Homeland Security Planning Scenarios

Radiological Attack - Radiological Dispersal Devices

Summary

Scenario Overview:

General Description - Cesium-137 (137Cs) has a half-life of 33 years. It decays by both beta and gamma radiation. It is one of several known radioactive isotopes that stand out as being highly suitable for radiological terror. This isotope causes skin damage similar to burns, but the injury may be as deep within the body as on the skin. Cesium would be particularly dangerous if accidentally ingested or inhaled, even in small quantities. Cesium mimics potassium in the body. It binds to concrete and other masonry, making decontamination of such buildings extremely difficult and possibly economically infeasible. Use of 137Cs in an urban setting would seriously raise the cost of cleanup.

137Cs is mostly used in the form of cesium chloride (CsCl), because it is easy to precipitate. CsCl is a fairly fine, light powder with typical particle size median at about 300 microns. Fractions below 10 microns are typically less than 1%. In a Radiological Dispersal Device (RDD), most will fall out within approximately 1 to 2,000 feet (although many variables exist), but a small amount may be carried great distances, even hundreds of miles.

In this scenario, the Universal Adversary (UA) purchases stolen CsCl to make an RDD or "dirty bomb." The explosive and the shielded 137Cs sources are smuggled into the country. Detonator cord is stolen from a mining operation, and all other materials are obtained legally in the United States. Devices are detonated in three separate, but regionally close, moderate-to-large cities. The cities are physically similar with geographic topography that is flat. The results in each city are essentially the same. The contaminated region covers approximately thirty-six blocks in each city and includes the business district (high-rise street canyons), residential row houses, crowded shopping areas, and a high school. Buildings in the affected areas are principally made of concrete and brick; some are stone faced.

The entire scene is contaminated with 137Cs, though not at levels causing immediate concern to first responders. Due to the size of the explosion, the radioactive contamination is blown widely such that the ground zero area is not as radioactive as might have been expected. The detonation aerosol contains 90% of the original 137Cs source with radioactive particles whose sizes range from 1 micron (or micro-meter, µm) to 150 microns - the size of most of the particles is approximately 100 microns. Larger particles either penetrate building materials in the blast zone, or drop quickly to the ground as fall-out within about 500 feet.

Variable winds of 3 to 8 miles per hour carry the radioactively contaminated aerosol throughout an area of approximately thirty-six blocks (the primary deposition zone). Complex urban wind patterns carry the contamination in unpredictable directions, leaving highly variable contamination deposition with numerous hot spots created by wind eddies and vortices. Radioactivity concentrations in this zone are on the order of 5-50 microµi/m2, with hot spots measuring 100-500 microµi/m2; however, traces of the 137Cs plume carry more than 3.5 kilometers (~ 2.2 miles) on prevailing winds. Air intakes contaminate interiors of larger buildings, and negative indoor building pressure draws contaminated aerosol into buildings via cracks around windows and doors. In city one, the subway air intakes contaminate the subway system.

Timeline/Event Dynamics - The attacks have no advance notice or intelligence that indicates their possibility. The explosions are instantaneous, but plume dispersion continues for 20 minutes while breezes navigate the complex environments before particles have fully settled. First responders do not recognize radioactive contamination for 15 minutes in city one. The explosions in cities two and three are promptly identified as "dirty bombs" - this provides some advantage to first responders and government officials in managing contamination on-scene, and in communicating with the public concerning topical contamination and spread of contamination.

Secondary Hazards/Events - Small fires from ruptured gas lines occur in the vicinity of the blasts. Unstable building facades, rubble, and broken glass create physical hazards for rescue workers. Small amounts of lead, asbestos, and Polychlorinated Biphenyls (PCBs) are present in the air and on surfaces. Human remains present a biohazard, and some of these are very radioactive.

Key Implications:

At each site, the blast results in 180 fatalities and about 270 injured requiring medical care. In addition, up to 20,000 individuals in each primary deposition zone potentially have detectable superficial radioactive contamination.

In each blast, one building and twenty vehicles are destroyed, and eight other buildings suffer varying degrees of damage, such as minor structural damage and broken windows. Radioactive contamination is found inside and outside of buildings over an area of approximately thirty-six blocks in each city. Minor contamination may be an issue further downwind as investigators perform more thorough surveys. Most of the subway system in city one is contaminated.

Over the long term, decontamination efforts are expected to be effective, but some property owners choose demolition and rebuilding. Many square blocks will be unavailable to businesses and residents for several years until remediation is completed.

Transportation is severely hampered in each city. Bus, rail, and air transport routes are altered, and officials build highway checkpoints to monitor incoming traffic for contamination. The subway system in city one is completely closed for an extended period. Hospitals in each region, already at maximum capacity with injuries from the blasts, are inundated with up 50,000 "worried well."

The sewage treatment plant is quickly contaminated. Seventy-five businesses are closed for an extended duration while radioactive contamination is remediated. Local tax revenues plummet, and people discover that insurance claims are rejected. The schools in the contamination zones are closed and students meet in alternate locations. Nearby towns and cities close their doors to residents of the impacted cities for fear of contamination spread.

Decontamination, destruction, disposal, and replacement of lost infrastructure will be costly (i.e., hundreds of millions of dollars per site). The entire contaminated area may be economically depressed for years. An overall national economic downturn may occur in the wake of the attack due to a loss of consumer confidence.

In the long term, no one will suffer acute radiation syndrome, but approximately 20,000 individuals are likely to become externally contaminated at each site. Low-level contamination may enter food and water supplies. The sum of the cumulative exposures results in an increased lifetime cancer risk proportionate to the dose. Mental health services will be required.

Mission Areas Activated:

Prevention/Deterrence/Protection - Efforts should include prevention of trafficking and importation of CsCl and weapon components, detection of the plot, reconnaissance of the site, protection, and deterrence measures.

Emergency Assessment/Diagnosis - First responders are likely to be contaminated. The downwind aerosol dispersion will be a significant component of the hazard. Assessment and coordination efforts required are numerous.

Emergency Management/Response - Actions required include mobilizing and operating incident command; overseeing victim triage; stabilizing the site; cordoning the site and managing and controlling the perimeter; providing notification and activation of special teams; providing traffic and access control; providing protection of at-risk and special populations; providing resource support and requests for assistance; providing public works coordination; providing direction and control of critical infrastructure mitigation; and providing pubic information, outreach, and communication activities.

Incident/Hazard Mitigation - Actions required include isolating the incident scene and defining the hazard areas, building stabilization, providing fire suppression, conducting debris management and radioactive and hazardous contamination mitigation, decontaminating responders and equipment as well as local citizens, and conducting local site contamination control.

Public Protection - Sheltering and/or evacuation of downwind populations will be required and must occur quickly. Protection actions required range from developing protective action recommendations and communicating them to the public to making radio-protective pharmaceutical decisions and efficiently distributing drugs.

Victim Care - Injured people will require some decontamination in the course of medical treatment and, if possible, prior to hospital admission. Thousands more will likely need superficial decontamination, and both short-term and long-term medical follow-ups.

Investigation/Apprehension - Actions required include dispatching personnel, conducting site cordoning and control, collecting field data and witness interviews, and performing tactical deployment and apprehension of suspects. Reconstruction of the attack should occur.

Recovery/Remediation - The extent of contamination will be a major challenge because 137Cs is highly water-soluble and is chemically reactive with a wide variety of materials, including common building materials such as concrete and stone. Several buildings (those most damaged) will be torn down and eventually rebuilt. Decontamination activities are undertaken for building exteriors and interiors, streets, sidewalks, and other areas.