Dirty Bombs
Forward
This paper has been developed from unclassified sources. It is meant to educate people in the hope that they will not panic in the event a dirty bomb is
detonated, whether it is in their immediate vicinity or somewhere else. The sources of this information are a PBS presentation on the subject of "dirty
bombs," several issues of Time Magazine, and the author's experiences aboard a nuclear submarine and working at a manufacturing company that
built a radiological sanitation facility. The opinions herein and any errors and omissions are those of the author.
What is a "dirty bomb?"
A "dirty bomb," technically called a "Radiologial Dispersal Device," consists of conventional explosives mixed with radioactive material that is dispersed into
the air when detonation occurs. There is no nuclear explosion.
A dirty bomb presents two dangers to living organisms. One danger is short term and the other is long term. The force of the explosion in close proximity to
the detonation is the short-term danger. This danger is usually confined to an area a few yards from the explosion, depending on the amount and type of explosive
used.
The long-term danger is contamination by the radioactive material that is ejected. Depending on the particulate size and the amount of electrical charge on the
material, eventually, it settles.
These are a few Peaceful uses for Radioactive Material:
Medicine
Cesium chloride is commonly used in hospitals to treat tumors using radiation. The Cesium chloride radioactive powder is in hollow metal tubes called "needles."
This substance gives off gamma radiation.
Unauthorized acquisition of this radioactive material is possible.
Crop grains
Cesium chloride has also been used to irradiate grain to prevent it from germinating, lengthening its storage life.
Unauthorized acquisition of this radioactive material is possible.
Remote power units
Strontium 90, a beta ray emitter, was used to power remote navigation systems and lighting units in the former Soviet Union. The radioactive material maintains
a temperature of 800 degrees Fahrenheit. This heat was used to generate electricity. Hundreds of these remote devices are in place, but no longer used, maintained,
or inventoried.
Unauthorized acquisition of this radioactive material is possible.
Sanitizing food and other materials
Radioactive material is also used to irradiate foodstuffs to prevent decomposition, regardless of the ambient temperature. Any food that is stable at room
temperature (this would not include items such as ice cream) can be stored on a grocery shelf instead of being placed in a freezer.
Often, the radiological source employed is an isotope of Cobalt. The arrangement of the site is usually a 20 or 30 feet deep pool situated in a concrete-walled room.
When not in use, the radiological source is lowered to the bottom of the pool by remote-control. The water absorbs the rays, allowing personnel to safely enter the
room. The room is usually built with three-feet thick concrete walls, floors, and ceiling. There are no doors at the entry and exit points, but instead, overlapping walls,
much like those for restrooms that prevent line-of-sight into the room, preventing the rays from escaping the room when the source is raised from the pool.
First, the material to be sanitized is hermetically sealed in a plastic package. The material can be foodstuffs as well as medical equipment such as blood transport
tubing used in open-heart surgery.
Then the material is transported to the radiation site and placed on a closed-loop conveyor belt that runs through the overlapped-wall opening, past the radiation
source, and out the exit. Outside the sterilization room, materials are placed on the transport belt at one station and removed at another station when the belt exits
the room.
The irradiated materials do not pick up any radiation themselves, but the rays that pass through them eliminate all biological material in the food or non-food material.
As soon as the material has run through the room, it is ready to be merchandized, sold, and consumed.
Some people do not eat irradiated food out of fear that they will receive a radiation dose, but this is not possible because the food and package do not become
radioactive. The packaging has to be of the type that does not materially change when radiated (for example, get brittle).
Some materials that are prone to becoming radioactive when exposed to a radiation source are not candidates for this type of sterilization process.
Unauthorized acquisition of this radioactive material is possible.
Power plants to feed the grid
Many countries have built nuclear power plants to generate electricity for their public power grid, notably France, which derives a relatively high percentage of its
electrical power from nuclear power generation plants.
An isotope of uranium is usually used as the power source for a nuclear power plant. Strict safety procedures are required to maintain safe operation of a nuclear
power plant.
Unauthorized acquisition of this radioactive material is possible.
Power plants to drive the Navy
Under Admiral Rickover, often called "the father of the nuclear Navy" many nuclear-powered surface vessels and submarines have been built and employed to
attempt to maintain world peace. The advantage of a nuclear power plant on an ocean-going vessel is that it requires no refueling for years.
Unauthorized acquisition of this radioactive material is improbable.
Characteristics of Radiological Substances
Half-life
The half-life of a radiological substance is the time required for the substance to lose half of its radioactivity. Radioactivity is the emission of alpha and beta particles
and gamma rays, in varying proportions, depending on the type of material. Since the supply of emitted particles and rays is not infinite within a substance, the
quantity emitted continues to decline until there are no more. At this point, the substance changes from a radioactive element or isotope to a different element,
such as lead. The half-life of an emitter can be a few seconds up to thousands of years, depending on its type, but in general, the half-life of most substances
discussed here is on the order of 30 years and up.
Radioactive material and Cells
Radioactive material is dangerous to cells because the emissions can destroy or rearrange the Diribo Nucleic Acid (DNA) which is the template that tells the cell
how to act and replicate. A single atom of radioactive material can disrupt cells, sometimes causing them to begin uncontrolled multiplication, a symptom of
cancer.
In the spectrum of radioactive material size, the most limited dispersion would be that of a single particle, for example, a rock. A radioactive rock could be placed
into a lead container and stored in a safe place. (Although many substances can prevent the passage of radioactive particles and rays, lead is a relatively available
and convenient to use for smaller items. Concrete is often used to encase larger items). At the other end of the particle size spectrum, a single atom of radioactive
material could float far from its source and be difficult to locate and place into safe storage. The more the particles are dispersed, the greater the difficulty of cleaning
them up.
Breaking radioactive material into single atoms is very difficult, and, ordinarily, can only be accomplished in million-degree temperatures created in a fission or fusion
scenario.
A less sophisticated option is to grind the material into a fine, talcum-like powder. Dispersion of a fine powder is possible, but not efficient unless the electrical charge
is removed so that the particles don't tend to clump together and quickly settle to an oppositely-charged surface. Although the methods for removing the electrical
charge on the particles are, fortunately, a closely-held secret, it has been reported that the electrical charge can be reduced by the addition of some form of
silicon.
Issues related to particle dispersion
When radioactive particles are dispersed into the air, they can travel great distances, and they can settle onto the clothing and skin or be inhaled or ingested by
people and animals. If an area is contaminated by particles that have settled, commonly known as "fallout," their emission of dangerous alpha and beta particles
and gamma rays pose a hazard to life forms.
Cleaning up these particles can be a difficult and expensive process. Personnel in the area need to wear protective clothing and breathing filters. The movement of
personnel in a contaminated area or wind currents can cause the particles to become airborne and float to another location. In some cases, it may be decided that
the best solution is to cover the area with some coating and leave it uninhabited until technology has discovered a way to clean it up or the radiation drops to a safer
level over a period of time.
This situation could be problematic in a city. It is imagined that a wall might be built around the contaminated area and some sort of grease, plastic, concrete, or
other non-water soluble material be poured onto the surfaces within the walls to contain the radioactive particles until they have decayed to the extent that they no
longer pose a hazard to life.
The health concern of ingesting Radiological Particulates
The health problems associated with airborne particulate dispersion are not immediately life-threatening. People should leave the contaminated area to reduce their
exposure, and they should be moved to a decontamination area to remove and destroy contaminated clothing. A thorough showering may be necessary for people
and items. The exit to the decontamination site should have Geiger counter monitors to ensure that all radioactive substances have been removed from persons and
material.
Depending on the situation, the people may have to depart the area quickly, leaving all of their belongings behind. Relocation centers and services will have to be set
up since the contaminated area may not be safe for habitation for a lengthy period of time.
For those persons who ingest or breathe contaminates, cancers may result, although medical technology has therapies to combat such illnesses. In the absence of
sophisticated breathing apparatuses, inhaling through a handkerchief may be a possible safety measure, depending on particulate size, until a person is clear of the
area.
Potassium Iodide (KI)
Potassium Iodide, chemical identification KI, has been discussed in the press as a way to protect people from radiation, but it only works in specific conditions. If
a dirty bomb contains radioactive Potassium Iodide, stable (not radioactive) Potassium Iodide pills or liquid can be taken to block radioactive KI to enter the thyroid gland.
Because radioactive KI goes to the thyroid gland, by taking stable KI before radioactive KI is ingested, the thyroid gland is filled with stable KI which blocks radioactive KI
from getting into it.
The Centers for Disease Control and Prevention discusses Potassium Iodide dosage. In summary,
it recommends that adults, nursing mothers, and children who weigh more than 150 lb. take 130milligrams (mg). Children of age 3 to 18 years should take 65mg.
Children 1 month to 3 years of age should be given 32mg. Newborns up to 1 month of age should be given 16mg. The CDC indicates that these dosages are good
for the first 24 hour period. After that, it recommends further dosages only be taken by direction of a medical doctor or by government recommendation. Potassium
Iodide is available without a prescription, and it can have a shelf life of up to seven years.
Although it may be a good idea to keep a supply of Potassium Iodide in an
emergency kit, if a dirty bomb does not contain radioactive Potassium Iodide, the medicine is not effective. Emergency personnel may be able to forward a
sample of dirty bomb particulates to a lab that can determine the radioactive substances it contained. Then health recommendations may be made to the
public.
Dirty bomb particles, even if propelled only by a firecracker, can be disruptive to activities in the contaminated area, but it is unlikely that they will cause many
fatalities if the populace is educated, does not panic, and has developed plans to react to such an event. The CDC has a web page that discusses
dirty bombs.