Computer Modeling of Radiation Portal Monitors for Homeland Security Applications

Radiation Portal Monitors (RPMs) are currently being used at our nation’s borders to detect potential nuclear threats. At the Pacific Northwest National Laboratory (PNNL), realistic computer models of RPMs are being developed to simulate the screening of vehicles and cargo. Detailed models of the detection equipment, vehicles, cargo containers, cargos, and radioactive sources are being used to determine the optimal configuration of detectors. These models can also be used to support work to optimize alarming algorithms so that they maximize sensitivity for items of interest while minimizing nuisance alarms triggered by legitimate radioactive material in the commerce stream. Proposed next-generation equipment is also being modeled to quantify performance and capability improvements to detect potential nuclear threats. A discussion of the methodology used to perform computer modeling for RPMs will be provided. In addition, the efforts to validate models used to perform these scenario analyses will be described. Finally, areas where improved modeling capability is needed will be discussed as a guide to future development efforts.