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Radiological Exposure Devices (REDs)

Radiological Exposure Devices (REDs) = Hidden Sealed Radioactive Source

  • Definition of Radiological Exposure Device
  • Causes exposure (Animations) but NOT usually contamination
  • Example: hiding a hidden radioactive source on a subway or in a sports arena, where people would unknowingly receive radiation exposure (See Figure 1)
  • Dose from exposure and specific effect on people would depend on the following factors:
    • Source properties: isotope, activity, amount, type of containment (does it attenuate?)
    • Proximity of each person to the source; is there directionality of the source
    • Length of time people were in proximity to the source
    • Whether a person's whole body or only a portion of the body received exposure

    Figure 1. Hidden Sealed Radioactive Source (Radiological Exposure Device) in Train Car

    150 Ci Iridium-192 Source Under Seat

    Hidden sealed radioactive source in metro car: 150 Ci iridium source under seat Replay animation


    Ci = curie; R = roentgen; Γ constant = 4.69 R-cm2/mCi-hr.

    Note: This graphic describes radiation exposure rate (in air) in units of R/Hr. For gamma radiation, this is roughly equivalent to a radiation absorbed dose rate in units of cGy/hour, which must also take into account any shielding present, e.g., material in the seats in this example. The casement of the source may provide directionality, attenuation, scatter preference and knowledge of this will allow for better dosimetry assessments.

References:
  1. Responding to an RDD / RED Emergency: the HHS Playbook, guidance for executive decision makers within the Department of Health and Human Services (HHS) in the event of an actual radiological terrorist attack in a U.S. city. (HHS/ASPR, April 2010)
  2. Radiation Exposure Device information sheet for the general public (HHS/CDC)
  3. The Regulation and Use of Radioisotopes in Today’s World (PDF - 1.1 MB) (NRC, April 2020)
  4. Radiological Sources of Potential Exposure and/or Contamination (PDF - 3.1 MB) (US Army Public Health Center, TG-238, January 2020)
    • This document provides details about radioisotopes of potential concern and where they are used. It updates the TG-238 document from 1999.

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