Post-blast radiological dispersal device source term estimation

Research is underway to develop instruments and methods to determine the activity of radionuclides present in the fallout debris from the detonation of a radiological dispersal device (RDD). Handheld instruments, including commonly used health physics survey instruments, have been incorporated into a portable telemetry kit containing a global positioning system receiver, WiFi and radio communications, and a small microcomputer to facilitate data processing, logging, and transmission. An operator carries the system and walks through the RDD post-blast environment, real-time radiological data is logged, stored locally, and transmitted to a base station outside of the RDD hot zone. A map of the distributed radiological dispersal is generated, subdividing the world into 1-m
²
squares. Separate measurements of ground activity taken at a finite number of discrete locations is used to cross-correlate the survey data, transforming the health physics data (e.g., mrem hr
^-1
) to surface activity (Bq m
^-2
). The map data, smoothed using standard Kriging approaches, is then analyzed by summing each discrete square area, producing an estimate for the total dispersed ground activity. The instrumentation and method have been field tested multiple times at Idaho National Laboratory during field exercises using short-lived radionuclides detonated in small-scale experiments.