SUMMARY

Following a nuclear detonation, large populations may become externally contaminated due to nuclear fallout. Those who are potentially contaminated will be monitored to determine the necessity of immediate decontamination. Several organizations have suggested generic screening criteria for external contamination; however, inconsistencies remain among these values. Following an improvised nuclear device (IND) detonation, the radionuclide composition of fallout changes rapidly as the large number of short-lived isotopes decay, further complicating the issue. Atmospheric dispersion causes additional variation in the radionuclide composition with respect to distance due to varying particle sizes.
This work will use the Defense Land Fallout Interpretive Code (DELFIC) and the Oak Ridge Isotope Generation (ORIGEN) Fallout Analysis Tool to determine the radionuclide composition at various distances from ground zero. Monte Carlo modeling and PiMAL phantoms will then be used to identify the top dose producing radionuclides as a function of both distance from ground zero and time since detonation and to determine the associated external radiation levels due to external contamination. These data will be analyzed in the context of suggested screening criteria for external contamination during early phase population monitoring. Additionally, published resuspension rates will be used to assess the risks posed by inhalation of resuspended contamination to first-aid, shelter, and reception center personnel.