13.4 Instrument Selection
137
of a nuclear attack) neutron radiation, at dose rates ranging from near-background
to several Gy or Sv hr
−1 . This can be accomplished with a combination of pressurized and air ionization chambers, with a series of energy-compensated GM
detectors, or with any of a number of radiation dosimeters (e.g. direct ion storage
or TLD); neutron dose can be measured using suitable neutron detectors or neutron
dosimeters. Detectors to be used for dose reconstruction are best placed as close as
possible to the location of those whose dose is to be determined; in most cities this
would be at or near ground level, but cities in which a large number of people live
and/or work in skyscrapers should consider placing some detectors or dosimeters
in high-rise buildings as well, perhaps 100-200 meters above ground level.
13.5 Budgetary Considerations
The financial impact of a radiological attack is roughly proportional to the amount
of radioactivity used [1, 2]; the size of the contaminated area, the radiation dose rate
and subsequent health risk, the length of time required for the radioactivity to decay
to acceptable levels…all of these are proportional to the source activity. Thus, the
cost of an attack will—very roughly—be proportional to the amount of radioactivity
present, with high-activity sources being generally more costly than low-activity
sources of the same nuclide.
Zimmerman and Loeb [12] estimated the cost of a radiological attack against
a major city to be on the order of tens of billions of dollars for source containing
several TBq of radioactivity. If we assume that the total cost of an attack is roughly
proportional to the amount of radioactivity used then this implies that an attack using
several GBq would inflict a cost in the tens of millions of dollars and an attack using
several MBq would cost tens of thousands of dollars to recover from. While the
psychological cost of an attack cannot be easily quantified, it seems reasonable to
feel that it might not make sense to spend, say, hundreds of millions of dollars to
establish an interdiction network capable of detecting sources that would lead to only
tens of thousands of dollars in damage and other costs.
The distance at which a given detector can “see” a radioactive source is proportional to the square root of the source activity. Thus, if an interdiction network
requires, say, 100 detectors to stop the movement of a 10 GBq source, it will require
10,000 detectors to stop the movement of a 1 GBq source. In other words, attacks that
cause the least damage will be the most expensive to stop. Each city must determine
how much it can afford to spend and what level of attack (or malicious misuse) it is
willing to accept.
In addition to the initial cost of purchasing radiation detection equipment the
department and city must also consider the costs of training the Tier 2 and Tier 3 users
(both initial and periodic refresher training), instrument maintenance and calibration,
and the replacement of instruments that break or become obsolete. As this book
is being written the National Council on Radiation Protection and Measurements
(NCRP) is developing guidance on calibration and other instrument maintenance that
137
of a nuclear attack) neutron radiation, at dose rates ranging from near-background
to several Gy or Sv hr
−1 . This can be accomplished with a combination of pressurized and air ionization chambers, with a series of energy-compensated GM
detectors, or with any of a number of radiation dosimeters (e.g. direct ion storage
or TLD); neutron dose can be measured using suitable neutron detectors or neutron
dosimeters. Detectors to be used for dose reconstruction are best placed as close as
possible to the location of those whose dose is to be determined; in most cities this
would be at or near ground level, but cities in which a large number of people live
and/or work in skyscrapers should consider placing some detectors or dosimeters
in high-rise buildings as well, perhaps 100-200 meters above ground level.
13.5 Budgetary Considerations
The financial impact of a radiological attack is roughly proportional to the amount
of radioactivity used [1, 2]; the size of the contaminated area, the radiation dose rate
and subsequent health risk, the length of time required for the radioactivity to decay
to acceptable levels…all of these are proportional to the source activity. Thus, the
cost of an attack will—very roughly—be proportional to the amount of radioactivity
present, with high-activity sources being generally more costly than low-activity
sources of the same nuclide.
Zimmerman and Loeb [12] estimated the cost of a radiological attack against
a major city to be on the order of tens of billions of dollars for source containing
several TBq of radioactivity. If we assume that the total cost of an attack is roughly
proportional to the amount of radioactivity used then this implies that an attack using
several GBq would inflict a cost in the tens of millions of dollars and an attack using
several MBq would cost tens of thousands of dollars to recover from. While the
psychological cost of an attack cannot be easily quantified, it seems reasonable to
feel that it might not make sense to spend, say, hundreds of millions of dollars to
establish an interdiction network capable of detecting sources that would lead to only
tens of thousands of dollars in damage and other costs.
The distance at which a given detector can “see” a radioactive source is proportional to the square root of the source activity. Thus, if an interdiction network
requires, say, 100 detectors to stop the movement of a 10 GBq source, it will require
10,000 detectors to stop the movement of a 1 GBq source. In other words, attacks that
cause the least damage will be the most expensive to stop. Each city must determine
how much it can afford to spend and what level of attack (or malicious misuse) it is
willing to accept.
In addition to the initial cost of purchasing radiation detection equipment the
department and city must also consider the costs of training the Tier 2 and Tier 3 users
(both initial and periodic refresher training), instrument maintenance and calibration,
and the replacement of instruments that break or become obsolete. As this book
is being written the National Council on Radiation Protection and Measurements
(NCRP) is developing guidance on calibration and other instrument maintenance that