Computer-assisted Protective Action Recommendation System

Once released into the atmosphere, hazardous materials can affect people well beyond the immediate area of the emergency. The path, timing, and impacts from a release must be rapidly predicted, but the predictions are complicated by complex and changeable weather patterns.

AlphaTRAC has developed and implemented a modeling system to predict the path and impacts of hazardous materials emergencies. Called the Computer-assisted Protective Action Recommendation System (CAPARS), the system addresses the need for fast and accurate plume predictions.

CAPARS provides a variety of plume, weather, hazard, and related products with the accuracy and speed needed for response to hazardous materials emergencies and includes a number of key features.

Automated Communications • • •
CAPARS includes a dedicated subsystem to manage the communication channels which acquire automated meteorological data from around a region. The communication subsystem also manages the streams of internet-based outputs.

Geographic Information System Integration • • •
CAPARS integrates atmospheric dispersion modeling with Geographic Information System (GIS) technology to produce high-resolution graphics showing predicted plume travel. The GIS system provides geographical data, provides the user with an interactive interface, maintains source information databases, and produces high-resolution graphical and tabular outputs.

The Terrain-responsive Atmospheric Code • • •
Because the atmosphere is complex and changeable, great care and considerable sophistication must be used in atmospheric dispersion modeling if plume path and impact predictions are to be useful during emergency response. Recognizing the difficulty of this requirement, the U.S. Department of Energy developed a specialized atmospheric dispersion model for use in areas—such as mountainous terrain—with especially complex airflow patterns.

Called the Terrain-responsive Atmospheric Code (TRAC), the computer program has been used for emergency plume predictions in the mountainous terrain of the Appalachian and Rocky Mountains. TRAC is based on a "puff" approach to modeling, in which small clouds of hazardous materials are tracked through the atmosphere. The model predicts plume transport by developing wind flow patterns in three dimensions, then transporting the puffs along independent, curved trajectories. The TRAC model's reliability has been demonstrated in countless tests and trials, as well as in actual hazardous material events.

Customized Output • • •
One of the primary objectives of CAPARS is to clearly and rapidly communicate protective action recommendations and other support information to emergency managers and responders. Example products include maps of protective action zones, plume path maps, and contour maps of air concentration, radiation dose, and ground deposition.