Updated Emergency Response Guidance for the First 48 h after the Outdoor Detonation of an Explosive Radiological...

This paper updates portions of the guidance originally published in 2006 based on the interpretation of subsequent experiments simulating explosive aerosolization from a radiological dispersal device and three-dimensional modeling of a high-rise urban-canyon type environment and wind field. These new data increase confidence about the predicted range of radioactive ballistic fragments that could endanger first responders and the public. The results of the most recent complete set of experiments indicate that the previously recommended initial hazard boundary corresponding to the potential for acute health effects can be reduced from 500 m to 250 m. This revised recommendation is independent of the total activity of the radioactive material. The assessment of the potential range and effects of dispersal from small particles as aerosol remains unchanged from the guidance issued in 2006. New recommendations are offered on sheltering versus evacuation and how to conduct the initial field measurements so as to make early decisions on protecting the public and responders, and providing coherent data for an assessment scientist to make a first estimate of the source term in the device.