or inhaled, could be dangerous.
The most serious problem associated with a covert radiological attack is that
nobody might know when the attack actually took place [10]. Consider a terrorist,
for example, who surreptitiously spreads radioactivity in a heavily trafficked location such as a train station. Unless the station is monitored for radiation and/or
radioactivity this will not be detected immediately, and possibly not for some time
afterwards. In fact, the first detection might occur in a different location such as a
university or nuclear power plant where surveys are performed on a regular basis.
Now consider press reports that radioactivity was discovered in multiple locations
around the city, spread by people passing through the train station, and the impact
of this report on the city in question. As time goes on, more and more contaminated
locations are identified and the citizens can only wonder how far it has spread, if
they have been contaminated, and what the impact will be on their health and that of
their friends and family.
This is the problem with a covert radiological attack—since nobody might know
exactly when and where it occurred, the entire population of the city might consider
themselves to be at risk, as well as commuters, tourists, and other visitors. This can
obviously be disruptive to the city, businesses, and the people of the city.
However, launching a covert radiological attack is not necessarily a simple matter;
especially in any of the many cities that are protected by robust interdiction networks,
and even more so if the intent is to cause physical harm to those in the city. This is
because gamma-emitting radionuclides must be shielded to prevent detection, and
even alpha- and beta-emitting radionuclides frequently emit ancillary gamma or xrays that can be detected at a distance (Am-241, for example, emits a gamma ray with
an energy of about 60 keV, Ra-226 emits a 186 keV gamma, and so forth). In addition,
beta-emitters produce x-ray radiation through the process of bremsstrahlung when
the beta particles pass through shielding materials. This photon radiation can be
detected, even if the particulate radiation is easily shielded.
As with an overt release, the covert dispersal of radioactivity is unlikely to pose
a large threat to the health and safety of people living in the affected city. But even
so, such an attack can have a significant financial and economic impact and can
prove to be tremendously disruptive to the city and its citizens. Something else to
keep in mind is that a covert radiological attack combines two significant fears—
an instinctive fear of the unknown with the learned fear of radiation. Humans are
instinctively frightened of what they do not know—the unknown can carry danger—
and they learn to be frightened of radiation, partly because so few people have any
real understanding of radiation and what it can do (i.e. fear of the unknown) and
partly because what they do hear in the media is so often alarming or frightening.