Modeling of RDD Scenarios and Derivation of Operational Guidelines for RDD Consequence Management

C. Yu1; J. Cheng1; S. Kamboj1; A. Miron1; D. LePoire1; B. Biwer1; C.R. Yuen1; T. Klett1; S.Y. Chen1; S. Domotor2; and A. Wallo III2 (1Argonne National Laboratory; 2Department of Energy)

Operational guidelines for a radiological dispersal device (RDD) incident were developed by the Consequence Management Subgroup's Operational Guidelines Task Group (OGT). The methodology and parameters were developed through a consensus-based process that involved all OGT members. Operational Guidelines (Groups A-F), corresponding to specific Protective Action Guides, were derived for 11 potential RDD radionuclides: Am-241, Cf-252, Cm-244, Co-60, Cs-137, Ir-192, Po-210, Pu-238, Pu-239, Ra-226, and Sr-90. For the early response phase (Group A), a straightforward concentration method or an exposure-to-dose conversion-factor method was used to derive stay time tables. For the late response phase (Group F), the probabilistic RESRAD and RESRAD-BUILD codes were used to derive property release criteria. The methodology developed for the intermediate response phase (Groups B-E) assumes that an outdoor RDD event would contaminate streets, soils, and building surfaces with radioactive materials. Building interiors would also be contaminated as a result of air exchange and human traffic. The methodology can also be modified for an indoor RDD event by considering different source partitioning factors. The model considers decay, weathering, a time-dependent resuspension factor, and concentration ratios (partitioning factors) between contaminated areas. A set of exposure pathways was considered in the model: external exposure from contaminants on streets, soils, and buildings; inhalation of dust particles; external exposure from submersion; ingestion of dust particles and plant foods; and indoor radon inhalation. Operational guidelines for each group were derived by using a systematic approach in which (1) applicable scenarios for each group were defined, (2) appropriate receptors for each scenario were identified, and (3) the receptor doses from applicable exposure pathways were estimated. Tools are being developed for incident-specific evaluation of RDD operational guidelines.

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