RISK-RDD, a Radiological Incident Risk Management Tool

B.M. Biwer; D.J. LePoire; M.A. Lazaro; T. Allison; S. Kamboj; and S.Y. Chen (Argonne National Laboratory)

The release of a radiological dispersal device (RDD) in an urban area is an example of a radiological incident that may lead to a wide range of human health and economic impacts. The Department of Homeland Security has proposed an "optimization" process to decide on intervention and cleanup strategies. The RISK-RDD computer program offers a means to address such issues by assessing these impacts to better prepare local, state, and federal agencies in their efforts to deploy countermeasures. It is designed to cover all three phases (early, intermediate, and late) of any incident scenario. RISK-RDD is based on a GIS platform that allows for visualization of the affected area with interactive input and output. Scenarios ranging from an unshielded source to an aerosolized vapor cloud can be assessed. The program incorporates a series of current peer-reviewed models to estimate downwind air dispersion. These include the ERAD explosive release model, a simple urban canopy puff/plume model, and advanced deposition routines from AERMOD. In some scenarios considered thus far, significant health effects are not estimated beyond a few hundred meters for most of the commonly available radioactive sources. However, a significant external radiation threat to nearby individuals and emergency responders would exist from an unshielded source or scattered radioactive RDD fragments in the vicinity of a detonation. RISK-RDD incorporates semi-empirical algorithms to determine dose rates from such scenarios and also includes methods developed for the U.S. Nuclear Regulatory Commission to evaluate acute exposures. Economic impacts from an RDD event also occur when land and property require decontamination or disposal. By using the IMPLAN model and user-input dose limits, RISK-RDD estimates the direct and indirect business disruption impacts from the loss of use of land and property, including lost sales, income, and jobs, and the impacts associated with cleanup and reconstruction. The submitted manuscript has been created by the University of Chicago as Operator of Argonne National Laboratory ("Argonne") under Contract No. W-31-109-ENG-38 with the U.S. Department of Energy. The U.S. Government retains for itself, and others acting on its behalf, a paid-up, nonexclusive, irrevocable worldwide license in said article to reproduce, prepare derivative works, distribute copies to the public, and perform publicly and display publicly, by or on behalf of the Government.

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