TA-ANALYSIS: DHS - Safe Levels For "Dirty Bomb" Exposure To Be Raised

NPR are reporting that the Department of Homeland Security is proposing to raise the level of radiation exposure considered safe for contaminated members of the public and emergency workers.
Guidelines are to be issued that would recommend evacuation of residents only if radiation levels rise to the equivalent of 1,000 dental X-rays, or about 1 rem.
The new Department of Homeland Security guidelines suggest that the radiation dangers from a dirty bomb are not as great as many emergency services have previously thought.



It does seem a bit strange that it has taken until now for these guidelines to be issued, as the threat of a dirty bomb has been evident since 2001.
How the authorities are to persuade residents to stay put after a dirty bomb attack is another matter. How on earth do you reassure a sceptical public that the radiation levels do not warrant evacuation, particularly as the main danger is presented by airborne radioactive particles that are easily inhaled?
Whether the new recommended radiation safety levels for emergency workers and residents are an accurate estimation of the danger to health is going to cause much debate.

[edit on 7-28-2004 by Valhall]

Actually, the residents in the immediate vicinity of a dirty bomb explosion would not be aware of the contamination unless they had a film badge or geiger counter. A dirty bomb does not have the stereotypical mushroom cloud, high winds, etc normally associated with standard nuclear weapons designed for air, surface or sub-surface detonation. A dirty bomb consists of radioactive by-products combined with conventional explosives leaving an area contaminated. It might be useful for denying terrain to the enemy for a prolonged period of time without the blast, shock, illumination and high winds resulting from a "nuclear detonation".

FormerFed wrote

Actually, the residents in the immediate vicinity of a dirty bomb explosion would not be aware of the contamination unless they had a film badge or geiger counter.

They will soon become aware that a dirty bomb has exploded by the presence of emergency workers wearing protective equipment...or are you suggesting that the authorities might not inform residents of the presence of airborne radioactive particles.


zero lift

Actually the overall risks from a dirty bomb are rather low. The psychological effect would be greater than the physical risks.

First of all, you have to consider the nature of the material. Even if your bomb design was successful at converting the radioactive material to an airborne dust or fume, said dusts or fumes will not go very far. Why? Because most of the common radioactive elements are heavy. They will setle out, plate out of the atmosphere rather quickly.

Back in the 60�s, the A USAF bomber refueling over the coast of Spain collided with the tanker plane. There were three bombs on board. One fell into the sea and was later recovered. The other two broke up over the farm fields. The U.S. spent a lot of time and money cleaning up the area, but clean it up they did.

Secondly, it would be rather difficult to handle a sufficiently large enough quantity of material that would be required to create a widespread contamination problem.

In that case your bomb maker would indeed be a suicide bomber.

HowardRoark wrote

First of all, you have to consider the nature of the material. Even if your bomb design was successful at converting the radioactive material to an airborne dust or fume, said dusts or fumes will not go very far. Why? Because most of the common radioactive elements are heavy. They will setle out, plate out of the atmosphere rather quickly.

If the radioactive material used was already in fine powder form it will travel a lot further than you think. The Chemical Defence Experimental Establishment Porton Down have in the past conducted ground level experiments with wind-borne 1-5 microns sized particles and easily managed to disperse them from inside a major city (Bristol) to sampling units based over 80 kilometres away from the source.

Also, the material could be easily dispersed in an underground Metro network. The material will travel many tens of miles on such a system.
If such an attack occurred in a major city the psychological damage would be in second place to the actual damage caused by physical loss of infrastructure.


zero lift

That is a big "if."

Most radioactive material commonly out there is NOT in powder form, and it is not easily converted to powder form.

HowardRoark wrote

That is a big "if."................................Most radioactive material commonly out there is NOT in powder form, and it is not easily converted to powder form.

Maybe the "if" is not quite as big as you think, HowardRoark.

www.iaea.or.at...< br />
In the Goi�nia incident, authorities believe that scavengers dismantled a metal canister from a radiotherapy machine at an abandoned cancer clinic and left it in a junkyard. During the dismantling procedure the metal capsule that contained the caesium-137 source was ruptured. Over the next week, several hundred people in Goi�nia were exposed to the caesium-137, but did not know it. Some children and adults, thinking the caesium powder was "pretty," even rubbed it over their bodies. Others inadvertently ate food that had been contaminated with the radioactive powder. After one week, a public health worker correctly diagnosed radiation syndrome when a sufferer visited a clinic. The Brazilian Nuclear Energy Commission sent in a team and they discovered that over 240 persons were contaminated with caesium-137, four of whom later died. The accident also contaminated homes and businesses and this required a major clean-up operation.

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U.N. Says Materials for Dirty Bomb Easy to Find

Materials for a dirty bomb are indeed very easy to get because they do not have to be nuclear.However, it is true that much nuclear material, some dangerous and some not, are available in avery unregulated way.The United Nations nuclear watchdog Tuesday warned that radioactive materials needed for a"dirty bomb" could be found in almost every country and more than 100 states had inadequatecontrols to prevent their theft

Monday, the IAEA told Reuters a priority would be to recover large quantities of caesium-137, a radioactive powder the Soviets used to keep grain from rotting. A small amount could be deadly if used in a dirty bomb.In 1987, a canister of caesium abandoned in a junkyard in Brazil contaminated 240 people, fourof whom later died

In 1996, Chechen rebels placed a container with the powder in a Moscow park. Fortunately, it was never dispersed.

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www.abc.net.au...

Last Update: Saturday, May 8, 2004. 1:06am (AEST)
Ukraine secret police seize radioactive caesium
Ukraine's SBU secret service arrested three people and seized two cases containing highly-radioactive caesium-137, the SBU's press service said.

Nuclear experts say caesium powder would be ideal for a so-called "dirty bomb", a conventional explosive laced with radioactive material.

They say such bombs would cause more fear and panic than physical damage.

The three men from the southern Sevastopol region were trying to sell the two cases with caesium for $US120,000.

Caesium is a highly-toxic radioactive substance that can explode in very cold water but is used in agriculture and in atomic clocks.

"Buyers and sellers were caught as they were trying to sell the containers. A criminal case was launched," the SBU said in a statement.

"An investigation showed cases contained caesium-137 which poses a real threat to the life and health of people."

Officials gave no other details.

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www.enn.com...

U.N. nuclear agency gets little access in Iraq
Tuesday, June 03, 2003
By Louis Charbonneau, Reuters

The U.N. International Atomic Energy Agency (IAEA) is due to head back to Baghdad Friday to probe reports of looting at the Tuwaitha Nuclear Research Center, Iraq's biggest nuclear site. But they are not allowed on to the main plant.
There were more than 500 tons of natural uranium and 1.8 tons of low-enriched uranium stored at Tuwaitha as well as smaller amounts of highly radioactive caesium, cobalt, and strontium
Inadequate Control of World's Radioactive Sources - IAEA Press Release 02/09
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Radioactive powder is out there , and does get into the hands of unauthorised hands. There is every likelyhood that a determined terrorist group can and will obtain large enough quantities of radioactive powder to make many dirty bombs.
In the US, even Boy Scouts have been proved to have the ability to scavenge radioactive powder.

www.findarticles.com...

The radioactive boy scout: when a teenager attempts to build a breeder reactor - case of David Hahn who managed to secure materials and equipment from businesses and information from government officials to develop an atomic energy radiation project for his Boy Scout merit-badge.

...............On November 29, state radiological experts surveyed the potting shed. They found aluminum pie pans, jars of acids, Pyrex cups, milk crates, and other materials strewn about, much of it contaminated with what subsequent official reports would call "excessive levels" of radioactive material, especially americium-241 and thorium-232. How high? A vegetable can, for example, registered at 50,000 counts per minute--about 1,000 times higher than normal levels of background radiation. But although Minnaar's troops didn't know it at the time, they conducted their survey long after David's mother, alerted by Ken and Kathy and petrified that the government would take her home away as a result of her son's experiments, had ransacked the shed and discarded most of what she found, including his neutron gun, the radium, pellets of thorium that were far more radioactive than what the health officials found, and several quarts of radioactive powder. "The funny thing is," David now says, "they only got the garbage, and the garbage got all the good stuff."


zero lift

It is true that there are a number of radioactive substances out there, and some of them are relatively easy to obtain. However, most of these are available as relatively small quantities of material or as large quantities of low level materials. For all practical purposes, a �dirty bomb� is a rather ineffective weapon. Pound for pound, you could do much more damage with a couple of oxygen cylinders and a tank of propane.

In addition, I suspect that the vast majority of the suicide bombers out there do not make their own bombs, someone else does that and sends them on their way. The bomb maker is protected for his skill and knowledge.

You would not have that protection with a dirty bomb. From the instant such a project were started it would be a suicide mission by all involved. Not that the terrorists haven�t demonstrated this tendency already, It just will be a difficult task none the less.

HowardRoark wrote

You would not have that protection with a dirty bomb. From the instant such a project were started it would be a suicide mission by all involved

That's a very good point Howard but a simple dirty bomb can be made by mixing a few ounces of radioactive powder with a large firework. The firework is used to disseminate the powder. Assembling a simple device like this is well within most people abilities. There is no need for an expert bombmaker to be involved. The radioactive powder would be supplied in a protective container and only mixed at the last moment by the bomber.

This device would be particularly effective in a large enclosed space such as a metro system. The metro carriages would themselves enable the airborne particles be distributed around the system. The disruption an attack of this nature would cause would be immense as would the cost of decontamination of the metro system.


zero lift

OK, let�s say you set off a firework mixed with a radioactive powder in a subway system.

What next. If you do it in the middle of the night, Maybe no one will see it, but then again, what if some one does? Metal particulates dispersed in this manner tend to be �sticky.� They are also heavy, the will settle out and plate out on the walls, ceilings and floors of the tunnel. Have you ever been in a subway tunnel? One thing they all have in common is that they are damp. Any moisture condensed on the sides of the tunnel will further work to limit the dispersal of the dust.

If you set off your firework in the middle of rush hour, it is probable that someone will see it. What then? Fires in subway systems can be serious issues. If the fire alarm system is set off by the resultant smoke you can bet that all of the subway traffic will be immediately halted.

Granted the Japanese subway attacks proved that these venues are vulnerable to this sort of attack, but far more damage was done by the Madrid train bombings.

Again, I do not want to downplay this threat, but overall, I think that there is more of a scare factor at work here than actual risks.

During 1963-1964 Porton Down conducted experiments on the London Underground to discover how far particulates would travel around the Tube system. The experiments were part of "sabotage" trials that Porton were conducting at various vulnerable locations in the UK.

It was decided to reflect clandestine types of activity by placing the powder in a conventional cardboard face powder carton. This was held together in such a way as it burst when dropped from the window of a train. The carton was dropped by a London Transport Executive trainee engineer, who did not know it's real purpose.

During 1964, the trials were repeated and it was found that the particles travelled many tens of miles in amounts that would have seriously contaminated the system should the particles have been toxic. In particular the trials proved that the trains themselves would have carried the particles vast distances.

So if necessary, a dirty device doesn't necesarily have to be a bomb, thus ensuring maximum contamination of a system before the authorities realise an incident has taken place.


zero lift