SUMMARY

Following a nuclear detonation, large populations are likely to become externally contaminated due to direct deposition or resuspension of nuclear fallout. Those who are potentially contaminated will be screened to determine the necessity of immediate decontamination. Several organizations have suggested generic screening criteria for external contamination; however, inconsistencies remain among these values. Following a nuclear detonation, the isotopic composition of fallout changes rapidly further complicating the issue. Atmospheric dispersion causes additional variation in the isotopic composition with respect to distance due to varying particle sizes. This work used the Defense Land Fallout Interpretive Code (DELFIC) and the Oak Ridge Isotope Generation Fallout Analysis Tool (ORIGEN-FAT) to develop a temporally and spatially dependent database of isotopic compositions of fallout. Monte Carlo simulations were used to calculate air kerma rate, meter response, and dose rate coefficients for each radionuclide contained in the database. Along with the isotopic composition database, these coefficients were used to evaluate suggested screening criteria in terms of dose to the contaminated individual and the associated dose to public health staff. Screening criteria which result in doses below the ICRP Publication 103 public skin and effective dose limits to those given instructions for self-decontamination were identified. Higher screening criteria which will prevent deterministic effects were identified for use in the event of limited resources. Regarding public health staff, the study found that exposures exceeding the ICRP Publication 103 occupational dose limits was unlikely regardless of time or distance from ground zero.