A radioactive 'dirty bomb' would probably cause more panic than mass destruction, but the economic fallout could be enormous, experts said June 10, 2002. U.S. Attorney General John Ashcroft said authorities had arrested an al Qaeda operative who was planning to build such a device, which is a conventional bomb -- even dynamite -- combined with radioactive material.

The following two models were generated by the American Federation of Scientists using governmental data show two types of "dirty bombs". They state the immediate threat from radiation would be small but that extensive cleanup would be required as well as possible evacuation to guard against long-term exposure.

Significant amounts of radioactive materials are stored in laboratories, food irradiation plants, oil drilling facilities, medical centers, and many other sites. Cobalt-60 and cesium-137 are used in food disinfection, medical equipment sterilization, and cancer treatments. However, it must be noted that nearly 1500 pieces of radioactive materials have been lost or stolen since 1996.

Potential Damage Caused by a 'Dirty Bomb'

In both cases below, it is assumed that the dirty bomb is released on a calm day (wind speed of one mph) and that the material is distributed by an explosion causing a mist of fine particles to spread downwind in a cloud. People will be exposed to radiation in several ways.

* Through dust inhaled during initial passage of the radiation cloud, if people have not escaped the area before the dust cloud arrives. This scenario also assumes about 20% of the material is in particles small enough to be inhaled. Material containing either cesium or colbalt will stay in the body and lead to long term exposure.

* Anyone living in the affected area will be exposed to material deposited from the dust that settles from the cloud. If the material contains either cesium or colbalt (gamma particles), residents will be continuously exposed to radiation from this dust. If the material contains americium (alpha particles), dust that is pulled off the ground and into the air by wind, automobile movement, or other actions will continue to be inhaled, adding to exposure.

* In a rural area, people would also be exposed to radiation from contaminated food and water sources.

The contamination area depicted here is based on using 10 pounds of TNT and only a pea-size bit of cesium-137 which could be found in a medical gauge. Initial casualties are limited to the site of the explosion.

Assuming 30 years' exposure:

Inner ring: 1 cancer death per 100.
Middle ring: 1 cancer death per 1000.
Outer ring: 1 cancer death per 10,000.


This scenario uses a 1 x 12" or "pencil" rod of cobalt-60, like that typically found in a food irradiation facility. Slightly smaller sizes could be found in research institutions. If exploded in the same area as the graphic above, the result would be much more deadly. However, cobalt is harder to obtain and use. In this scenario, there is a higher level of
contamination. It would be decades before the city was inhabitable again, and demolition might be necessary. If such an event were to take place in a city like New York, it would result in losses of potentially trillions of dollars.

Assuming 30 years' exposure:
Inner ring: 1 cancer death per 100, but may be as high as 1 in 30.
Middle ring: 1 cancer death per 1000.
Outer ring: 1 cancer death per 10,000.

NOTE: Average cancer risk is 2,000 in 10,000 or 20%.
SOURCE: http://www.fas.org/faspir/2002/v55n2/dirtybomb.htm

Dirty Bomb Detector
A 10-pound, battery-powered hand held detector that promises to bring state-of-the-art radiation spectrometry anywhere radioactive materials are found, developed by the Lawrence Berkley National Laboratory is pictured in this undated file photograph. Long before September 11, engineers at Lawrence Berkeley National Laboratory, in collaboration with researchers at Lawrence Livermore and Los Alamos National Laboratories, have been working to outsmart individuals attempting to smuggle radioactive material into the country. This hand held device can detect these
isotopes which could be used to build conventional bombs laden with radioactive material - a so-called dirty bomb. REUTERS/Lawrence Berkeley National Lab/Handout

NRC Warns of Nearly 1,500 Pieces Missing of Radioactive Materials

May 4, 2002; Page A13
Washington Post

U.S. businesses and medical facilities have lost track of nearly 1,500 pieces of equipment with radioactive parts since 1996, according to a new federal accounting of radiological material that terrorism experts warn could be used in a "dirty bomb" attack against a U.S. city.

The loss of radiological material, ranging from medical diagnostic equipment to industrial X-ray machines, has been viewed with increased concern since the Sept. 11 terrorist attacks and has prompted several new measures to prevent theft, the Nuclear Regulatory Commission said in a document released yesterday by a House member from Massachusetts.

The vast majority of the missing items contain tiny amounts of radioactive material and pose little threat, NRC officials said. But there have been several instances in recent years of lost or stolen hospital equipment that contains potentially lethal amounts of radioactive cobalt or cesium.

Such material could be packed around a conventional explosive -- a combination known as a "dirty bomb" -- to scatter radiation over large areas.

"The commission is concerned about this potential terrorist threat and has advised its licensees to enhance security," the NRC said in the report, which was requested by Rep. Ed Markey (D-Mass.).

The NRC regulates the commercial use of radioactive material. It acknowledged receiving reports of 1,495 lost or stolen radioactive "sources" between October 1996 and September 2001; about 660 of the missing items -- 44 percent -- were recovered, but the rest remain missing, the agency said.

"If one of these things can end up in a scrap yard, it can end up in the hands of a terrorist," Alvarez said.

read full article: http://www.washingtonpost.com/ac2/wp-dyn?pagename=article&node=&contentId=A29869-2002May3&notFound=true