If dispersal occurs from an explosive radiological dispersal device, first responders need to know what actions they need to take to protect life and property. Many of the decisions required to minimize exposure will be made during the first hour. To help the first responder decide what countermeasures to employ, Sandia National Laboratories has established realistic hazard boundaries for acute and sub-acute effects relevant to radiological dispersal devices. These boundaries were derived from dispersal calculations based on the aerosolization behavior of devices tested in the Sandia Aerosolization Program. For 20 years, the Sandia Aerosolization Program has performed explosive and non-explosive aerosolization tests relevant to radiological dispersal devices. This paper discusses (1) the method and technical bases used to establish hazard boundaries and the appropriate actions that apply within those areas and (2) whether large-scale evacuations or sheltering in place are appropriate responses to a radiological dispersal device event.
Strategies and decisions to protect emergency responders, the public, and critical infrastructure against the effects of a radiological dispersal device detonated outdoors must be made in the planning stage, not in the early period just after an attack. This contrasts with planning for small-scale types of radiological or nuclear emergencies, or for a large-scale nuclear-power-type accident that evolves over many hours or days before radioactivity is released to the environment, such that its effects can be prospectively modeled and analyzed. By the time it is known an attack has occurred, most likely there will have been casualties, all the radioactive material will have been released, plume growth will be progressing, and there will be no time left for evaluating possible countermeasures. This paper offers guidance to planners, first responders, and senior decision makers to assist them in developing strategies for protective actions and operational procedures for the first 48 hours after an explosive radiological dispersal device has been detonated.
Traditionally, the concept of As Low As Reasonably Achievable (ALARA) has been applied to the workplace and to protect the public. The goals are to minimize small incremental exposures on a daily basis or per specific task, and on a yearly basis, thereby to keep the total annual dose equivalent as far below regulatory limits as practical. In an extreme emergency caused by radiological or nuclear terrorism, or a large scale radiological accident, it is proposed that the same principles can be applied to protect First Responders against potentially large exposures.
VThis 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. Health Phys. 105(1):65Y73; 2013
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