ABSTRACT
ABSTRACT: 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.
ABSTRACT
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.
