epr-method (2003) - IAEA Publications - International Atomic Energy ...

Explosive radiological dispersal device (RDD)
Description
An RDD 97 has been or may be used to spread radioactive material or has been located before detonation.
Potential hazards
The greatest threat comes from the direct effects of an explosion rather than from radiation exposure or contamination.
The greatest radiological hazard comes from inadvertent inhalation or inadvertent ingestion of the material dispersed
by an explosion or fire or from handling radioactive debris or material in an unexploded device. There would only be a
negligible radiological threat if less than dangerous quantities (see Appendix 8) are involved. An RDD containing
quantities 10 or more times the criteria in Appendix 8 for a dangerous source would be required to result in dispersal of
material that is life threatening to unprotected people. The inhalation hazard is probably limited to the plume (e.g.
within the smoke) within 100 metres of the source of the release. Resuspension of Pu on the ground could be
hazardous near the source. External contamination is probably not hazardous but inadvertent ingestion (e.g. by putting
hands in the mouth) of contamination could be hazardous. Limited stays near the source in an unexploded RDD or
large pieces of debris by response personnel should not be hazardous but holding such material could produce injuries
in minutes. Fire fighters are generally equipped with respiratory protection that provides good protection against the
inhalation hazard. Common radiation survey instruments can detect significant external exposure hazards but cannot
detect significant inhalation hazards. There can be significant adverse and inappropriate public reaction (see Element
A11.2) and economic consequences if public and financial institution concerns are not promptly addressed. Excess,
radiation induced, cancers should not be detected following this type of emergency, even for emergencies involving
large amounts of radioactive material.
Emergency response
Incident commander 96 (lead first responder):
— Observe from a distance and assess all possible hazards- be aware of the potential for other
bombs/devices/threats.
— Approach from upwind.
— Save lives and prevent/treat serious injuries before conducting radiological monitoring.
— Deal with the conventional hazard; request assistance from bomb experts (do not handle the
device).
— Conduct immediate field assessment for indications that the device may be radioactive:
• Was a threat received in advance?
• Is there a message at the scene?
• Radiation symbol? (Not a reliable indicator)
• Gamma radiation levels significantly above background (> 1 µSv/h)98
— Prepare for bobby traps, a second devise intended to injure responders, a second devise
intended to injure evacuees.
— Activate response using the ICS (see Appendix 13) co-ordinated under an incident commander
near the scene. Establish the incident command post upwind 99 , at a safe distance and in a secure
area.
— If radiological terrorism is suspected/confirmed:
• establish an inner-cordoned area (safety distance) in accordance with Appendix 5 (Table A5-I).
• request assistance from law enforcement responders;
• avoid the smoke or use standard inhalation protection while in the smoke; and ensure those approaching scene
take action to prevent inadvertent ingestion of contamination (e.g. wear gloves, do not smoke- or eat).
• request assistance from radiological assessor (see Element A9.1);
• only approach the device or debris to protect lives until radiological assessment is performed; keep time in the
immediate vicinity (< 1 m) of device to a minimum;
97 A bomb containing radioactive material. The conventional bomb is used as a means to spread radioactive contamination.
This includes unsophisticated improvised nuclear devices (INDs) that are not expected to result in a significant yield.
98 There could be a significant radiological hazard even if gamma dose rates are at about background level (e.g, from Pu).
99 Wind direction is often very variable especially in an urban area, thus this is a secondary concern.
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