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13 Developing a Radiological and Nuclear Interdiction Network
13.7 Conducting Interdiction Surveys
Among the first things a radiation worker is taught is how to perform an effective
radiation survey. They are taught this because we cannot sense radiation or radioactive contamination, their instruments are their “eyes” and if they do not use their
instruments properly they will be blind to even high levels of radiation or contamination. They are taught, too, the importance of performing disciplined surveys, paying
close attention to the speed of the detector, its distance from the area (or object)
being surveyed, and they are trained to pay close attention to covering as much of
the area being surveyed as possible. While there are times requiring a quick survey,
these occasions are rare and, even then, the initial scoping survey is almost invariably
followed by a more careful and thorough survey (e.g. [9].)
Police work is quite different. While police will perform painstakingly thorough
investigations of a crime scene, this only constitutes a small part of routine police
work. A police officer searching for a missing child, for example, needs to quickly
assess an area to see if the child (or a suspicious-looking adult) is there and, if not,
to quickly move on to the next location. Pilots who are searching for a missing elder
realize that a person on foot does not move very quickly so they tend to circle the area
where the person was last seen, using their eyes and their cameras to comb the area
for the face (or the clothing) they’ve been told to search for. If they are searching for
an escaping criminal, whether from the ground or from the air, they might well be
looking for the disturbance caused by a person running through a crowded sidewalk
or darting across traffic.
These search techniques are well-suited for normal police missions, but they are
not ideal for finding radioactive sources. The author has participated in a large number
of radiological interdiction surveys on foot, in vehicles, on boats, and in helicopters.
In each setting he has noticed some practices that, while understandable in the context
of normal police work, detract from the survey’s effectiveness.
Another point that needs to be made is that a survey that fails to turn up a source
does not mean that there is no source to be found, it only means that there were no
sources that could be found with the instruments being used. For example, a search
with gamma detectors will not detect alpha- or beta-emitting sources. Not only that,
but even a gamma-emitting radionuclide might not be detected if it is a low-activity
source, if the source emits low-energy gammas, or if the source is well-shielded.
This does not mean that conducting interdiction surveys is worthless or a waste of
time, it simply means that those managing interdiction efforts need to understand the
limitations of the surveys being performed and should remember that they are only
one part of the overall interdiction effort.
13 Developing a Radiological and Nuclear Interdiction Network
13.7 Conducting Interdiction Surveys
Among the first things a radiation worker is taught is how to perform an effective
radiation survey. They are taught this because we cannot sense radiation or radioactive contamination, their instruments are their “eyes” and if they do not use their
instruments properly they will be blind to even high levels of radiation or contamination. They are taught, too, the importance of performing disciplined surveys, paying
close attention to the speed of the detector, its distance from the area (or object)
being surveyed, and they are trained to pay close attention to covering as much of
the area being surveyed as possible. While there are times requiring a quick survey,
these occasions are rare and, even then, the initial scoping survey is almost invariably
followed by a more careful and thorough survey (e.g. [9].)
Police work is quite different. While police will perform painstakingly thorough
investigations of a crime scene, this only constitutes a small part of routine police
work. A police officer searching for a missing child, for example, needs to quickly
assess an area to see if the child (or a suspicious-looking adult) is there and, if not,
to quickly move on to the next location. Pilots who are searching for a missing elder
realize that a person on foot does not move very quickly so they tend to circle the area
where the person was last seen, using their eyes and their cameras to comb the area
for the face (or the clothing) they’ve been told to search for. If they are searching for
an escaping criminal, whether from the ground or from the air, they might well be
looking for the disturbance caused by a person running through a crowded sidewalk
or darting across traffic.
These search techniques are well-suited for normal police missions, but they are
not ideal for finding radioactive sources. The author has participated in a large number
of radiological interdiction surveys on foot, in vehicles, on boats, and in helicopters.
In each setting he has noticed some practices that, while understandable in the context
of normal police work, detract from the survey’s effectiveness.
Another point that needs to be made is that a survey that fails to turn up a source
does not mean that there is no source to be found, it only means that there were no
sources that could be found with the instruments being used. For example, a search
with gamma detectors will not detect alpha- or beta-emitting sources. Not only that,
but even a gamma-emitting radionuclide might not be detected if it is a low-activity
source, if the source emits low-energy gammas, or if the source is well-shielded.
This does not mean that conducting interdiction surveys is worthless or a waste of
time, it simply means that those managing interdiction efforts need to understand the
limitations of the surveys being performed and should remember that they are only
one part of the overall interdiction effort.