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Radiological Dispersal Devices (RDDs)



Radiological Dispersal Devices (RDDs):
Dirty Bomb, Other Dispersal Methods

  • Radiological Dispersal Device (RDD) is any device that causes the purposeful dissemination of radioactive material without a nuclear detonation.
  • Dispersion methods can be
    • "Dirty Bomb" = Explosive method of dispersion (See Figure 1)
      • Explosion produces radioactive and nonradioactive shrapnel and radioactive dust
      • Explosion causes
        • Radiation contamination, commonly (Animations)
        • Radiation exposure only in certain circumstances (Animations)
        • Physical injury
        • Burns
        • Panic, fear

      Figure 1. Dirty Bomb: Radiological Dispersal Device Using Explosive
      Dirty Bomb: Radiological Dispersal Device Using Explosive Exploding dirty bomb (RDD) Replay animation

      Adapted from:
      Armed Forces Radiobiology Research Institute
      Explosion disseminates radioactive and non-radioactive shrapnel and radioactive dust


      Figure 2. Difference between Dirty Bomb and Fission Bomb
      dirty bomb (RDD)
      Dirty bomb:
      • Explosives combined with radioactive materials
      • Detonation vaporizes or aerosolizes radioactive material and propels it into the air
      • Not a nuclear detonation
      Fission bomb example
      Fission bomb: one example
      • Caused by an uncontrolled nuclear chain reaction with uranium-235 or plutonium-239
      • This example has pyramids of plutonium with surrounding explosives
      • Initial explosion produces imploding shock wave that drives plutonium pieces inward into central sphere containing pellet of berylliu/polonium, creating "critical mass"
      • Resulting fission reaction causes bomb to explosde with tremendous force: nuclear detonation
      Sources: Adapted from Levi MA, Kelly HC. Weapons of mass disruption. Sci Am. 2002 Nov;287(5):76-81. [PubMed Citation]

    • Other Dispersal Methods
      • Passive or active dispersion of unsealed radioactive sources, e.g., deposit in soil or water, drop from airborne device (See Figure 3)
      • Radioactive sources can be solid, aerosol, gas, or liquid
      • Contamination of people may occur via air, water, soil, or food

      Figure 3. Dispersal of Radioactive Material by Aircraft
      Dispersal of radioactive material by aircraft Replay animation


  • Explosive RDDs cannot cause mass casualties on the scale of a nuclear explosion. All or most fatalities or injuries will probably due to explosion itself.
  • While large numbers of people in a densely populated area around the detonation of an RDD might become contaminated and require decontamination, few if any will be contaminated to a level that requires medical treatment.
  • Local health authorities will have to assess the persons who were very close to the point of release for the need for medical intervention.
  • The health and environmental consequences from RDDs, will depend on
    • The design of the device
    • Type and quantity of radioactive material
    • The pattern of dispersion following the release
  • RDDs may affect
    • Small, localized areas (e.g., a street, single building, or city block)
    • Large areas, up to several square miles, depending on the nature of the dispersion and the amount and type of radioactive material
  • Other hazards may also be present
    • Fire, smoke, shock, shrapnel (from an explosion)
    • Industrial chemicals
    • Secondary device
  • Radioactive decontamination of persons and areas affected may be required.
References:

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Potential Isotopes Used in RDDs


RDD Isotope Fact Sheets

 
Isotope
More Information: Fact Sheets
EPA***

Americium-241

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Californium-252

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Cesium-137

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Cobalt-60

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Iridium-192

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Plutonium-238

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Polonium-210

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Radium-226

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Strontium-90 (Sr-90/Y-90)

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*    HHS/Centers for Disease Control and Prevention
**  HHS/Agency for Toxic Substances and Disease Registry
***Environmental Protection Agency

 
See also:
Radioactive Properties, Internal Distribution, and Risk Coefficients (PDF - 2.34 MB) (Human Health Fact Sheet, Argonne National Laboratory, August 2005)
Radiological and Chemical Fact Sheets to Support Health Risk Analyses for Contaminated Areas (PDF - 2.34 MB) (Argonne National Laboratories, 2007)
Physical, Nuclear, and Chemical Properties of Plutonium (Institute for Energy and Environmental Research)


Basic Radiological Properties of RDD Isotopes


Basic Radiological Properties of Nine Key Radionuclides for RDDs

Isotope

Half-Life
(years)

Specific Activity
(Ci/g)

Decay Mode

Radiation Energy (MeV)

Alpha
(α)

Beta
(β)

Gamma
(γ)

Americium-241

430

3.5

α

5.5

0.052

0.033

Californium-252

2.6

540

α (SF, EC)

5.9

0.0056

0.0012

Cesium-137

30

88

β, IT

-

0.19, 0.065

0.60

Cobalt-60

5.3

1,100

β

-

0.097

2.5

Iridium-192

0.2 (74 d)

9,200

β, EC

-

0.22

0.82

Plutonium-238

88

17

α

5.5

0.011

0.0018

Polonium-210

0.4 (140 d)

4,500

α

5.3

-

-

Radium-226

1,600

1.0

α

4.8

0.0036

0.0067

Strontium-90

29

140

β

-

0.20, 0.94

-

SF = spontaneous fission; IT = isomeric transition; EC = electron capture. A hyphen means not applicable. The radiation energies for cesium-137 include the contributions of barium-137 metastable (Ba-137m), and those for strontium-90 include the contributions of yttrium-90.

Adapted from Radiological Dispersal Device (PDF - 2.34 MB) Human Health Fact Sheet, Argonne National Laboratory, August 2005

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Potential RDD Effects

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Guidance about Initial Protective Actions after an RDD Explosion

  • Musolino SV, Harper FT, Buddemeier B, Brown M, Schlueck R. Updated Emergency Response Guidance for the First 48 H after the Outdoor Detonation of an Explosive Radiological Dispersal Device. Health Phys 2013;105(1);65-73.
    • See photo of radioactive dispersal from an experimental RDD explosion.
    • See diagram of hypothetical dispersal possibilities.
    • This important paper updates an earlier version from 2006. It uses experimental and modeling data to provide guidance about the "predicted range of radioactive ballistic fragments that could endanger first responders and the public."
    • See diagram of recommended initial Protective Action Zones from this paper.
      • Before definitive environmental radiation measurements are performed, the authors recommend that incident managers establish an empiric "initial hazard boundary corresponding to the potential for acute health effects" of "250 meters in all directions from the site of the incident". This is smaller than the 500 meter boundary recommended in the authors' previous paper from 2006. Subsequent actual measurements may alter these perimeter recommendations.
      • "This boundary is independent of the total activity of the radioactive material." It reflects confidence that debris from radioactive ballistic fragments would likely fall within 250 meters of the explosion.
      • The authors also recommend a "wider initial Shelter-in-Place Zone, 500 meters in all direction from the incident site and 2,000 meters downwind." This will diminish the chance of "encountering the undiluted aerosol plume and hence an acute exposure from inhalation (if the device generated significant aerosol, shine from a highly radioactive fragment, or injury from the detonation of a secondary improvised explosive device".
      • "Persons who are outside, or in s significantly damaged or 'smoky' building, should immediately move to the nearest robust, intact structure; if the event is a small one, people should move out of the immediate area provided that there is a clear path but still take shelter in an intact nearby building."
      • "In both cases, people should remain in the shelter until the local officials direct them to proceed to an uncontaminated evacuation route, and downwind of the detonation site, sheltering should be extended out to 2,000 meters to avoid a lower level exposure to the aerosol plume."
    • The paper also discusses aerosol dispersal.
      • "The assessment of the potential range and effects of dispersal from small particles as aerosol remains unchanged from guidance issues in 2006."
      • The article provides more detailed guidance about this kind of complex radioactive aerosol dispersal from various kinds of scenarios, and how to provide response guidance based on these measurements.
    • The paper also provides detailed guidance for how to take measurements for evaluating the level and location of the radiation contamination after an RDD explosion.

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Other Guidance about Radiation Control Zones and Perimeters after a Radiological Incident

  • A variety of professional organizations and government entities have proposed Radiation Control Zones and Perimeters after a radiological incident based on actual measurements of environmental radiation levels.
  • These zones are recommended to help protect responders and the public, and they are often linked to Protective Actions.
  • Note that the labels of the zones, the radiation levels circumscribed by the boundaries, and the colors assigned to the zones are not the same for each organization.
    • This table and its links to diagrams provide examples of several groups' proposed Radiation Control Zones for Radiological Incidents and show the many differences among the agencies.
    • Responders should know and adhere to the nomenclature used by their agency.
  • Note that zone designations for nuclear incidents are likely to be different from zone designations for Radiological Incidents.
  • Managing a Bombing Incident: First Bomb App (DHS):

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Communicating with the General Public after an RDD

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References

Basic Information about RDDs

US National Laboratory Guidance

HHS Guidance

NCRP Guidance

Technical Guidance

  • U.S. Department of Energy, Federal Radiological Monitoring and Assessment Center. Monitoring manual volume 1; operations. Washington, DC: U.S. DOE; DOE/NV/25946-1554; July 2012.
  • U.S. Department of Transportation, Pipeline and Hazardous Materials Safety Administration, Emergency response guidebook. Washington, DC: U.S. DOT; 2012.

Response Guidance for Local Responders and Health Care Entities


 

US Department of Health & Human Services     
U.S. Department of Health & Human Services Office of the Assistant Secretary for Preparedness and Response National Library of Medicine